Report
ULTRASTRUCTURAL FINDINGS IN INCONTINENTIA PIGMENTI R. CAPUTO, F. CIANOTTI AND M. INNOCENTl
The characteristic lesions are cutaneous ones, in most cases developing according to a 3-stage pattern. The first, or vesiculobullous stage, takes place during the first month of life. Lesions are arranged along peculiar lines (the so-called nevoid lines). Histologically, they are intraepidermal vesicles filled with eosinophils, often surrounded by dyskeratotic cells, either isolated or in small clusters. The second, or papuloverrucous stage, lasts a few months and is represented by hyperkeratotic, acanthotic and dyskeratotic lesions evolving to form remarkable amorphous keratin clusters among the multiple granular layers. Clusters of intra- and extracellular pigment granules are found in the dermal papillae. This pigment migrates into melanophages in the superficial dermis during the third, or pigmentary stage, where it remains for 2 years or more. During the pigmentary stage melanin may be scanty in the cells of the basal layer, while some cells of this layer and of the lower spinous layer show vacuolization and degeneration. The ultrastructural findings in incontinentia pigmenti have so far been studied by Cebhart (1970),'* Wong et al. (1971),i6 Schmidt et al. (1972)i2 and Schamburg-Lever and Lever (1973)."
from the Clinic of Dermatology, University ol Milan, Milan, Italy
ABSTRACT: From their uitrastructural study of incontlnenti pigmenti, the authors confirm that in this condition there is no pigmentary anomaly, but that pigmentation is the last step oi a still unknown process. At birth those who are affected display an intracellular edema which leads to the formation ot a vesicobutta. tn att 3 stages, the epidermis shows dyskeratotic ce//s and a transient pigmentary discharge.
Incontinentia pigmenti is characterized by a peculiarly arranged temporary pigmentation of the skin, often associated with malformations of the eyes, the teeth and the central nervous system. It occurs almost exclusively in females, although only rarely is there a familial tendency. The condition may be congenital or appear in early infancy. Its pathogenesis is still unknown, but it is thought to be an inflammatory process, possibly of viral origin. The severity of ma/formations is directly related to the time of onset in the fetus. Another suggestion would make this a dominant autosomal genetic anomaly, either lethal in males or related to the sex gene in the X chromosome. Address for reprints: R. Caputo, Clinica Dermatologua, Universita di Milano, Via Pace 9, Italia. 46
No. 1
INCONTINENTIA PICMENTI • Caputo, et al.
47
Studying a case at the vesiculobullous stage, Gebharf* observed that the vesicle formed near dyskeratotic cells and started with intracellular edema. In a patient in the pigmented papule stage, Wong et al.''' observed the presence in the upper epidermis of atypical melanocytes containing giant vacuoles and myelin figures. The meianocytes in the basal layer appeared to be normal. Gaps were found in the basal lamina. Two hypotheses were put forward by these authors: (1) the dyskeratotic cells of the upper epidermis might be atypical melanocytes and (2) the pigment discharge from the epidermis to the dermis would take place through gaps in the basal lamina, allowing the escape of extracellular melanosomes or of the dendritic processes of melanocytes. In a patient in the pigmentary stage, Schmidt et al.'^ found numerous melanosomes within the cells of the basal layer, vacuolization of both basal cells and melanocytes, and a large number of melanophages in the dermis, the basal lamina being unmodified. These authors did not formulate any hypothesis on the mode of pigment discharge. The most recent work was the one by Schamburg-Lever and Lever," who examined all the stages of incontinentia pigmenti in 3 patients, and came to the conclusion that all 3 stages constantly were characterized by dyskeratosis, phagocytosis of dyskeratotic cells and of melanosomes by macrophages, and the presence of melanophages in the upper dermis.
phagocytized melanosomes. The basal lamina was normal and showed gaps only where macrophages crossed it. On the basis of ultrastructural findings, the 3 stages of this condition appeared to be related to each other. The pigmentary incontinence possibly can be accounted for by the presence of dyskeratotic cells in the epidermis leading to a migration of macrophages into the epidermis, where they phagocytize dyskeratotic cells and melanosomes and subsequently return to the dermis. In 3 patients we studied all 3 stages of the disease for the purpose of contributing to a better understanding of its fine structure.
In addition to these common features, an intraepidermal blister was a finding of the first stage, ln the second and third stages Schwann cells were found frequently in the dermis close to the dermoepidermal junction with extensions above the basal lamina, where they
Vesiculobullous lesions
Materials and Methods
The ultrastructural examination was performed on 3 patients with incontinentia pigmenti who exhibited all 3 stages. Lesions of the vesiculobullous stage were examined in 2, while those of the verrucous stage were studied in all 3 and those of the pigmentary stage only in one. The samples were fixed in 1% osmium tetroxide in Millonig buffer^ for 4 hours at 4° C and were subsequently dehydrated in acetone and embedded in Vestopal, according to the method described by Caputo and Lombardi.^ The sections, cut on an LKB Ultratome microtome, were stained with uranyl acetate and lead citrate and examined with an EM 200 Philips electron microscope. Results
In the epidermis adjacent to a vesicobulla, large numbers of keratinocytes of the spinous layer and a few keratinocytes of the granular layer exhibit features indicative of edema in the perinuclear area (Fig. 1). This area of edema may be
48
INTERNATIONAL JOURNAL OF DERMATOLOCY Jan./Feb. 1975
Vol. 14
Fig. 1—Top, vesiculobullous stage. Circumscribed perinuclear edema of a cell in the spinous layer. (N, nucleus; x31,000) Fig. 2—Bottom, vesiculobullous stage. Edema affecting the whole perinuclear area of a cell of the granular layer. Mitochondria are swollen while tonofilaments have a whorl-like arrangement. (N, nucleus; x14,000)
limited in extent and the general ultrastructure of the cell may be only slightly modified; in other cases it is associated with mitochondrial swelling and a whorllike arrangement of tonofilaments around the edematous area (Fig. 2). ' The nuclear membrane seems to remain normal, even when the cell is highly modified. Quite a few dyskeratotic cells
are also observed, with large bundles of tonofilaments arranged around their nuclei. Bullous lesions can be rather small (Fig. 3), containing clusters of fibrin and cellular debris, or large and filled with leukocytes (especially eosinophils) (Fig. 4). The roof is formed by generally well preserved cells of the spinous and granular layers, while the
No. 1
Fig. 3—^Top, vesiculobullous stage. A small blister containing no eosinophils. These can however be observed in adjacent intercellular spaces. (B, blister; x9,000) Fig. 4— Bottom, vesiculobullous stage. Content of a large blister, where cellular debris and eosinophils can be observed. (E, eosinophil; x5,000)
INCONTINENTIA PICMENTI • Caputo, et al.
49
/ ^ ^ i, '^ ,V "^^ {,-•«• \ ^
floor is made up of cells of the basal layer. The basal lamina is normal. Pigment is normally distributed throughout the epidermis and is absent from the dermis. Papulo-verrucous lesions In this type of lesion the dermis, which was slightly edematous, contains nu-
merous very large cells, possibly histiocytes, with clusters of mature melanin granules in the cytoplasm. Some of these are surrounded by a membrane. Numerous mast cells are also present in the dermis at this stage (Fig. 5). Schwann cells are often observed. The epidermis is rich in melanocytes, with prominent dendrites and premel-
INTERNATIONAL JOURNAL OF DERMATOLOCY Jan./Feb. 1975
'• ,' •- • ^liU'
A^ ' f^'ueJ-® / ! ! Vtki.'^Oi \ !-'•
^ ~
anosomes, melanosomes and other normal-appearing cytoplasmic organelles. The basal lamina is unbroken and frequently adjoins melanocyte dendrites (Fig. 6). Basal layer keratinocytes appear essentially normal, but the spinous layer is acanthotic and numerous melanocyte
Vol.
""'S- ^ —
Top
papuloverrucou: stage. Numerou
melanophages anw some mast celi. are present in iht dermis. (Me, mel^ anophage; Mg^ mast cell; x12,500J Fig. 6 — Bottom papulove rrucou» stage. Melanocytt, pseudopod locaten close to the intaci basal lamina. (BI, basal lamina, x3S' 000) '
dendrites are seen in the enlarged intercellular spaces. In addition, isolated dyskeratotic cells are present (Fig. 7), some of which show swelling of mitochondria and phagosomes. Other cells' are made up of round clusters of tonofilaments, nuclear residues, granules of melanin and other cytoplasmic or-
No. 1
INCONTINENTIA PICMENTI • Caputo, et al.
51
Fig. 7 — papuloverrucous stage. Typical dyskeratotic cell. (N, nucleus; T, tonofilaments; Xi 9,800) In the insert: a dyskeratotic cell reduced to a cluster of tonofilaments and cellular debris.
ganelles; they have no desmosomes (Fig. 7, insert). Intracytoplasmic desmosomes within dyskeratotic cells were found only in one patient of the 3 examined. The granular layer (Fig. 8) is formed by
several layers of cells containing numerous polymorphous granules of keratohyalin. Keratinosomes are numerous, both within the cytoplasm and in the intercellular spaces (Fig 8, insert). Melanosome complexes are quite abundant
52
INTERNATIONAL JOURNAL OF DERMATOLOGY Jan./Feb. 1975
- i Fig. 8—Papuloverrucous stage. Gell of the granular layer, rich in melanosome complexes. (N, nucleus; K, keratohyalin granule; x31,000) In the insert; keratinosomes in the intercellular space, x67,000.
and distributed around the nuclei of the granular cells (Fig. 8). The horny layer is remarkably thickened. Pigmentary lesions . In these lesions, the epidermal keratinocytes are almost normal apart from
some swelling of mitochondria in cells of the basal layer and the presence of a few dyskeratotic cells in the spinous layer. Generally in keratinocytes, the melanosome complexes are less numerous than in the papuloverrucous
No. 1
INGONTINENTIA PIGMENTI • Caputo, et al.
53
Fig. 9—Pigmentary stage. Superficial dermis where clusters of both intra- and extracellular (arrows) melanosomes can be seen. (E, epidermis; D, dermis; BL, basal )amina; Me, melanophage; xl 9,800)
lesions, and the melanocytes have no apparent abnormalities. ln the dermis (Fig. 9) there are many melanin-rich macrophages, especially in the form of compound melanosomes limited by a membrane, and containing groups of 20 or more granules. Some of
these melanophages have an edematous cytoplasm, swollen mitochondria and a broken cell membrane. For this reason, melanin granules are often found lying free in the dermis, whereas Schwann cells that contain no melanosomes are only rarely found.
54
INTERNATIONAL JOURNAL OF DERMATOLOGY Jan./Feb. 1975
Conclusions We know from the data reported in the literature as well as from the results of our research that the constant and typical finding in all 3 stages is the presence of dyskeratotic cells. These cells have no desmosomes and are similar to those observed in Darier's disease,3' 7, ''- '0 in Hailey-Hailey disease''- '^ and in Bowen's disease.•'• " According to Schamburg-Lever and Lever," these cells do not mature and may be phagocytized by macrophages. A few dyskeratotic cells, generally surrounded by cells having a normal structure, are found in both vesiculobullous and pigmentary stages. They are abundant in lesions of the papuloverrucous stage. The role played by these cells has not yet been clarified. The mode of formation of the vesicobulla in the first stage and the process of pigmentary discharge were the 2 main problems investigated by electron microscopy. According to the data of Gebharf* and our own, the process of formation of the vesicobulla would start with an intracytoplasmic edema of limited extent, which would subsequently spread to the whole perinuclear area and be associated to mitochondrial swelling. The breaking of the cellular membrane of some adjacent cells would lead to the formation of cavities initially containing only clusters of fibrin and cellular debris. Eosinophils were observed only in the largest bullous lesions. According to Gebhart,'* dyskeratotic cells scattered around the blister would lead to the migration of polymorphonuclear eosinophils. In all the stages, Schamburg-Lever and Lever'i constantly found melanophages in the superficial dermis, while we observed them only in the verrucous and pigmentary stages. Furthermore, in the verrucous stage we also found a remark-
Vol. 14
able increase of compound melanosomes in keratocytes, even in the granular layer. Wong et al."" found atypical vacuolated melanocytes in the superficial epidermis. On the basis of these findings, 2 hypotheses have been made in connection with pigmentary discharge. According to Wong et al."' and Gurrier,'' the pigmentary discharge would take place through gaps in the basal lamina which would allow the escape of both extracellular melanosomes and melanocyte pseudopods from the epidermis to the dermis. According to Schamburg-Lever and Lever," the pigmentary incontinence would be the consequence of a phagocytic phenomenon. The dyskeratotic cells of the epidermis would induce a migration of macrophages to the epidermis, where they would phagocytize dyskeratotic cells and melanosomes, subsequently returning to the dermis. Schwann cells, close to the basal lamina and often containing melanosome complexes, would also be involved in this process. They are observed both in the verrucous and in the pigmentary stages. Unfortunately, the very intense investigations we carried out in this connection did not support any of these two hypotheses, since we observed neither gaps in the basal lamina nor dermal macrophages containing residues of dyskeratotic cells, nor Schwann cells containing melanosomes. In conclusion, the ultrastructural investigations carried out up to now have confirmed that in incontinentia pigmenti there is no pigmentary anomaly, but rather that pigmentation is merely the last step of a still unknown process. This process often begins during intrauterine life and becomes evident at birth, with an intracellular edema which leads to the formation of a vesicobulla. In all the stages, this process is characterized by
No. 1
INGONTINENTIA PIGMENTI • Caputo, et al.
the presence in the epidermis of dyskeratotic cells and ends by a transient pigmentary discharge. References 1. Bloch, B., Eigentumliche bisher nicht beschriebene Pigmentaffection (Incontinentia Pigmenti). Schweiz. Med. Wochenschr. 56; 404, 1926. 2. Gaputo, R., Lombardi, L., Ouadri ultrastrutturali dell'epidermide umana normale. Atti Ace. Med. Lombarda 18:72, 1963. 3. Gaulfield, J. B., Wilgram, G. F., An electron microscope study of dyskeratosis and acantholoysis in Darier's disease. J. Invest. Dermatol. 41:57, 1963. 4. Gebhart, W., Elektronenmikroskopische Befunde cfer Epidermis in visculos-entzundlichen FriJnstadium bei Incontinentia Pigmenti. Microscopia Gutis Electronica Documenta IV Simposii Dermatologorum Brno VI, 1970 219-226. 5. Gottlieb, S., Lutzer M., Hailey-Hailey disease: An electron microscope study. J. Invest. Dermalol. 54:368, 1970. 6. Gurrier, G., A suggested mode of pigment transfer into the dermis. Acta Derm. Venereol. 53:173, 1973. 7. Mann P., Haye K. R., An electron microscope study of the acantholytic and dyskeratotic processes in Darier's disease. Br. j . Dermatol. 82:561, 1970.
55
8. Millonig, G., Further observations on a buffer for osmium solution. Proc. 5th Intern. Gongr. of Electron Microscopy. Philadelphia, New York, Academic Press, 1962. 9. Olson, R., Nordquist, R., Everett, M. A., Dyskeratosis in Bowen's disease. Br. ]. Dermatol. 81:676, 1969. 10. Pierard, J., Kint, A., Die Darfersche Krankheit. Arch. Klin. Exp. Dermatol. 231:382, 1968. 11. Schamburg-Lever, G., Lever, W. F., Electron microscopy of incontinentia pigmenti. J. Invest. Dermatol. 61:151, 1973. 12. Schmidt, H., Huidberg, Hansen, J., Ghristensen, H. E., Incontinentia pigmenti with associated lesions in two generations. Acta Derm. Venereol. 52:281, 1972. 13. Seiji, M., Mizuno, - F., Electron microscopic study of Bowen's disease. Arch. Dermatol. 99:3, 1969. 14. Sulzberger, M. B., Uber eine bisher nicht beschriebene congenitale pigmentanomalie (Incontinentia Pigmenti). Arch. Derm. Syph. 154:19, 1928. 15. Wilgram, G. F., Gaulfield, j . B., Lewer, W. F., An electron microscopic study of acantholysis and dyskeratosis in Hailey and Hailey disease. J. Invest. Dermatol. 39:373, 1962. 16. Wong, D. K., Gurrier, G. J., MacMillan, D. G., Vickers, R. V., An electron microscopical study of Block-Sulzberger syndrome (incontinentia pigmenti). Acta Derm. Venereol. 51:161, 1971.
"Specialization" as applied to medicine comprehends a large and varied! group of activities and interests. The development of medicine in theory and, practice since the sixteenth century has been characterized by an increas-j ing expansion and complexity, ln the course of this evolution a growing] number of foci of interest appear. Certain of these foci of interest become organized and delimited as separate fields of practice, and are known as' specialties. From this point of view a medical specialty may be regarded as a field of medical activity organized about a focus of interest. Such a foci of interest within the field of medicine are subject to the operation of two processes, segmentation and accretion, which lead to the appearance of new specialties. As a field of practice develops around a focus of interest it may divide giving rise to two or more new fields (segmentation). On the other hand, the cultivation of an area between two fields may lead to their merger and the appearance of a new specialty (accretion).—Pp. 199-200 from Rosen, G.: "Whither Specialization," in Bell, W. j.: Medicine and Society, American Philosophical Society Library, Philadelphia, 1971.
ULTRASTRUCTURAL FINDINGS IN INCONTINENTIA PIGMENTI R. CAPUTO, F. CIANOTTI AND M. INNOCENTl
The characteristic lesions are cutaneous ones, in most cases developing according to a 3-stage pattern. The first, or vesiculobullous stage, takes place during the first month of life. Lesions are arranged along peculiar lines (the so-called nevoid lines). Histologically, they are intraepidermal vesicles filled with eosinophils, often surrounded by dyskeratotic cells, either isolated or in small clusters. The second, or papuloverrucous stage, lasts a few months and is represented by hyperkeratotic, acanthotic and dyskeratotic lesions evolving to form remarkable amorphous keratin clusters among the multiple granular layers. Clusters of intra- and extracellular pigment granules are found in the dermal papillae. This pigment migrates into melanophages in the superficial dermis during the third, or pigmentary stage, where it remains for 2 years or more. During the pigmentary stage melanin may be scanty in the cells of the basal layer, while some cells of this layer and of the lower spinous layer show vacuolization and degeneration. The ultrastructural findings in incontinentia pigmenti have so far been studied by Cebhart (1970),'* Wong et al. (1971),i6 Schmidt et al. (1972)i2 and Schamburg-Lever and Lever (1973)."
from the Clinic of Dermatology, University ol Milan, Milan, Italy
ABSTRACT: From their uitrastructural study of incontlnenti pigmenti, the authors confirm that in this condition there is no pigmentary anomaly, but that pigmentation is the last step oi a still unknown process. At birth those who are affected display an intracellular edema which leads to the formation ot a vesicobutta. tn att 3 stages, the epidermis shows dyskeratotic ce//s and a transient pigmentary discharge.
Incontinentia pigmenti is characterized by a peculiarly arranged temporary pigmentation of the skin, often associated with malformations of the eyes, the teeth and the central nervous system. It occurs almost exclusively in females, although only rarely is there a familial tendency. The condition may be congenital or appear in early infancy. Its pathogenesis is still unknown, but it is thought to be an inflammatory process, possibly of viral origin. The severity of ma/formations is directly related to the time of onset in the fetus. Another suggestion would make this a dominant autosomal genetic anomaly, either lethal in males or related to the sex gene in the X chromosome. Address for reprints: R. Caputo, Clinica Dermatologua, Universita di Milano, Via Pace 9, Italia. 46
No. 1
INCONTINENTIA PICMENTI • Caputo, et al.
47
Studying a case at the vesiculobullous stage, Gebharf* observed that the vesicle formed near dyskeratotic cells and started with intracellular edema. In a patient in the pigmented papule stage, Wong et al.''' observed the presence in the upper epidermis of atypical melanocytes containing giant vacuoles and myelin figures. The meianocytes in the basal layer appeared to be normal. Gaps were found in the basal lamina. Two hypotheses were put forward by these authors: (1) the dyskeratotic cells of the upper epidermis might be atypical melanocytes and (2) the pigment discharge from the epidermis to the dermis would take place through gaps in the basal lamina, allowing the escape of extracellular melanosomes or of the dendritic processes of melanocytes. In a patient in the pigmentary stage, Schmidt et al.'^ found numerous melanosomes within the cells of the basal layer, vacuolization of both basal cells and melanocytes, and a large number of melanophages in the dermis, the basal lamina being unmodified. These authors did not formulate any hypothesis on the mode of pigment discharge. The most recent work was the one by Schamburg-Lever and Lever," who examined all the stages of incontinentia pigmenti in 3 patients, and came to the conclusion that all 3 stages constantly were characterized by dyskeratosis, phagocytosis of dyskeratotic cells and of melanosomes by macrophages, and the presence of melanophages in the upper dermis.
phagocytized melanosomes. The basal lamina was normal and showed gaps only where macrophages crossed it. On the basis of ultrastructural findings, the 3 stages of this condition appeared to be related to each other. The pigmentary incontinence possibly can be accounted for by the presence of dyskeratotic cells in the epidermis leading to a migration of macrophages into the epidermis, where they phagocytize dyskeratotic cells and melanosomes and subsequently return to the dermis. In 3 patients we studied all 3 stages of the disease for the purpose of contributing to a better understanding of its fine structure.
In addition to these common features, an intraepidermal blister was a finding of the first stage, ln the second and third stages Schwann cells were found frequently in the dermis close to the dermoepidermal junction with extensions above the basal lamina, where they
Vesiculobullous lesions
Materials and Methods
The ultrastructural examination was performed on 3 patients with incontinentia pigmenti who exhibited all 3 stages. Lesions of the vesiculobullous stage were examined in 2, while those of the verrucous stage were studied in all 3 and those of the pigmentary stage only in one. The samples were fixed in 1% osmium tetroxide in Millonig buffer^ for 4 hours at 4° C and were subsequently dehydrated in acetone and embedded in Vestopal, according to the method described by Caputo and Lombardi.^ The sections, cut on an LKB Ultratome microtome, were stained with uranyl acetate and lead citrate and examined with an EM 200 Philips electron microscope. Results
In the epidermis adjacent to a vesicobulla, large numbers of keratinocytes of the spinous layer and a few keratinocytes of the granular layer exhibit features indicative of edema in the perinuclear area (Fig. 1). This area of edema may be
48
INTERNATIONAL JOURNAL OF DERMATOLOCY Jan./Feb. 1975
Vol. 14
Fig. 1—Top, vesiculobullous stage. Circumscribed perinuclear edema of a cell in the spinous layer. (N, nucleus; x31,000) Fig. 2—Bottom, vesiculobullous stage. Edema affecting the whole perinuclear area of a cell of the granular layer. Mitochondria are swollen while tonofilaments have a whorl-like arrangement. (N, nucleus; x14,000)
limited in extent and the general ultrastructure of the cell may be only slightly modified; in other cases it is associated with mitochondrial swelling and a whorllike arrangement of tonofilaments around the edematous area (Fig. 2). ' The nuclear membrane seems to remain normal, even when the cell is highly modified. Quite a few dyskeratotic cells
are also observed, with large bundles of tonofilaments arranged around their nuclei. Bullous lesions can be rather small (Fig. 3), containing clusters of fibrin and cellular debris, or large and filled with leukocytes (especially eosinophils) (Fig. 4). The roof is formed by generally well preserved cells of the spinous and granular layers, while the
No. 1
Fig. 3—^Top, vesiculobullous stage. A small blister containing no eosinophils. These can however be observed in adjacent intercellular spaces. (B, blister; x9,000) Fig. 4— Bottom, vesiculobullous stage. Content of a large blister, where cellular debris and eosinophils can be observed. (E, eosinophil; x5,000)
INCONTINENTIA PICMENTI • Caputo, et al.
49
/ ^ ^ i, '^ ,V "^^ {,-•«• \ ^
floor is made up of cells of the basal layer. The basal lamina is normal. Pigment is normally distributed throughout the epidermis and is absent from the dermis. Papulo-verrucous lesions In this type of lesion the dermis, which was slightly edematous, contains nu-
merous very large cells, possibly histiocytes, with clusters of mature melanin granules in the cytoplasm. Some of these are surrounded by a membrane. Numerous mast cells are also present in the dermis at this stage (Fig. 5). Schwann cells are often observed. The epidermis is rich in melanocytes, with prominent dendrites and premel-
INTERNATIONAL JOURNAL OF DERMATOLOCY Jan./Feb. 1975
'• ,' •- • ^liU'
A^ ' f^'ueJ-® / ! ! Vtki.'^Oi \ !-'•
^ ~
anosomes, melanosomes and other normal-appearing cytoplasmic organelles. The basal lamina is unbroken and frequently adjoins melanocyte dendrites (Fig. 6). Basal layer keratinocytes appear essentially normal, but the spinous layer is acanthotic and numerous melanocyte
Vol.
""'S- ^ —
Top
papuloverrucou: stage. Numerou
melanophages anw some mast celi. are present in iht dermis. (Me, mel^ anophage; Mg^ mast cell; x12,500J Fig. 6 — Bottom papulove rrucou» stage. Melanocytt, pseudopod locaten close to the intaci basal lamina. (BI, basal lamina, x3S' 000) '
dendrites are seen in the enlarged intercellular spaces. In addition, isolated dyskeratotic cells are present (Fig. 7), some of which show swelling of mitochondria and phagosomes. Other cells' are made up of round clusters of tonofilaments, nuclear residues, granules of melanin and other cytoplasmic or-
No. 1
INCONTINENTIA PICMENTI • Caputo, et al.
51
Fig. 7 — papuloverrucous stage. Typical dyskeratotic cell. (N, nucleus; T, tonofilaments; Xi 9,800) In the insert: a dyskeratotic cell reduced to a cluster of tonofilaments and cellular debris.
ganelles; they have no desmosomes (Fig. 7, insert). Intracytoplasmic desmosomes within dyskeratotic cells were found only in one patient of the 3 examined. The granular layer (Fig. 8) is formed by
several layers of cells containing numerous polymorphous granules of keratohyalin. Keratinosomes are numerous, both within the cytoplasm and in the intercellular spaces (Fig 8, insert). Melanosome complexes are quite abundant
52
INTERNATIONAL JOURNAL OF DERMATOLOGY Jan./Feb. 1975
- i Fig. 8—Papuloverrucous stage. Gell of the granular layer, rich in melanosome complexes. (N, nucleus; K, keratohyalin granule; x31,000) In the insert; keratinosomes in the intercellular space, x67,000.
and distributed around the nuclei of the granular cells (Fig. 8). The horny layer is remarkably thickened. Pigmentary lesions . In these lesions, the epidermal keratinocytes are almost normal apart from
some swelling of mitochondria in cells of the basal layer and the presence of a few dyskeratotic cells in the spinous layer. Generally in keratinocytes, the melanosome complexes are less numerous than in the papuloverrucous
No. 1
INGONTINENTIA PIGMENTI • Caputo, et al.
53
Fig. 9—Pigmentary stage. Superficial dermis where clusters of both intra- and extracellular (arrows) melanosomes can be seen. (E, epidermis; D, dermis; BL, basal )amina; Me, melanophage; xl 9,800)
lesions, and the melanocytes have no apparent abnormalities. ln the dermis (Fig. 9) there are many melanin-rich macrophages, especially in the form of compound melanosomes limited by a membrane, and containing groups of 20 or more granules. Some of
these melanophages have an edematous cytoplasm, swollen mitochondria and a broken cell membrane. For this reason, melanin granules are often found lying free in the dermis, whereas Schwann cells that contain no melanosomes are only rarely found.
54
INTERNATIONAL JOURNAL OF DERMATOLOGY Jan./Feb. 1975
Conclusions We know from the data reported in the literature as well as from the results of our research that the constant and typical finding in all 3 stages is the presence of dyskeratotic cells. These cells have no desmosomes and are similar to those observed in Darier's disease,3' 7, ''- '0 in Hailey-Hailey disease''- '^ and in Bowen's disease.•'• " According to Schamburg-Lever and Lever," these cells do not mature and may be phagocytized by macrophages. A few dyskeratotic cells, generally surrounded by cells having a normal structure, are found in both vesiculobullous and pigmentary stages. They are abundant in lesions of the papuloverrucous stage. The role played by these cells has not yet been clarified. The mode of formation of the vesicobulla in the first stage and the process of pigmentary discharge were the 2 main problems investigated by electron microscopy. According to the data of Gebharf* and our own, the process of formation of the vesicobulla would start with an intracytoplasmic edema of limited extent, which would subsequently spread to the whole perinuclear area and be associated to mitochondrial swelling. The breaking of the cellular membrane of some adjacent cells would lead to the formation of cavities initially containing only clusters of fibrin and cellular debris. Eosinophils were observed only in the largest bullous lesions. According to Gebhart,'* dyskeratotic cells scattered around the blister would lead to the migration of polymorphonuclear eosinophils. In all the stages, Schamburg-Lever and Lever'i constantly found melanophages in the superficial dermis, while we observed them only in the verrucous and pigmentary stages. Furthermore, in the verrucous stage we also found a remark-
Vol. 14
able increase of compound melanosomes in keratocytes, even in the granular layer. Wong et al."" found atypical vacuolated melanocytes in the superficial epidermis. On the basis of these findings, 2 hypotheses have been made in connection with pigmentary discharge. According to Wong et al."' and Gurrier,'' the pigmentary discharge would take place through gaps in the basal lamina which would allow the escape of both extracellular melanosomes and melanocyte pseudopods from the epidermis to the dermis. According to Schamburg-Lever and Lever," the pigmentary incontinence would be the consequence of a phagocytic phenomenon. The dyskeratotic cells of the epidermis would induce a migration of macrophages to the epidermis, where they would phagocytize dyskeratotic cells and melanosomes, subsequently returning to the dermis. Schwann cells, close to the basal lamina and often containing melanosome complexes, would also be involved in this process. They are observed both in the verrucous and in the pigmentary stages. Unfortunately, the very intense investigations we carried out in this connection did not support any of these two hypotheses, since we observed neither gaps in the basal lamina nor dermal macrophages containing residues of dyskeratotic cells, nor Schwann cells containing melanosomes. In conclusion, the ultrastructural investigations carried out up to now have confirmed that in incontinentia pigmenti there is no pigmentary anomaly, but rather that pigmentation is merely the last step of a still unknown process. This process often begins during intrauterine life and becomes evident at birth, with an intracellular edema which leads to the formation of a vesicobulla. In all the stages, this process is characterized by
No. 1
INGONTINENTIA PIGMENTI • Caputo, et al.
the presence in the epidermis of dyskeratotic cells and ends by a transient pigmentary discharge. References 1. Bloch, B., Eigentumliche bisher nicht beschriebene Pigmentaffection (Incontinentia Pigmenti). Schweiz. Med. Wochenschr. 56; 404, 1926. 2. Gaputo, R., Lombardi, L., Ouadri ultrastrutturali dell'epidermide umana normale. Atti Ace. Med. Lombarda 18:72, 1963. 3. Gaulfield, J. B., Wilgram, G. F., An electron microscope study of dyskeratosis and acantholoysis in Darier's disease. J. Invest. Dermatol. 41:57, 1963. 4. Gebhart, W., Elektronenmikroskopische Befunde cfer Epidermis in visculos-entzundlichen FriJnstadium bei Incontinentia Pigmenti. Microscopia Gutis Electronica Documenta IV Simposii Dermatologorum Brno VI, 1970 219-226. 5. Gottlieb, S., Lutzer M., Hailey-Hailey disease: An electron microscope study. J. Invest. Dermalol. 54:368, 1970. 6. Gurrier, G., A suggested mode of pigment transfer into the dermis. Acta Derm. Venereol. 53:173, 1973. 7. Mann P., Haye K. R., An electron microscope study of the acantholytic and dyskeratotic processes in Darier's disease. Br. j . Dermatol. 82:561, 1970.
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8. Millonig, G., Further observations on a buffer for osmium solution. Proc. 5th Intern. Gongr. of Electron Microscopy. Philadelphia, New York, Academic Press, 1962. 9. Olson, R., Nordquist, R., Everett, M. A., Dyskeratosis in Bowen's disease. Br. ]. Dermatol. 81:676, 1969. 10. Pierard, J., Kint, A., Die Darfersche Krankheit. Arch. Klin. Exp. Dermatol. 231:382, 1968. 11. Schamburg-Lever, G., Lever, W. F., Electron microscopy of incontinentia pigmenti. J. Invest. Dermatol. 61:151, 1973. 12. Schmidt, H., Huidberg, Hansen, J., Ghristensen, H. E., Incontinentia pigmenti with associated lesions in two generations. Acta Derm. Venereol. 52:281, 1972. 13. Seiji, M., Mizuno, - F., Electron microscopic study of Bowen's disease. Arch. Dermatol. 99:3, 1969. 14. Sulzberger, M. B., Uber eine bisher nicht beschriebene congenitale pigmentanomalie (Incontinentia Pigmenti). Arch. Derm. Syph. 154:19, 1928. 15. Wilgram, G. F., Gaulfield, j . B., Lewer, W. F., An electron microscopic study of acantholysis and dyskeratosis in Hailey and Hailey disease. J. Invest. Dermatol. 39:373, 1962. 16. Wong, D. K., Gurrier, G. J., MacMillan, D. G., Vickers, R. V., An electron microscopical study of Block-Sulzberger syndrome (incontinentia pigmenti). Acta Derm. Venereol. 51:161, 1971.
"Specialization" as applied to medicine comprehends a large and varied! group of activities and interests. The development of medicine in theory and, practice since the sixteenth century has been characterized by an increas-j ing expansion and complexity, ln the course of this evolution a growing] number of foci of interest appear. Certain of these foci of interest become organized and delimited as separate fields of practice, and are known as' specialties. From this point of view a medical specialty may be regarded as a field of medical activity organized about a focus of interest. Such a foci of interest within the field of medicine are subject to the operation of two processes, segmentation and accretion, which lead to the appearance of new specialties. As a field of practice develops around a focus of interest it may divide giving rise to two or more new fields (segmentation). On the other hand, the cultivation of an area between two fields may lead to their merger and the appearance of a new specialty (accretion).—Pp. 199-200 from Rosen, G.: "Whither Specialization," in Bell, W. j.: Medicine and Society, American Philosophical Society Library, Philadelphia, 1971.
