Volume 24 Number 4 April 1991
Multiple BCCs and HLA frequencies in southern Australia
the closer the patients live to the equator. The relative risk of patients in the study of Myskowski et al. from New York was 4.08; for Cerimele's Sardinians it was 3.02; and for our patients from Melbourne it was 2.10. It appears that environmental factors override heredity and this association may not be present in white persons who have lived most of their lives in the tropics. REFERENCES
1. Giles G, Marks R, Foley P. Incidence of non-melanocyfic skin cancer treated in Australia. Br Med J 1988;296:13-7. 2. Robinson J. Risk of developing another basal cell carcinoma: a 5-year prospective study. Cancer 1987;60:118-20. 3. GeUin G, Kopf A, Garfunkle L. Basal cell epithelioma: a controlled study of associated factors. Arch Dermatol 1965;91:35-45. 4. Silverstone H, Searle JHA. The epidemiology of skin cancer in Queensland: the influence of phenotype and environment. Br J Cancer 1970;24:235-52.
5. Vitaliano PP, Urbach F. The relative importance of risk factors in non-melanoma carcinoma. Arch Dermatol 1980; 116:454-6. 6. Hogan D J, To T, Gran L, et al. Risk factors for basal cell carcinoma. Int J Dermatol 1989;28:591-4. 7. Gupta AK, Cardella C J, Haberrnan H. Cutaneous malignant neoplasms in patients with renal transplants. Arch Dermatol 1986;122:1288-93. 8. Myskowski PL, Pollacks MS, Schorr E, et al. Human leukocyte antigen associations in basal cell carcinoma. J AM ACAD DERMATOL1985;12:997-1000. 9. Cerimele D, Contu I, Careassi C. HLA and multiple skin cancers. Dermatologica 1988;176:176-81. 10. Giraldo G, Degos L, Beth E, et al. H L A antigens in 16 families with xeroderma pigmentosum. Tissue Antigens 1977;9:167-70. 11. Holge SE, Degos L, Walford RL. Four chromosomal instability syndromes: Bloom's syndrome, Fanconi's anaemia, Werner's syndrome, and xeroderma pigrnentosum. In: Teraski PI, ed. Histocompatibility testing 1980. L ~ Angeles: UCLA Tissue Typing Laboratory, 1980: 730-1.
Ill
I
Atypical polypoid dermatofibroma: Report of two cases Lluis Puig, MD, Jordi Esquius, MD, Maria Teresa Fernfindez-Figueras, MD, Abelardo Moreno, MD, and Jos6 M. de Moragas, MD Barcelona, Spain Two cases of a hitherto undesedbed special variant of dermatofibroma are reported. A man and a woman, aged 57 and 52 years, respectively, had slowly growing cutaneous tumors on the lower extremities. The tumors were exophytic and polypoid, 10 and 6 cm in maximal diameters, respectively; they were covered by rough nonulcerated skin and were joined by a short pedicle to an indurated base. Histologic examination showed some features of an otherwise conventionaldermatofibroma, whereas the polypoid component was hypercellular and showed striking atypia and scattered mitotic figures. After 32 and 28 months' follow-up, the lesions did not recur after surgical excision. We suggest the term atypicalpolypoid derma-
tofibroma to summarize the special clinicopathologic features of these tumors. (J AM ACAD D~.RMATOL 1991;24:561-5.) Dermatofibromas are usually readily recognized both clinically and microscopically although they may be variable in size and shape (depressed, fiat, nodular, or polypoid) as well as in their microscopic appearance. Depending on which cell population From the Departments of Dermatologyand Pathology,Hospital de la Santa Creu i Sant Pau, Universidad Autrnoma de Barcelona. Accepted for publication Oct. 23, 1990. Reprint requests:ProfessorJos6 M. de Moragas, MD, Chairman, Dept. of Dermatology,Hospital de la Santa Creu i Sant Pau, Avda. San Antonio M. Claret 167, 08025 Barcelona,Spain.
predominates in a particular lesion, different histologic variants such as the fibrocollagenous, histiocytic, vascular (sclerosing hemangioma), storiform, aneurysmal ("angiomatoid"), and transitional types have been described. 1 Rarely, some dermatofibromas show cytologic atypia, which is often focal but can be prominent and histologically worrisome despite the benign nature of the lesion. These lesions have been called atypicaI, pseudosarcomatous, or monster cell dermatofibroma.2, 3 We report two cases of an unusual and special variant of dermatofibroma characterized by
561
Jotlrnal American
562
Puig et al.
of the
Academy
of
Dermatology
~,5~iii:i i:!84 ~
! ~ ~ 9 9149 :~
Fig. 2. Case 2. Close-up view of lesion. Hemorrhagic nodule is apparent on outer aspect of cup-shaped polypoid component of lesion. Fig. 1. Case 1. Exophytic component of tumor is elevated by tweezers, showing its polypoid character.
distinctive clinicopathologic features t h a t we have attempted to summarize under the descriptive term atypical polypoid dermatofibroma ( A P D F ) . CASE REPORTS
Case 1. A 57-year-old white man had a slowly growing, flesh-colored, fingerlike, pediculated tumor, 10 • • 1.5 cm, on the posterior surface of the left leg (Fig. 1). A similar lesion in the same location had been excised 17 years earlier. The surgical specimen from the original procedure was available for review and showed identical histopathologic features. The tumor was excised and the wound grafted in December 1987. There has been no further evidence of recurrence after 32 months of followup. Case 2. A 5 2-year-old white woman had recent bleeding in a pedunculated, brown to flesh-colored exophytic tumor, 6 cm in maximal diameter, on an indurated area of skin on the posterior surface of her left thigh. There was a soft hemorrhagic nodule, 7 mm in diameter, on the outer surface of the polyp (Fig. 2). According to the patient, the lesion had originally been a long-standing asymptomatic pigmented "mole" that started to grow slowly after a trauma 14 years before and became pedunculated. The
lesion was excised with no evidence of recurrence, 28 months later. I-Iistopathologie features. The histopathologic findings were similar in both cases. The base and the exophytic portion of the tumors disclosed different features. At the implantation site, interlacing bundles of collagen and spindle cells, frequently arranged in a storiform pattern, merged imperceptibly with the neighboring dermal tissue similar to a classic dermatofibroma. In the exophytic component of the tumor cellular proliferation was denser, with spindle cells closely packed in storiform and whorllike fashion (Fig. 3). Some nuclei were pleomorphic with dense and coarse chromatin pattern and prominent nucleoli (Fig. 4); there were scattered mitoses, more abundant in the most superficial areas (two to three per 10 high-power fields) and occasionally atypical (Fig. 5). There were focal areas of hemorrhage with inflammatory changes, xanthoma formation, and hemosiderin deposition. The overlying epidermis, occasionally separated from the dermal tumor by a grenz zone, showed irregular hyperplasia with follicular induction and focal ulceration. Additional sections were stained by means of an ABC immunoperoxidase method with the following commercial monoclonal antibodies: anti--S-100 protein (Dako, 1:1600), anti--al-antitrypsin (Immustain, 1:5), antidesmin (Dako, 1:5), and antivimentin (Dako, 1:50). Both tumors gave a diffuse, cytoplasmic, strong, and homoge-
Volume 24 Number 4 April 1991
Atypical polypoid dermatofibroma
563
Fig. 3. Histopathologic appearance of exophytic component of tumor, showing dense cellular proliferation, with spindle ceils closely packed in storiform and whorl-like fashion. (Hematoxylin-eosin stain; X 100.)
Fig. 4. Nuclear pleomorphism, with dense and coarse chromatin pattern and prominent nucleoli in a significant proportion of the cell population. (Hematoxylin-eosin stain; • neous stain for vimentin. S- 100 protein and a :antitrypsin were also expressed in some tumor cells. Labeling for desmin was uniformly negative. DISCUSSION Our two cases may represent a distinctive clinicopathologic variant of dermatofibroma that, to our knowledge, has not been described. Histologically, these tumors are a mixture of the so-called "fibrocollagenous" and "storiform" variants of classical dermatofibroma but in a peculiar combination.
At the implantation site, the pattern of the tumor is fibrocollagenous, with spindle cells interspersed in a dense collagenous stroma. By contrast, the exophytic portion is characterized by a dense aggregation of fibrohistiocytic cells grouped mainly in a storiform pattern with intermingled lipid-containing histiocytes, inflammatory cells, hemosiderin deposits, and capillaries. There are scattered atypical tumor ceils with large nuclei and a reticulated chromatin pattern. What appears ~to be a striking and perhaps a worrisome histologic characteristic of
564
Puig et al.
Journal of the American Academy of Dermatology
Fig. 5. Abundant mitoses, frequently atypical, were seen in exophytic portion of tumor. (Hematoxylin-eosin stain; • A P D F is the presence of mitoses (two to three per 10 high-power fields), especially in the superficial and mid portions of the tumor. Vimentin expression in tumor cells provides evidence for the mesenchymal fibroblastic nature of these neoplasms. Negative staining for desmin ruled out a myofibroblastic differentiation, o~l-Antitrypsin and S-100 protein, although originally described as specific markers for histiocytic and melanocytic/ neural cells, respectively, may be expressed in a wide range of different neoplasms and are of little value in the consideration of tumor histogenesis. 4 Factor XIIIa is specifically present in the normal fixed dermal connective tissue cells and in 30% to 70% of the constituent cells in conventional histiocytomas, 5 as well as in other reactive and. neoplastic "fibrohistiocytic" lesions. 6 Thus the term dermal dendrocytoma has been recently introduced for tumors that possibly originate from dermal dendrocytes 5 and that probably would have been previousIy referred to as dermatofibromas or fibrohistiocytomas. 7 A P D F m a y clinically simulate pleomorphic fibroma of the skin, a newly recognized entity reported by Kamino et al., 8 that is the atypical counterpart of soft fibromas of skin. These tumors on the extremities or trunk of middle-aged patients were described as slow-growing, polypoid or domeshaped, covered by intact smooth-surfaced skin, and measuring from 0,4 to 1.6 cm in greatest dimension. Thus pleomorphic fibroma of the skin and A P D F
may have some overlapping clinical features although the latter are larger. Furthermore, on microscopic examination, pleomorphic fibromas of the skin have sparse, occasionally atypical cellularity with predominance of thick collagen bundles in a haphazard array. 8 Histologically, and especially when a small biopsy specimen is studied, A P D F may resemble an atypical cutaneous fibrous histiocytoma. This tumor has been reviewed by several authors under the heading "atypical (pseudosarcomatous) cutaneous histiocytoma" or "dermatofibroma with monster cells." This entity is not well clinically characterized, but tumors are characteristically found on the trunk and limbs of middle-aged women. Microscopically, there are scattered and irregular atypical and pleomorphic cells in the setting of a conventional dermatofibroma. Recently, Leyva and Santa Cruz 9 have recognized two histologic types of atypical cutaneous fibrous histiocytoma. The fibroblastic type is characterized by large atypical cells with pleomorphic, hyperchromatic, and often multinucleated nuclei, with prominent nucleoli. These cells are scattered among interlacing bundles of fibroblastic cells and collagen in an otherwise conventional fibrocollagenous dermatofibroma. These changes are focal and can be found in approximately 20% of tumor cells. The histiocytic type is characterized by poorly circumscribed nodules that tend to be more cellular than in the spindle cell type. The tumors are
Volume 24 Number 4 April 1991
composed of lipid-containing histiocytes both single and multinucleated (Touton cells), fibroblasts, and numerous small capillaries. Considerable nuclear atypia can be seen in more than 50% of the foamy histiocytes and multinucleated cells. The absence of atypical mitoses is a histologic hallmark of atypical cutaneous fibrous histiocytoma that has been reported to be helpful in the differential diagnosis of atypical fibroxanthoma, malignant fibrous histiocytoma of the skin, 1~ 11 and, for that matter, APDF. Furthermore, polypoid lesions have not yet been reported as a clinical presentation of atypical cutaneous fibrous histiocytoma. More commonly atypical fibroxanthomas arise on sun-damaged areas in elderly persons. In the less common form the lesions occur on the limbs and trunk of younger persons. Atypical fibroxanthomas are usually less than 2 cm in diameter. HistologicaUy, they are characterized by a proliferation of spindle-shaped or rounded bizarre cells with multinucleation, pleomorphism, and numerous typical and atypical mitoses. Cellular density varies from area to area but the tumor is usually closely attached to an atrophic epidermal surface without delimitation by a grenz zone. On the contrary, APDFs seem to have no predilection for sun-exposed areas, are characteristically large and polypoid, and resemble a conventional dermatofibroma with a grenz zone, epidermal hyperplasia, and follicular induction. These features are enough to distinguish easily atypical fibroxanthoma from APDF. 12 Despite these differences, all these tumors can be considered as belonging to a spectrum of cutaneous and soft tissue fibrohistiocytic neoplasms. 2, 3 Aneurysmal ("angiomatoid") fibrous histiocytoma of the skin constitutes a variant of dermatofibroma with special clinical presentation and pathologic features. Aneurysmal fibrous histiocytoma presents as blue, black, or dark nodules, almost always on the extremities and sometimes associated with pain and rapid growth. HistologicaUy, aneurysmal fibrous histiocytomas are highly cellular with
Atypical polypoid derrnatofibroma 565 fibroblasts and histiocytic ceils arranged in a storiform pattern with scant collagen; foamy histiocytes, scattered inflammatory cells, and hemosiderin deposits may also be prominent. These are found in APDF but what is characteristic of aneurysmal fibrous histiocytoma is the presence of blood-filled tissue spaces of variable size and shape, devoid of endothelium, and lined or surrounded by fibroblasts, histiocytes, and giant cells. Although such microscopic features may be poorly or not at all represented in small specimens, the clinical picture described seems to be sufficient to differentiate these tumors.13 REFERENCES
1. Vilanova JR, Flint A. The morphological variations of fibrous histiocytomas.,J Cutan Pathoi 1974;1:l 55-64. 2. Fukamizu H, O k u - T , Inoue K, et al. Atypical ("pseudosarcomatous') cutaneous histiocytoma. J Cutan Pathol 1983;10:327-33. 3. Tamada S, Ackerman AB. Dermatofibroma with monster cells. Am J Dermatopathol 1987;9:380-7. 4. Bennington JL. Immunomicroscopy: a diagnostic tool for the surgical pathologist. In: Major problems in pathology; vol 19. Philadelphia: WB Saunders, 1986. 5. Cerio R, Spaull J, Jones EW. Histiocytoma cutis: a tumor of dermal dendrocytes (dermal dendrocytoma). Br J Dermatol 1989;120:197-206. 6. Reid M, Gray C, Fear J, et al. lmmunohistochemical demonstration of factors XIIIa and Xllls in reactive and neoplastic fibroblastic and fibrohistiocytic lesions. Histopathology 1986;10:1171-8. 7. Gray MH, Smoller BR, McNutt NS, et al. Giant dermal dendrocytoma of the face: a distinct clinicopathologic entity. Arch Derrnatol 1990;126:689-90. 8. Kamino H, Lee JY-Y, Berke A. Pleomorphic fibroma of the skin: a benign neoplasm with cytologic atypia. Am J Surg Pathol 1989;13:107-13. 9. Leyva WH, Santa Cruz DJ. Atypical cutaneous fibrous histiocytoma. Am J Dermatopathol 1986;8:467-7 I. 10. Ackerman AB, Ragaz A. The lives of lesions. New York: Masson, 1984:45. 11. Ackerman AB, Troy JL, Rosen LB, et al. Differential diagnosis in dermatopathology II. Philadelphia: Lea & Febiger, 1988:74-7. 12. Fretzin DF, Helwig EB. Atypical fibroxanthoma of the skin: a clinicopathologic study of 140 cases. Cancer 1973; 31:1541-52. 13. Santa Cruz D J, Kyriakos M. Aneurysmal (angiomatoid) fibrous histiocytoma of the skin. Cancer 1981;47:2053-61.
Multiple BCCs and HLA frequencies in southern Australia
the closer the patients live to the equator. The relative risk of patients in the study of Myskowski et al. from New York was 4.08; for Cerimele's Sardinians it was 3.02; and for our patients from Melbourne it was 2.10. It appears that environmental factors override heredity and this association may not be present in white persons who have lived most of their lives in the tropics. REFERENCES
1. Giles G, Marks R, Foley P. Incidence of non-melanocyfic skin cancer treated in Australia. Br Med J 1988;296:13-7. 2. Robinson J. Risk of developing another basal cell carcinoma: a 5-year prospective study. Cancer 1987;60:118-20. 3. GeUin G, Kopf A, Garfunkle L. Basal cell epithelioma: a controlled study of associated factors. Arch Dermatol 1965;91:35-45. 4. Silverstone H, Searle JHA. The epidemiology of skin cancer in Queensland: the influence of phenotype and environment. Br J Cancer 1970;24:235-52.
5. Vitaliano PP, Urbach F. The relative importance of risk factors in non-melanoma carcinoma. Arch Dermatol 1980; 116:454-6. 6. Hogan D J, To T, Gran L, et al. Risk factors for basal cell carcinoma. Int J Dermatol 1989;28:591-4. 7. Gupta AK, Cardella C J, Haberrnan H. Cutaneous malignant neoplasms in patients with renal transplants. Arch Dermatol 1986;122:1288-93. 8. Myskowski PL, Pollacks MS, Schorr E, et al. Human leukocyte antigen associations in basal cell carcinoma. J AM ACAD DERMATOL1985;12:997-1000. 9. Cerimele D, Contu I, Careassi C. HLA and multiple skin cancers. Dermatologica 1988;176:176-81. 10. Giraldo G, Degos L, Beth E, et al. H L A antigens in 16 families with xeroderma pigmentosum. Tissue Antigens 1977;9:167-70. 11. Holge SE, Degos L, Walford RL. Four chromosomal instability syndromes: Bloom's syndrome, Fanconi's anaemia, Werner's syndrome, and xeroderma pigrnentosum. In: Teraski PI, ed. Histocompatibility testing 1980. L ~ Angeles: UCLA Tissue Typing Laboratory, 1980: 730-1.
Ill
I
Atypical polypoid dermatofibroma: Report of two cases Lluis Puig, MD, Jordi Esquius, MD, Maria Teresa Fernfindez-Figueras, MD, Abelardo Moreno, MD, and Jos6 M. de Moragas, MD Barcelona, Spain Two cases of a hitherto undesedbed special variant of dermatofibroma are reported. A man and a woman, aged 57 and 52 years, respectively, had slowly growing cutaneous tumors on the lower extremities. The tumors were exophytic and polypoid, 10 and 6 cm in maximal diameters, respectively; they were covered by rough nonulcerated skin and were joined by a short pedicle to an indurated base. Histologic examination showed some features of an otherwise conventionaldermatofibroma, whereas the polypoid component was hypercellular and showed striking atypia and scattered mitotic figures. After 32 and 28 months' follow-up, the lesions did not recur after surgical excision. We suggest the term atypicalpolypoid derma-
tofibroma to summarize the special clinicopathologic features of these tumors. (J AM ACAD D~.RMATOL 1991;24:561-5.) Dermatofibromas are usually readily recognized both clinically and microscopically although they may be variable in size and shape (depressed, fiat, nodular, or polypoid) as well as in their microscopic appearance. Depending on which cell population From the Departments of Dermatologyand Pathology,Hospital de la Santa Creu i Sant Pau, Universidad Autrnoma de Barcelona. Accepted for publication Oct. 23, 1990. Reprint requests:ProfessorJos6 M. de Moragas, MD, Chairman, Dept. of Dermatology,Hospital de la Santa Creu i Sant Pau, Avda. San Antonio M. Claret 167, 08025 Barcelona,Spain.
predominates in a particular lesion, different histologic variants such as the fibrocollagenous, histiocytic, vascular (sclerosing hemangioma), storiform, aneurysmal ("angiomatoid"), and transitional types have been described. 1 Rarely, some dermatofibromas show cytologic atypia, which is often focal but can be prominent and histologically worrisome despite the benign nature of the lesion. These lesions have been called atypicaI, pseudosarcomatous, or monster cell dermatofibroma.2, 3 We report two cases of an unusual and special variant of dermatofibroma characterized by
561
Jotlrnal American
562
Puig et al.
of the
Academy
of
Dermatology
~,5~iii:i i:!84 ~
! ~ ~ 9 9149 :~
Fig. 2. Case 2. Close-up view of lesion. Hemorrhagic nodule is apparent on outer aspect of cup-shaped polypoid component of lesion. Fig. 1. Case 1. Exophytic component of tumor is elevated by tweezers, showing its polypoid character.
distinctive clinicopathologic features t h a t we have attempted to summarize under the descriptive term atypical polypoid dermatofibroma ( A P D F ) . CASE REPORTS
Case 1. A 57-year-old white man had a slowly growing, flesh-colored, fingerlike, pediculated tumor, 10 • • 1.5 cm, on the posterior surface of the left leg (Fig. 1). A similar lesion in the same location had been excised 17 years earlier. The surgical specimen from the original procedure was available for review and showed identical histopathologic features. The tumor was excised and the wound grafted in December 1987. There has been no further evidence of recurrence after 32 months of followup. Case 2. A 5 2-year-old white woman had recent bleeding in a pedunculated, brown to flesh-colored exophytic tumor, 6 cm in maximal diameter, on an indurated area of skin on the posterior surface of her left thigh. There was a soft hemorrhagic nodule, 7 mm in diameter, on the outer surface of the polyp (Fig. 2). According to the patient, the lesion had originally been a long-standing asymptomatic pigmented "mole" that started to grow slowly after a trauma 14 years before and became pedunculated. The
lesion was excised with no evidence of recurrence, 28 months later. I-Iistopathologie features. The histopathologic findings were similar in both cases. The base and the exophytic portion of the tumors disclosed different features. At the implantation site, interlacing bundles of collagen and spindle cells, frequently arranged in a storiform pattern, merged imperceptibly with the neighboring dermal tissue similar to a classic dermatofibroma. In the exophytic component of the tumor cellular proliferation was denser, with spindle cells closely packed in storiform and whorllike fashion (Fig. 3). Some nuclei were pleomorphic with dense and coarse chromatin pattern and prominent nucleoli (Fig. 4); there were scattered mitoses, more abundant in the most superficial areas (two to three per 10 high-power fields) and occasionally atypical (Fig. 5). There were focal areas of hemorrhage with inflammatory changes, xanthoma formation, and hemosiderin deposition. The overlying epidermis, occasionally separated from the dermal tumor by a grenz zone, showed irregular hyperplasia with follicular induction and focal ulceration. Additional sections were stained by means of an ABC immunoperoxidase method with the following commercial monoclonal antibodies: anti--S-100 protein (Dako, 1:1600), anti--al-antitrypsin (Immustain, 1:5), antidesmin (Dako, 1:5), and antivimentin (Dako, 1:50). Both tumors gave a diffuse, cytoplasmic, strong, and homoge-
Volume 24 Number 4 April 1991
Atypical polypoid dermatofibroma
563
Fig. 3. Histopathologic appearance of exophytic component of tumor, showing dense cellular proliferation, with spindle ceils closely packed in storiform and whorl-like fashion. (Hematoxylin-eosin stain; X 100.)
Fig. 4. Nuclear pleomorphism, with dense and coarse chromatin pattern and prominent nucleoli in a significant proportion of the cell population. (Hematoxylin-eosin stain; • neous stain for vimentin. S- 100 protein and a :antitrypsin were also expressed in some tumor cells. Labeling for desmin was uniformly negative. DISCUSSION Our two cases may represent a distinctive clinicopathologic variant of dermatofibroma that, to our knowledge, has not been described. Histologically, these tumors are a mixture of the so-called "fibrocollagenous" and "storiform" variants of classical dermatofibroma but in a peculiar combination.
At the implantation site, the pattern of the tumor is fibrocollagenous, with spindle cells interspersed in a dense collagenous stroma. By contrast, the exophytic portion is characterized by a dense aggregation of fibrohistiocytic cells grouped mainly in a storiform pattern with intermingled lipid-containing histiocytes, inflammatory cells, hemosiderin deposits, and capillaries. There are scattered atypical tumor ceils with large nuclei and a reticulated chromatin pattern. What appears ~to be a striking and perhaps a worrisome histologic characteristic of
564
Puig et al.
Journal of the American Academy of Dermatology
Fig. 5. Abundant mitoses, frequently atypical, were seen in exophytic portion of tumor. (Hematoxylin-eosin stain; • A P D F is the presence of mitoses (two to three per 10 high-power fields), especially in the superficial and mid portions of the tumor. Vimentin expression in tumor cells provides evidence for the mesenchymal fibroblastic nature of these neoplasms. Negative staining for desmin ruled out a myofibroblastic differentiation, o~l-Antitrypsin and S-100 protein, although originally described as specific markers for histiocytic and melanocytic/ neural cells, respectively, may be expressed in a wide range of different neoplasms and are of little value in the consideration of tumor histogenesis. 4 Factor XIIIa is specifically present in the normal fixed dermal connective tissue cells and in 30% to 70% of the constituent cells in conventional histiocytomas, 5 as well as in other reactive and. neoplastic "fibrohistiocytic" lesions. 6 Thus the term dermal dendrocytoma has been recently introduced for tumors that possibly originate from dermal dendrocytes 5 and that probably would have been previousIy referred to as dermatofibromas or fibrohistiocytomas. 7 A P D F m a y clinically simulate pleomorphic fibroma of the skin, a newly recognized entity reported by Kamino et al., 8 that is the atypical counterpart of soft fibromas of skin. These tumors on the extremities or trunk of middle-aged patients were described as slow-growing, polypoid or domeshaped, covered by intact smooth-surfaced skin, and measuring from 0,4 to 1.6 cm in greatest dimension. Thus pleomorphic fibroma of the skin and A P D F
may have some overlapping clinical features although the latter are larger. Furthermore, on microscopic examination, pleomorphic fibromas of the skin have sparse, occasionally atypical cellularity with predominance of thick collagen bundles in a haphazard array. 8 Histologically, and especially when a small biopsy specimen is studied, A P D F may resemble an atypical cutaneous fibrous histiocytoma. This tumor has been reviewed by several authors under the heading "atypical (pseudosarcomatous) cutaneous histiocytoma" or "dermatofibroma with monster cells." This entity is not well clinically characterized, but tumors are characteristically found on the trunk and limbs of middle-aged women. Microscopically, there are scattered and irregular atypical and pleomorphic cells in the setting of a conventional dermatofibroma. Recently, Leyva and Santa Cruz 9 have recognized two histologic types of atypical cutaneous fibrous histiocytoma. The fibroblastic type is characterized by large atypical cells with pleomorphic, hyperchromatic, and often multinucleated nuclei, with prominent nucleoli. These cells are scattered among interlacing bundles of fibroblastic cells and collagen in an otherwise conventional fibrocollagenous dermatofibroma. These changes are focal and can be found in approximately 20% of tumor cells. The histiocytic type is characterized by poorly circumscribed nodules that tend to be more cellular than in the spindle cell type. The tumors are
Volume 24 Number 4 April 1991
composed of lipid-containing histiocytes both single and multinucleated (Touton cells), fibroblasts, and numerous small capillaries. Considerable nuclear atypia can be seen in more than 50% of the foamy histiocytes and multinucleated cells. The absence of atypical mitoses is a histologic hallmark of atypical cutaneous fibrous histiocytoma that has been reported to be helpful in the differential diagnosis of atypical fibroxanthoma, malignant fibrous histiocytoma of the skin, 1~ 11 and, for that matter, APDF. Furthermore, polypoid lesions have not yet been reported as a clinical presentation of atypical cutaneous fibrous histiocytoma. More commonly atypical fibroxanthomas arise on sun-damaged areas in elderly persons. In the less common form the lesions occur on the limbs and trunk of younger persons. Atypical fibroxanthomas are usually less than 2 cm in diameter. HistologicaUy, they are characterized by a proliferation of spindle-shaped or rounded bizarre cells with multinucleation, pleomorphism, and numerous typical and atypical mitoses. Cellular density varies from area to area but the tumor is usually closely attached to an atrophic epidermal surface without delimitation by a grenz zone. On the contrary, APDFs seem to have no predilection for sun-exposed areas, are characteristically large and polypoid, and resemble a conventional dermatofibroma with a grenz zone, epidermal hyperplasia, and follicular induction. These features are enough to distinguish easily atypical fibroxanthoma from APDF. 12 Despite these differences, all these tumors can be considered as belonging to a spectrum of cutaneous and soft tissue fibrohistiocytic neoplasms. 2, 3 Aneurysmal ("angiomatoid") fibrous histiocytoma of the skin constitutes a variant of dermatofibroma with special clinical presentation and pathologic features. Aneurysmal fibrous histiocytoma presents as blue, black, or dark nodules, almost always on the extremities and sometimes associated with pain and rapid growth. HistologicaUy, aneurysmal fibrous histiocytomas are highly cellular with
Atypical polypoid derrnatofibroma 565 fibroblasts and histiocytic ceils arranged in a storiform pattern with scant collagen; foamy histiocytes, scattered inflammatory cells, and hemosiderin deposits may also be prominent. These are found in APDF but what is characteristic of aneurysmal fibrous histiocytoma is the presence of blood-filled tissue spaces of variable size and shape, devoid of endothelium, and lined or surrounded by fibroblasts, histiocytes, and giant cells. Although such microscopic features may be poorly or not at all represented in small specimens, the clinical picture described seems to be sufficient to differentiate these tumors.13 REFERENCES
1. Vilanova JR, Flint A. The morphological variations of fibrous histiocytomas.,J Cutan Pathoi 1974;1:l 55-64. 2. Fukamizu H, O k u - T , Inoue K, et al. Atypical ("pseudosarcomatous') cutaneous histiocytoma. J Cutan Pathol 1983;10:327-33. 3. Tamada S, Ackerman AB. Dermatofibroma with monster cells. Am J Dermatopathol 1987;9:380-7. 4. Bennington JL. Immunomicroscopy: a diagnostic tool for the surgical pathologist. In: Major problems in pathology; vol 19. Philadelphia: WB Saunders, 1986. 5. Cerio R, Spaull J, Jones EW. Histiocytoma cutis: a tumor of dermal dendrocytes (dermal dendrocytoma). Br J Dermatol 1989;120:197-206. 6. Reid M, Gray C, Fear J, et al. lmmunohistochemical demonstration of factors XIIIa and Xllls in reactive and neoplastic fibroblastic and fibrohistiocytic lesions. Histopathology 1986;10:1171-8. 7. Gray MH, Smoller BR, McNutt NS, et al. Giant dermal dendrocytoma of the face: a distinct clinicopathologic entity. Arch Derrnatol 1990;126:689-90. 8. Kamino H, Lee JY-Y, Berke A. Pleomorphic fibroma of the skin: a benign neoplasm with cytologic atypia. Am J Surg Pathol 1989;13:107-13. 9. Leyva WH, Santa Cruz DJ. Atypical cutaneous fibrous histiocytoma. Am J Dermatopathol 1986;8:467-7 I. 10. Ackerman AB, Ragaz A. The lives of lesions. New York: Masson, 1984:45. 11. Ackerman AB, Troy JL, Rosen LB, et al. Differential diagnosis in dermatopathology II. Philadelphia: Lea & Febiger, 1988:74-7. 12. Fretzin DF, Helwig EB. Atypical fibroxanthoma of the skin: a clinicopathologic study of 140 cases. Cancer 1973; 31:1541-52. 13. Santa Cruz D J, Kyriakos M. Aneurysmal (angiomatoid) fibrous histiocytoma of the skin. Cancer 1981;47:2053-61.
