Path. Res. Pract. 188, 890-893 (1992)
Meningothelial Meningioma with "Amianthoid" Fibers Case Report with Ultrastructural Study R. Chuaqui, S. Gonzalez and G. Torrealba Departments of Pathology and Neurology and Neurosurgery, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
SUMMARY The case of a rneningothelial rneningi0111a with 'a111ianthoid' fibers in a 48-year-old W0111an is presented. By light microscopy the tumor showed the typical features of meningothelial meningioma emd rounded, deeply eosinophilic, and fibrillary areas, especially around and/or in the vicillity of blood vessels. These fibers are also ca lied 'amia11thoid' fibers. Ultrastructurally, these joci were made up of disorderly arral1ged and interlllaving mature collagen fibrils with a variable width between 40 and 190 nm. No evidence of intracellular collagen synthesis by the tumor cells was found. The presence of 'amianthoid' fibers does /lot seem to carry any prognostic signiflcance.
Introduction Meningioma is a frequent tumor constituing around 13% to 19% of primary neoplasms of the central nervous system 7 • Most ca ses are benign and of histologieal grade 1. The histopathologieal features of meningioma are well known and the diagnosis is usually made without diffieulties. Oeeasionally, eertain variants induee misdiagnosis because of subtle variations of their histologie aspeet. Moreover, some of these features may have an important morphogenetie andlor prognostie signifieanee. The main histologie al variants are: meningothelial, fibroblastie, transitional, psammomatous, angiomatous, papillomatous, hemangioperieytie, and anaplastie7 , and of these, the so-ealled hemangioperieytie variant of the angioblastie type, the papillomatous variant and the anaplastie one have an aggressive biologie behavior. The present report coneerns a very unusual variant of meningothelial meningioma showing the so-ealled 'amianthoid' fibers. Case Report A previously healths 48-year-old woman presented with ahistory of 1 week of sudden onset of headaehe, nausea, 0344-033 g/92/() 188-0890$3.5010
and vomiting. Clinieal examination revealed a left hemiparesis, bilateral papillary edema and meningeal signs. A brain CT sean showed a parasagital of 3.5 X 5 em in diameter in the right parietal area, 1 em near the median line, partially eollapsing the right lateral ventricle. At surgery, the duramater appeared protuberant and an extensive subdural hematoma partially overlying the tumor mass was evident. Postoperatively, partial remission of hemiparesis was observed and no evidenee of residual tumor has been recorded four months after the diagnosis.
Material and Methods Tumof sam pies wefl" fixed in 10% neutral formalin and routinely proeessed. Special stains included van Gieson's trichrome and phosphotungstic acid hematoxylin. From the formalin-fixed material 1 mm 3 sam pies were recuperated for clectron microscopy. They were postfixed in 050 4 and embedded in Epon 812. Toluidinc bluc-staincd semithin sections were obtained for orientation. Thin sections were stained wirh uranyl acetate and lead citrate and examined under a Zciss 109 electron nllcroscope. @
1992 by Gustav Fischer Verlag, Sttrttgart
Men ingothel ial Meningioma . 89 1
Results Light Microscopic Findings
The tumor was composed of l arge cells arranged in nests and small syncitialmasses. The cytoplasm was abundant, pale eosinophilic with pood y defined oudines. The nuclei were round to oval with small basophilic nucleoli and loose chromatin. Nuclear pseudoinclusions were easily found. Occasionally, larger and hyperchromatic nuclei were apparent, but neither necrosis nor atypical mitoses were found. The stro ma was scant. Rounded, deeply eosinophilic and fibrillary areas were conspicuous. They measured from 20 to 300 ~m in diameter disclosing a fibrillary arrangement and focally a starry appearance (Fig. 1 ). Some were located aro und sm all dilated blood vessels, whereas others were among tumor nests (Fig. 2). Van Gieson's trichrome s howed an intense red staining and a characteristic fibrillary appea rance. At the periphery of these foci, yellowish, amorphous material was also observed. Psammoma bodies and calcifications were not identified. Electron Microscopic F indings
Fig. 1. Meningotheli al m enill gioma w ith t ypieal stellate foei oE 'ami anthoid' fibers among tum o r cells. Van Gieson's trieh ro me, x 200. .
Tumor cells disclosed numero us interdigitating cytoplasmic projections and frequent desmosome-like and hemidesmosome-like intercellular junctions. The Golgi apparatus was well developed and dispersed cisternae o f ro ugh endoplasmic reticulum were also found. Mitochondria and lysosomes were s cant. The nuclei showed cytoplasmic invaginations and dense nucleoli. Intracytoplasmic intermediate filaments were occasionally observed. The fibrillary bodies were composed of disorderly arranged and interwaving mature collagen fibrils (Fig. 3). These showed the characteristic cross-striations of 65 nm periodicity of collagen fibrils. Fibrils' width varied from 40 to 190 nm, most of them b eing around 120 nm. Thinner
Fig.2. 'Amianthoid' fib er morphogenesis around blood vessels. (a) Condensation and deposition aro und a dilated blood vessel, (b) obliteration of vessel lumen, an d (c) final stage of full y develo ped body. Van Gieson 's t richrome, x 500.
Fig. 3. Electron microphotograph of 'amianthoid' fibers composed of mature collagen fibrils, disorderly arranged and of variable width. Uranyl acetate'and lead citrate, x 6,000.
Fig. 4. Thinner filaments intermingled with mature collagen fibrils at th e periphery of an 'amianthoid' fiber. Uranyl acetate and lead citrate, x 30,000.
Meningothelial Meningioma . 893
filaments around 10 nm in width were also found, especially at the periphery of the fibrillary body (Fig. 4). Discussion 'Amianthoid' fibers are composed of haphazardly arranged mature collagen fibrils, some of which are abnormally thicker. These fibers were first described in 'fibrillary transformation', 'fibrillary degeneration', or 'asbestoid degeneration' as an age-related regressive change of hyaline cartilage3 . It is frequent in degenerative diseases such as osteoarthritis and emphysema. The presence of 'amianthoid' fibers has been recorded in a variety of neoplasms, i.e. chondrosarcoma2 , synovia I sarcoma 6, malignant schwannoma6 , palisaded myofibroblastoma 8,9, neuroendocrine neoplasms 5 , and in a very unusual tumor called 'amianthioma' 1. In all these cases 'amianthoid' fibers have been described as mature collagen fibrils of varying width up to 1000 nm, randomly arranged, forming stellate bodies, occasionally perivascular, and intermingled with normal collagen fibrils. The so-called 'amianthioma' is a benign tumor of the skin and subcutaneous tissue, adjacent to the tibialis anterior musde, described in a 42-year-old woman and characterized by sheets of epithelioid cells in a wellvascularized stroma and with multiple 'amianthoid' bodies 1• Ultrastructurally, the tumor cells showed cytoplasmic projections, nudear indenqltions, with moderate amounts of organelles and occassional desmosome-like intercellular junctions. The 'amianthoid' fibers were identified as aggregates of dense collagen fibrils with characteristic 68 nm periodicity. They were described as thick fibers but the width was not recorded. Collagen fibrils depicted in Fig. 5 of Dr. Connolly's report measure up to 350 nm in width. The above-mentioned features of the 'amianthioma' are morphologically very similar to the tumor of the present case. The histogenesis of 'amianthoid' fibers is still unknown. Many authors believe that these fibers originate from a passive phenomenon of aggregation after age-related anoxic injury 3. It is not dear whether this apposition is due to depletion of glycosaminoglycanes and water of the matrix or whether the formation of hydrogen-cross linkes hold the component fibrils together 3 . However, this hypothesis does not satisfactorily explain the rather usual appearance of 'amianthoid' fibers around blood vessels in aseries of neoplasms 3 ,8. 'Amianthoid' fibers associated with synovial sarcoma and malignant schwannoma are dosely related to tumor cells showing ultrastructural
features suggestive of collagen synthesis. These signs include well developed Golgi apparatus, prominent rough endoplasmic reticulum with osmiophilic material in some dilated cisternae, dose apposition of tumor cell cytoplasm and the fibers, and even intracytoplasmic collagen fibrils 6• Thus, the possibility of active collagen synthesis by the tumor cells must also be seriously considered. In the present case no evidence of intracellular collagen synthesis was found. Harkin and Leonard4 reported a similar case in a 34-year-old woman with an intradural meningioma of the lumbar spinal cord. Histologically, this neoplasm also showed numerous eosinophilic and partially calcified nodules, which ultrastructurally corresponded to thick collagen fibrils similar to 'amianthoid' fibers. No evidence of fiber synthesis by the tumor cells was recorded. The tumor evolved without recurrence after two years of follow up. Morphologic evidence of malignancy was not found in our case and the patient is weil and alive without residual tumor 4 months after surgery. In our opinion, the presence of 'amianthoid' fibers does not carry any prognostic significance.
References 1 Connolly CE (1981) 'Crystalline' collagen production by an unusual benign soft tissue tumor ('amianthioma'). Histopathology 5: 11-20 2 Ghadially FN, Lalonde JMA, Yong NK (1980) Amianthoid fibers in a chondrosarcoma. J Pathol130: 147-151 3 Ghadially FN (1982) Ultrastructural Pathology of the Cell and Matrix. 2nd edition, Butterworths, London 4 Harkin JC, Leonard GL (1988) Abnormal amianthoid collagen fibers in meningioma. Acta Neuropatol 76: 638-639 5 Hull MT, Warfel KA. Ultrastructure of abnormal collagen in human tumors. Ultrastruct Pathol 10: 293-301 6 Orenstein JM (1983) Amianthoid fibers in a synovial sarcoma and a malignant schwannoma. Ultrastruct Pathol 4: 163-176 7 Russell OS, Rubinstein LJ (1989) Pathology of Tumours of the Nervous System. 5th edition, Williams & Wilkins, Baltimore 8 Suster S, Rosai (1989) Intranodal hemorrhagic spindle-cell tumor with 'amianthoid' fibers. Report of six cases of a distinctive mesenchymal neoplasm of the inguinal region that simulates Kaposi's sarcoma. Am J Surg Pathol13: 347-357 9 Weiss SM, Gnepp OR, Bratthauer GL (1':}89) Palisaded myofibroblastoma. A benign mesenchymal tumor of lymph node. Am J Surg Pathol13: 341-346
Received February 18, 1991 . Accepted in revised form August 29, 1991
Key words: Meningioma - Amianthoid fibers - Brain tumor - Collagen fibrils Sergio Gonzalez B., M.O. PhO., Oepartment of Pathology, Esc. de Medicina, Universidad Catolica de Chile, Casilla 114-0, Santiago, Chile
Meningothelial Meningioma with "Amianthoid" Fibers Case Report with Ultrastructural Study R. Chuaqui, S. Gonzalez and G. Torrealba Departments of Pathology and Neurology and Neurosurgery, School of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
SUMMARY The case of a rneningothelial rneningi0111a with 'a111ianthoid' fibers in a 48-year-old W0111an is presented. By light microscopy the tumor showed the typical features of meningothelial meningioma emd rounded, deeply eosinophilic, and fibrillary areas, especially around and/or in the vicillity of blood vessels. These fibers are also ca lied 'amia11thoid' fibers. Ultrastructurally, these joci were made up of disorderly arral1ged and interlllaving mature collagen fibrils with a variable width between 40 and 190 nm. No evidence of intracellular collagen synthesis by the tumor cells was found. The presence of 'amianthoid' fibers does /lot seem to carry any prognostic signiflcance.
Introduction Meningioma is a frequent tumor constituing around 13% to 19% of primary neoplasms of the central nervous system 7 • Most ca ses are benign and of histologieal grade 1. The histopathologieal features of meningioma are well known and the diagnosis is usually made without diffieulties. Oeeasionally, eertain variants induee misdiagnosis because of subtle variations of their histologie aspeet. Moreover, some of these features may have an important morphogenetie andlor prognostie signifieanee. The main histologie al variants are: meningothelial, fibroblastie, transitional, psammomatous, angiomatous, papillomatous, hemangioperieytie, and anaplastie7 , and of these, the so-ealled hemangioperieytie variant of the angioblastie type, the papillomatous variant and the anaplastie one have an aggressive biologie behavior. The present report coneerns a very unusual variant of meningothelial meningioma showing the so-ealled 'amianthoid' fibers. Case Report A previously healths 48-year-old woman presented with ahistory of 1 week of sudden onset of headaehe, nausea, 0344-033 g/92/() 188-0890$3.5010
and vomiting. Clinieal examination revealed a left hemiparesis, bilateral papillary edema and meningeal signs. A brain CT sean showed a parasagital of 3.5 X 5 em in diameter in the right parietal area, 1 em near the median line, partially eollapsing the right lateral ventricle. At surgery, the duramater appeared protuberant and an extensive subdural hematoma partially overlying the tumor mass was evident. Postoperatively, partial remission of hemiparesis was observed and no evidenee of residual tumor has been recorded four months after the diagnosis.
Material and Methods Tumof sam pies wefl" fixed in 10% neutral formalin and routinely proeessed. Special stains included van Gieson's trichrome and phosphotungstic acid hematoxylin. From the formalin-fixed material 1 mm 3 sam pies were recuperated for clectron microscopy. They were postfixed in 050 4 and embedded in Epon 812. Toluidinc bluc-staincd semithin sections were obtained for orientation. Thin sections were stained wirh uranyl acetate and lead citrate and examined under a Zciss 109 electron nllcroscope. @
1992 by Gustav Fischer Verlag, Sttrttgart
Men ingothel ial Meningioma . 89 1
Results Light Microscopic Findings
The tumor was composed of l arge cells arranged in nests and small syncitialmasses. The cytoplasm was abundant, pale eosinophilic with pood y defined oudines. The nuclei were round to oval with small basophilic nucleoli and loose chromatin. Nuclear pseudoinclusions were easily found. Occasionally, larger and hyperchromatic nuclei were apparent, but neither necrosis nor atypical mitoses were found. The stro ma was scant. Rounded, deeply eosinophilic and fibrillary areas were conspicuous. They measured from 20 to 300 ~m in diameter disclosing a fibrillary arrangement and focally a starry appearance (Fig. 1 ). Some were located aro und sm all dilated blood vessels, whereas others were among tumor nests (Fig. 2). Van Gieson's trichrome s howed an intense red staining and a characteristic fibrillary appea rance. At the periphery of these foci, yellowish, amorphous material was also observed. Psammoma bodies and calcifications were not identified. Electron Microscopic F indings
Fig. 1. Meningotheli al m enill gioma w ith t ypieal stellate foei oE 'ami anthoid' fibers among tum o r cells. Van Gieson's trieh ro me, x 200. .
Tumor cells disclosed numero us interdigitating cytoplasmic projections and frequent desmosome-like and hemidesmosome-like intercellular junctions. The Golgi apparatus was well developed and dispersed cisternae o f ro ugh endoplasmic reticulum were also found. Mitochondria and lysosomes were s cant. The nuclei showed cytoplasmic invaginations and dense nucleoli. Intracytoplasmic intermediate filaments were occasionally observed. The fibrillary bodies were composed of disorderly arranged and interwaving mature collagen fibrils (Fig. 3). These showed the characteristic cross-striations of 65 nm periodicity of collagen fibrils. Fibrils' width varied from 40 to 190 nm, most of them b eing around 120 nm. Thinner
Fig.2. 'Amianthoid' fib er morphogenesis around blood vessels. (a) Condensation and deposition aro und a dilated blood vessel, (b) obliteration of vessel lumen, an d (c) final stage of full y develo ped body. Van Gieson 's t richrome, x 500.
Fig. 3. Electron microphotograph of 'amianthoid' fibers composed of mature collagen fibrils, disorderly arranged and of variable width. Uranyl acetate'and lead citrate, x 6,000.
Fig. 4. Thinner filaments intermingled with mature collagen fibrils at th e periphery of an 'amianthoid' fiber. Uranyl acetate and lead citrate, x 30,000.
Meningothelial Meningioma . 893
filaments around 10 nm in width were also found, especially at the periphery of the fibrillary body (Fig. 4). Discussion 'Amianthoid' fibers are composed of haphazardly arranged mature collagen fibrils, some of which are abnormally thicker. These fibers were first described in 'fibrillary transformation', 'fibrillary degeneration', or 'asbestoid degeneration' as an age-related regressive change of hyaline cartilage3 . It is frequent in degenerative diseases such as osteoarthritis and emphysema. The presence of 'amianthoid' fibers has been recorded in a variety of neoplasms, i.e. chondrosarcoma2 , synovia I sarcoma 6, malignant schwannoma6 , palisaded myofibroblastoma 8,9, neuroendocrine neoplasms 5 , and in a very unusual tumor called 'amianthioma' 1. In all these cases 'amianthoid' fibers have been described as mature collagen fibrils of varying width up to 1000 nm, randomly arranged, forming stellate bodies, occasionally perivascular, and intermingled with normal collagen fibrils. The so-called 'amianthioma' is a benign tumor of the skin and subcutaneous tissue, adjacent to the tibialis anterior musde, described in a 42-year-old woman and characterized by sheets of epithelioid cells in a wellvascularized stroma and with multiple 'amianthoid' bodies 1• Ultrastructurally, the tumor cells showed cytoplasmic projections, nudear indenqltions, with moderate amounts of organelles and occassional desmosome-like intercellular junctions. The 'amianthoid' fibers were identified as aggregates of dense collagen fibrils with characteristic 68 nm periodicity. They were described as thick fibers but the width was not recorded. Collagen fibrils depicted in Fig. 5 of Dr. Connolly's report measure up to 350 nm in width. The above-mentioned features of the 'amianthioma' are morphologically very similar to the tumor of the present case. The histogenesis of 'amianthoid' fibers is still unknown. Many authors believe that these fibers originate from a passive phenomenon of aggregation after age-related anoxic injury 3. It is not dear whether this apposition is due to depletion of glycosaminoglycanes and water of the matrix or whether the formation of hydrogen-cross linkes hold the component fibrils together 3 . However, this hypothesis does not satisfactorily explain the rather usual appearance of 'amianthoid' fibers around blood vessels in aseries of neoplasms 3 ,8. 'Amianthoid' fibers associated with synovial sarcoma and malignant schwannoma are dosely related to tumor cells showing ultrastructural
features suggestive of collagen synthesis. These signs include well developed Golgi apparatus, prominent rough endoplasmic reticulum with osmiophilic material in some dilated cisternae, dose apposition of tumor cell cytoplasm and the fibers, and even intracytoplasmic collagen fibrils 6• Thus, the possibility of active collagen synthesis by the tumor cells must also be seriously considered. In the present case no evidence of intracellular collagen synthesis was found. Harkin and Leonard4 reported a similar case in a 34-year-old woman with an intradural meningioma of the lumbar spinal cord. Histologically, this neoplasm also showed numerous eosinophilic and partially calcified nodules, which ultrastructurally corresponded to thick collagen fibrils similar to 'amianthoid' fibers. No evidence of fiber synthesis by the tumor cells was recorded. The tumor evolved without recurrence after two years of follow up. Morphologic evidence of malignancy was not found in our case and the patient is weil and alive without residual tumor 4 months after surgery. In our opinion, the presence of 'amianthoid' fibers does not carry any prognostic significance.
References 1 Connolly CE (1981) 'Crystalline' collagen production by an unusual benign soft tissue tumor ('amianthioma'). Histopathology 5: 11-20 2 Ghadially FN, Lalonde JMA, Yong NK (1980) Amianthoid fibers in a chondrosarcoma. J Pathol130: 147-151 3 Ghadially FN (1982) Ultrastructural Pathology of the Cell and Matrix. 2nd edition, Butterworths, London 4 Harkin JC, Leonard GL (1988) Abnormal amianthoid collagen fibers in meningioma. Acta Neuropatol 76: 638-639 5 Hull MT, Warfel KA. Ultrastructure of abnormal collagen in human tumors. Ultrastruct Pathol 10: 293-301 6 Orenstein JM (1983) Amianthoid fibers in a synovial sarcoma and a malignant schwannoma. Ultrastruct Pathol 4: 163-176 7 Russell OS, Rubinstein LJ (1989) Pathology of Tumours of the Nervous System. 5th edition, Williams & Wilkins, Baltimore 8 Suster S, Rosai (1989) Intranodal hemorrhagic spindle-cell tumor with 'amianthoid' fibers. Report of six cases of a distinctive mesenchymal neoplasm of the inguinal region that simulates Kaposi's sarcoma. Am J Surg Pathol13: 347-357 9 Weiss SM, Gnepp OR, Bratthauer GL (1':}89) Palisaded myofibroblastoma. A benign mesenchymal tumor of lymph node. Am J Surg Pathol13: 341-346
Received February 18, 1991 . Accepted in revised form August 29, 1991
Key words: Meningioma - Amianthoid fibers - Brain tumor - Collagen fibrils Sergio Gonzalez B., M.O. PhO., Oepartment of Pathology, Esc. de Medicina, Universidad Catolica de Chile, Casilla 114-0, Santiago, Chile
