J Neurosurg Pediatrics 14:155–159, 2014 ©AANS, 2014
Meningeal fibroma: a rare meningioma mimic Report of 2 cases Aanchal Kakkar, M.D.,1 Mehar C. Sharma, M.D.,1 Nishant Goyal, M.B.B.S., 2 Chitra Sarkar, M.D.,1 Vaishali Suri, M.D.,1 Ajay Garg, M.D., 3 Shashank S. Kale, M.Ch., 2 and Ashish Suri, M.Ch. 2 Departments of 1Pathology, 2Neurosurgery, and 3Neuroradiology, All India Institute of Medical Sciences, New Delhi, India Meningeal fibromas are rare intracranial tumors that mimic meningiomas radiologically as well as histologically. The authors report 2 cases of meningeal fibroma with detailed clinical, radiological, histopathological, and immunohistochemical features, and discuss the differential diagnosis of this entity. Knowledge of this rare tumor is essential for pathologists to be able distinguish it from more common meningeal tumors, especially in younger patients. This knowledge is also essential for neurosurgeons, as incomplete resection may lead to tumor recurrence, and such patients require close follow-up. (http://thejns.org/doi/abs/10.3171/2014.5.PEDS13556)
Key Words • fibroma • meningeal tumor • meningioma • oncology • solitary fibrous tumor • intracranial • mesenchymal
F
proliferative lesions arising from meningeal mesenchymal tissue are extremely rare and include fibromatosis, solitary fibrous tumor (SFT), inflammatory myofibroblastic tumor, fibroma, and cranial fasciitis.1 The histological appearance of these lesions is similar to more common tumors such as meningiomas, and therefore they pose a challenge to the diagnostic skills of the pathologist. We report 2 cases of meningeal fibroma, one in a 15-year-old boy and another in an 8-year-old boy, both of which mimicked meningioma on radiological as well as on histological examination, causing a diagnostic dilemma. ibrous
Case Reports
Case 1. A 15-year-old boy complained of intermitAbbreviations used in this paper: EMA = epithelial membrane antigen; GFAP = glial fibrillary acidic protein; SFT = solitary fibrous tumor; SMA = smooth muscle actin.
J Neurosurg: Pediatrics / Volume 14 / August 2014
tent headache and vomiting for 3 months. His parents had noted changes in his personality and behavior over this period. On examination, there was no evidence of any sensorimotor deficits or any stigmata of neurofibromatosis. Magnetic resonance imaging revealed a large, heterogeneously enhancing mass lesion in the frontotemporoparietal region, suggestive of a meningioma (Fig. 1). The patient underwent a right frontoparietal craniotomy and gross-total excision of the tumor. Intraoperatively, a grayish-white, hard, extraaxial mass with minimal vascularity was noted, attached to the falx. The tumor was excised completely, along with its falcine attachment (Simpson Grade I excision) and was submitted for histopathological evaluation. The patient remains recurrence-free 3 years after the surgery. Case 2. An 8-year-old boy presented with a history of intermittent headache and abnormal behavior, includThis article contains some figures that are displayed in color online but in black-and-white in the print edition.
155
A. Kakkar et al.
Fig. 1. Case 1. Axial contrast-enhanced (left) and bone window (right) CT scans show a well-defined, homogeneously hyperdense extraaxial lesion in the left temporoparietal region with perilesional edema, overlying periosteal reaction, and new bone formation (arrow, right) from the inner table of the skull. In the anterior portion of the lesion, hypodensity (asterisk, left) secondary to CSF loculation/cyst is noted.
ing hyperactivity and nonsensical speech, for 1 year. He had undergone operations twice at another hospital, after which he had remained symptomatic postoperatively. On both the previous occasions, a histopathological diagnosis of WHO Grade I fibroblastic meningioma had been made. Preoperative MRI of his head showed a well-defined falcine region mass that was hypointense on T2-weighted images and showed peripheral dense enhancement on T1-weighted images with contrast administration. There was no evidence of calcification. Repeat imaging revealed a residual tumor (Fig. 2). The tumor was approached through a bifrontal craniotomy. Intraoperatively, a welldemarcated, firm, lobulated, poorly vascularized tumor was noted attached to the middle third of the falx cerebri, which was reaching up to the base of the falx, more on the right side. Simpson Grade II tumor excision was achieved, and the operative specimen was submitted for histopathological examination. Sections from the primary tumor stained with H & E were also reviewed. The patient was followed up for a period of 1 year, during which time no further recurrence or metastasis occurred.
Pathological Examination. Tumor tissue was fixed in 10% neutral-buffered formalin, routinely processed, and paraffin embedded. Five-micron-thick sections were cut for routine H & E staining and immunohistochemical analysis. A labeled streptavidin biotin kit (Universal, Dako) was used as a detection system. Antigen retrieval was performed in a microwave oven using citrate buffer at pH 6.0 for all antibodies. Monoclonal antibodies against vimentin (Diagnostic BioSystems, 1:100), epithelial membrane antigen (EMA; Dako, 1:100), pan cytokeratin (Neomarkers, 1:200), claudin-1 (Neomarkers, 1:50), smooth muscle actin (SMA; Dako, 1:50), progesterone receptors (Neomarkers, 1:50), estrogen receptors (Neomarkers, 1:50), CD34 (Dako, 1:100), bcl-2 (Neomarkers, 1:100), CD99 (Dako, 1:100), desmin (Dako, 1:50), glial fibrillary acidic protein (GFAP; Dako, 1:1500), beta catenin (BD Transduction, 1:200), p53 protein (Santa Cruz Biotechnology, 1:1000), and proliferation marker MIB-1 (Dako, 1:200) were used. For assessing the MIB156
Fig. 2. Case 2. An axial T2-weighted MR image shows a well-defined hypointense mass in the region of the floor of the anterior cranial fossa (A). No foci of calcifications are observed on a T2-weighted gradient echo image (B). On contrast administration, the peripheral portion of the tumor shows dense contrast enhancement on a T1-weighted image (C). A postoperative T1-weighted image after Gd administration shows residual tumor (D).
1 labeling index, at least 500 cells were counted using a 1-square-mm eyepiece pinhole. For each batch, appropriate positive and negative controls were taken. Electron microscopic examination was performed on paraffin-embedded tumor tissue, after deparaffinization, rehydration, and postfixation in osmium tetroxide. Microscopic Examination. Sections stained with H & E from tumors from both patients showed similar features (Fig. 3). The tumors were sparsely cellular, composed of elongated spindled-shaped cells with a scant to moderate amount of pale eosinophilic cytoplasm, and normochromatic oval to elongated nuclei with delicate chromatin and inconspicuous nucleoli. The tumor cells were arranged in long parallel fascicles that were embedded in a densely collagenized matrix. Areas of hyalinization were present and were more prominent around blood vessels. Sections from both cases showed focal myxoid change in the stroma. The tumor cells did not demonstrate nuclear atypia, pleomorphism, mitoses, or areas of necrosis. There was no evidence of meningothelial differentiation in the form of whorl formation or sheeting of the tumor cells. Mast cells were observed interspersed between the tumor cells. Review of sections prepared from tumors excised at the first and second surgeries in Case 2 showed similar histomorphological features. The tumor cells were immunopositive for vimentin; J Neurosurg: Pediatrics / Volume 14 / August 2014
Meningeal fibroma
Fig. 3. Photomicrographs showing tumor cells in long intersecting fascicles (A and B) with areas of hyalinization (C), focal myxoid change (D), and thick bundles of collagen in the stroma (E). High magnification shows bland spindle-shaped cells with elongated nuclei (F), perivascular hyalinization (G), and interspersed mast cells (H). H & E, original magnification ×40 (A), ×100 (B and C), ×200 (D and E), and ×400 (F–H).
however, they were immunonegative for EMA, S100 protein, claudin-1, estrogen receptors, progesterone receptors, CD34, CD99, bcl-2, beta catenin, desmin, SMA, pan cytokeratin, and GFAP (Fig. 4). The MIB-1 labeling index was less than 1% in both tumors, and no immuJ Neurosurg: Pediatrics / Volume 14 / August 2014
nopositivity for p53 protein was noted. Ultrastructural examination (Fig. 5) of paraffin-embedded tumor tissue from both cases showed the presence of artifacts; however, the features were sufficient to recognize the tumor cells as fibroblasts. Spindle-shaped tumor cells with 157
A. Kakkar et al.
Fig. 4. Tumor cells in both cases were found to be immunopositive for vimentin (left), and the MIB-1 labeling index was less than 1% (right). Original magnification ×400 (left) and ×200 (right).
elongated nuclei, some of which appeared indented, and abundant dilated rough endoplasmic reticulum were identified. Some of the cells showed the presence of elongated processes. Bundles of collagen fibers were present in the extracellular matrix. Intercellular junctions and interdigitations were not observed, excluding the possibility of a meningothelial origin.
Discussion
Intracranial fibromas are rare, benign, fibrous lesions that arise from the meninges or from within the brain parenchyma.1,4,5 Less than 20 such cases have been described to date, and their incidence remains unknown.1,2,4,5,7,9,11–13 At our institute, they accounted for 0.12% (2/1648) of all meningeal tumors excised over a 10-year period. Intracranial fibroma was first described in the English literature by Koos et al. in 1971 in an 11-month-old boy.4 These fibromas are frequently noted in the first 2 decades of life, and show a male preponderance.12 These tumors are usually bulky, well-circumscribed masses that, on histological examination, are found to be composed of elongated spindle cells in a dense, eosinophilic, hyalinized collagenous matrix.1 Due to the rarity of these tumors, no definite management protocol is defined for meningeal fibromas. Because these tumors are benign lesions, complete resection is curative. However, incomplete resection can lead to recurrence or regrowth of the tumor, as noted in one of our cases. The differential diagnoses of meningeal fibroma include meningioma, SFT, fibromatosis, cranial fasciitis, meningeal myxoma, and meningeal glioma (Table 1). While psammomatous calcification and osseous and chon-
droid metaplasia may be encountered in these tumors,1 the absence of whorls and meningothelial features helps to distinguish them from fibroblastic meningiomas.12 Immunoreactivity with EMA, claudin-1, S100 protein, and progesterone receptors in meningiomas further aids in this distinction.12 Another close differential diagnosis is SFT. These tumors also arise from the meninges, but are usually observed in adults.1 Solitary fibrous tumors are more cellular than fibromas, and are composed of interlacing fascicles of spindle cells rather than long parallel fascicles.1 They are immunopositive for CD34, CD99 and bcl-2, while fibromas are negative for these markers.12 Meningeal gliomas are extremely rare; the absence of collagen accompanied by immunopositivity for GFAP helps to differentiate between the two tumors.12 Fibromatosis is a histologically benign but locally invasive condition involving the dura, but it has infiltrative margins, whereas fibromas are well circumscribed.10 Fibromatosis may occur de novo or at the site of previous surgery or trauma.6 Intracranial myxomas are rare lesions that arise from the skull bones and may show attachment to the dura. Radiologically, they are usually limited to the inner and outer tables of the skull, while histologically, they are typified by a loose myxoid matrix containing spindled- to stellate-shaped cells with minimal pleomorphism.8 Cranial fasciitis is a reactive proliferation of fibroblastic and myofibroblastic cells in a variably hyalinized and myxoid stroma, which involves the soft tissue of the scalp and adjacent cranium, and may extend to involve the dura. Its predilection for the first 6 years of life, presence of a lytic skull lesion, prominent myxoid matrix, and inflammatory cell infiltrate on histology help to distinguish it from meningeal fibroma.3 Nonmeningothelial tumors of the meninges, including fibromas, are much less common than meningiomas. Knowledge of these entities is essential for pathologists to include them in the differential diagnosis of meningiomas, especially in younger patients; this knowledge is also essential for neurosurgeons because incomplete resection may lead to tumor recurrence, and these patients need to be closely followed up. Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
Fig. 5. Electron photomicrographs showing a tumor cell with elongated nucleus and dilated endoplasmic reticulum (asterisk, A). Higher magnification shows an indentation in the nucleus and margination of chromatin (B). Bundles of collagen fibers are noted around the tumor cell (C).
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J Neurosurg: Pediatrics / Volume 14 / August 2014
Meningeal fibroma TABLE 1: Immunohistochemical panel for differential diagnosis of fibroma from other meningeal tumors* Tumor
Vimentin
EMA
S100
SMA
CD34
CD99
Bcl-2
Claudin-1
PR
GFAP
fibroma meningioma SFT glioma
+ + + +
− + − −
− +/− +
focal +/− − focal +/− −
− − + −
− − + −
− − + −
− + − −
− + − −
− − − +
* PR = progesterone receptors; + = positive; − = negative. Author contributions to the study and manuscript preparation include the following. Conception and design: Sharma, Kakkar. Acquisition of data: Kakkar, Goyal, Kale, A Suri. Analysis and interpretation of data: Sharma, Kakkar, Sarkar, V Suri, Garg. Drafting the article: Kakkar, Goyal. Critically revising the article: Sharma. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Sharma. References 1. Ceyhan K, Berk Q, Caglar S, Sürücü S: A calcifying fibroma of the meninges report of a case and review of the literature. Pathol Res Pract 196:747–752, 2000 2. Hirano A, Llena JF, Chung HD: Fine structure of a cerebellar “fibroma.” Acta Neuropathol 32:175–186, 1975 3. Keyserling HF, Castillo M, Smith JK: Cranial fasciitis of childhood. AJNR Am J Neuroradiol 24:1465–1467, 2003 4. Koos WT, Jellinger K, Sunder-Plassmann M: Intracerebral fibroma in an 11-month-old infant. Case report. J Neurosurg 35:77–81, 1971 5. Llena JF, Chung HD, Hirano A, Feiring EH, Zimmerman HM: Intracerebellar “fibroma.” Case report. J Neurosurg 43:98– 101, 1975 6. Mitchell A, Scheithauer BW, Ebersold MJ, Forbes GS: Intracranial fibromatosis. Neurosurgery 29:123–126, 1991 7. Mooney JE, Papasozomenos SC: Leptomeningeal fibroma. Clin Neuropathol 15:92–95, 1996 8. Oruckaptan HH, Sarac S, Gedikoglu G: Primary intracranial
J Neurosurg: Pediatrics / Volume 14 / August 2014
myxoma of the lateral skull base: a rare entity in clinical practice. Turk Neurosurg 20:86–89, 2010 9. Palma L, Spagnoli LG, Yusuf MA: Intracerebral fibroma: light and electron microscopic study. Acta Neurochir (Wien) 77:152–156, 1985 10. Paulus W, Scheithauer BW, Perry A: Mesenchymal, non-meningothelial tumours, in Louis DN, Ohgaki H, Wiestler OD, et al (eds): WHO Classification of Tumours of the Central Nervous System, ed 4. Lyon: IARC Press, 2007, pp 173–177 11. Pollack LF, Hamilton RL, Fitz C, Orenstein DM: An intrasylvian “fibroma” in a child with cystic fibrosis: case report. Neurosurgery 46:744–747, 2000 12. Reyes-Mugica M, Chou P, Gonzalez-Crussi F, Tomita T: Fibroma of the meninges in a child: immunohistological and ultrastructural study. Case report. J Neurosurg 76:143–147, 1992 13. Wright DH, Naul LG, Hise JH, Bauserman SC: Intraventricular fibroma: MR and pathologic comparison. AJNR Am J Neuroradiol 14:491–492, 1993 Manuscript submitted October 17, 2013. Accepted May 7, 2014. Please include this information when citing this paper: published online June 20, 2014; DOI: 10.3171/2014.5.PEDS13556. Address correspondence to: Mehar Chand Sharma, M.D., F.R.C.Path., Department of Neuropathology, All India Institute of Medical Sciences, New Delhi 110029, India. email: sharmamehar@ yahoo.co.in.
159
Meningeal fibroma: a rare meningioma mimic Report of 2 cases Aanchal Kakkar, M.D.,1 Mehar C. Sharma, M.D.,1 Nishant Goyal, M.B.B.S., 2 Chitra Sarkar, M.D.,1 Vaishali Suri, M.D.,1 Ajay Garg, M.D., 3 Shashank S. Kale, M.Ch., 2 and Ashish Suri, M.Ch. 2 Departments of 1Pathology, 2Neurosurgery, and 3Neuroradiology, All India Institute of Medical Sciences, New Delhi, India Meningeal fibromas are rare intracranial tumors that mimic meningiomas radiologically as well as histologically. The authors report 2 cases of meningeal fibroma with detailed clinical, radiological, histopathological, and immunohistochemical features, and discuss the differential diagnosis of this entity. Knowledge of this rare tumor is essential for pathologists to be able distinguish it from more common meningeal tumors, especially in younger patients. This knowledge is also essential for neurosurgeons, as incomplete resection may lead to tumor recurrence, and such patients require close follow-up. (http://thejns.org/doi/abs/10.3171/2014.5.PEDS13556)
Key Words • fibroma • meningeal tumor • meningioma • oncology • solitary fibrous tumor • intracranial • mesenchymal
F
proliferative lesions arising from meningeal mesenchymal tissue are extremely rare and include fibromatosis, solitary fibrous tumor (SFT), inflammatory myofibroblastic tumor, fibroma, and cranial fasciitis.1 The histological appearance of these lesions is similar to more common tumors such as meningiomas, and therefore they pose a challenge to the diagnostic skills of the pathologist. We report 2 cases of meningeal fibroma, one in a 15-year-old boy and another in an 8-year-old boy, both of which mimicked meningioma on radiological as well as on histological examination, causing a diagnostic dilemma. ibrous
Case Reports
Case 1. A 15-year-old boy complained of intermitAbbreviations used in this paper: EMA = epithelial membrane antigen; GFAP = glial fibrillary acidic protein; SFT = solitary fibrous tumor; SMA = smooth muscle actin.
J Neurosurg: Pediatrics / Volume 14 / August 2014
tent headache and vomiting for 3 months. His parents had noted changes in his personality and behavior over this period. On examination, there was no evidence of any sensorimotor deficits or any stigmata of neurofibromatosis. Magnetic resonance imaging revealed a large, heterogeneously enhancing mass lesion in the frontotemporoparietal region, suggestive of a meningioma (Fig. 1). The patient underwent a right frontoparietal craniotomy and gross-total excision of the tumor. Intraoperatively, a grayish-white, hard, extraaxial mass with minimal vascularity was noted, attached to the falx. The tumor was excised completely, along with its falcine attachment (Simpson Grade I excision) and was submitted for histopathological evaluation. The patient remains recurrence-free 3 years after the surgery. Case 2. An 8-year-old boy presented with a history of intermittent headache and abnormal behavior, includThis article contains some figures that are displayed in color online but in black-and-white in the print edition.
155
A. Kakkar et al.
Fig. 1. Case 1. Axial contrast-enhanced (left) and bone window (right) CT scans show a well-defined, homogeneously hyperdense extraaxial lesion in the left temporoparietal region with perilesional edema, overlying periosteal reaction, and new bone formation (arrow, right) from the inner table of the skull. In the anterior portion of the lesion, hypodensity (asterisk, left) secondary to CSF loculation/cyst is noted.
ing hyperactivity and nonsensical speech, for 1 year. He had undergone operations twice at another hospital, after which he had remained symptomatic postoperatively. On both the previous occasions, a histopathological diagnosis of WHO Grade I fibroblastic meningioma had been made. Preoperative MRI of his head showed a well-defined falcine region mass that was hypointense on T2-weighted images and showed peripheral dense enhancement on T1-weighted images with contrast administration. There was no evidence of calcification. Repeat imaging revealed a residual tumor (Fig. 2). The tumor was approached through a bifrontal craniotomy. Intraoperatively, a welldemarcated, firm, lobulated, poorly vascularized tumor was noted attached to the middle third of the falx cerebri, which was reaching up to the base of the falx, more on the right side. Simpson Grade II tumor excision was achieved, and the operative specimen was submitted for histopathological examination. Sections from the primary tumor stained with H & E were also reviewed. The patient was followed up for a period of 1 year, during which time no further recurrence or metastasis occurred.
Pathological Examination. Tumor tissue was fixed in 10% neutral-buffered formalin, routinely processed, and paraffin embedded. Five-micron-thick sections were cut for routine H & E staining and immunohistochemical analysis. A labeled streptavidin biotin kit (Universal, Dako) was used as a detection system. Antigen retrieval was performed in a microwave oven using citrate buffer at pH 6.0 for all antibodies. Monoclonal antibodies against vimentin (Diagnostic BioSystems, 1:100), epithelial membrane antigen (EMA; Dako, 1:100), pan cytokeratin (Neomarkers, 1:200), claudin-1 (Neomarkers, 1:50), smooth muscle actin (SMA; Dako, 1:50), progesterone receptors (Neomarkers, 1:50), estrogen receptors (Neomarkers, 1:50), CD34 (Dako, 1:100), bcl-2 (Neomarkers, 1:100), CD99 (Dako, 1:100), desmin (Dako, 1:50), glial fibrillary acidic protein (GFAP; Dako, 1:1500), beta catenin (BD Transduction, 1:200), p53 protein (Santa Cruz Biotechnology, 1:1000), and proliferation marker MIB-1 (Dako, 1:200) were used. For assessing the MIB156
Fig. 2. Case 2. An axial T2-weighted MR image shows a well-defined hypointense mass in the region of the floor of the anterior cranial fossa (A). No foci of calcifications are observed on a T2-weighted gradient echo image (B). On contrast administration, the peripheral portion of the tumor shows dense contrast enhancement on a T1-weighted image (C). A postoperative T1-weighted image after Gd administration shows residual tumor (D).
1 labeling index, at least 500 cells were counted using a 1-square-mm eyepiece pinhole. For each batch, appropriate positive and negative controls were taken. Electron microscopic examination was performed on paraffin-embedded tumor tissue, after deparaffinization, rehydration, and postfixation in osmium tetroxide. Microscopic Examination. Sections stained with H & E from tumors from both patients showed similar features (Fig. 3). The tumors were sparsely cellular, composed of elongated spindled-shaped cells with a scant to moderate amount of pale eosinophilic cytoplasm, and normochromatic oval to elongated nuclei with delicate chromatin and inconspicuous nucleoli. The tumor cells were arranged in long parallel fascicles that were embedded in a densely collagenized matrix. Areas of hyalinization were present and were more prominent around blood vessels. Sections from both cases showed focal myxoid change in the stroma. The tumor cells did not demonstrate nuclear atypia, pleomorphism, mitoses, or areas of necrosis. There was no evidence of meningothelial differentiation in the form of whorl formation or sheeting of the tumor cells. Mast cells were observed interspersed between the tumor cells. Review of sections prepared from tumors excised at the first and second surgeries in Case 2 showed similar histomorphological features. The tumor cells were immunopositive for vimentin; J Neurosurg: Pediatrics / Volume 14 / August 2014
Meningeal fibroma
Fig. 3. Photomicrographs showing tumor cells in long intersecting fascicles (A and B) with areas of hyalinization (C), focal myxoid change (D), and thick bundles of collagen in the stroma (E). High magnification shows bland spindle-shaped cells with elongated nuclei (F), perivascular hyalinization (G), and interspersed mast cells (H). H & E, original magnification ×40 (A), ×100 (B and C), ×200 (D and E), and ×400 (F–H).
however, they were immunonegative for EMA, S100 protein, claudin-1, estrogen receptors, progesterone receptors, CD34, CD99, bcl-2, beta catenin, desmin, SMA, pan cytokeratin, and GFAP (Fig. 4). The MIB-1 labeling index was less than 1% in both tumors, and no immuJ Neurosurg: Pediatrics / Volume 14 / August 2014
nopositivity for p53 protein was noted. Ultrastructural examination (Fig. 5) of paraffin-embedded tumor tissue from both cases showed the presence of artifacts; however, the features were sufficient to recognize the tumor cells as fibroblasts. Spindle-shaped tumor cells with 157
A. Kakkar et al.
Fig. 4. Tumor cells in both cases were found to be immunopositive for vimentin (left), and the MIB-1 labeling index was less than 1% (right). Original magnification ×400 (left) and ×200 (right).
elongated nuclei, some of which appeared indented, and abundant dilated rough endoplasmic reticulum were identified. Some of the cells showed the presence of elongated processes. Bundles of collagen fibers were present in the extracellular matrix. Intercellular junctions and interdigitations were not observed, excluding the possibility of a meningothelial origin.
Discussion
Intracranial fibromas are rare, benign, fibrous lesions that arise from the meninges or from within the brain parenchyma.1,4,5 Less than 20 such cases have been described to date, and their incidence remains unknown.1,2,4,5,7,9,11–13 At our institute, they accounted for 0.12% (2/1648) of all meningeal tumors excised over a 10-year period. Intracranial fibroma was first described in the English literature by Koos et al. in 1971 in an 11-month-old boy.4 These fibromas are frequently noted in the first 2 decades of life, and show a male preponderance.12 These tumors are usually bulky, well-circumscribed masses that, on histological examination, are found to be composed of elongated spindle cells in a dense, eosinophilic, hyalinized collagenous matrix.1 Due to the rarity of these tumors, no definite management protocol is defined for meningeal fibromas. Because these tumors are benign lesions, complete resection is curative. However, incomplete resection can lead to recurrence or regrowth of the tumor, as noted in one of our cases. The differential diagnoses of meningeal fibroma include meningioma, SFT, fibromatosis, cranial fasciitis, meningeal myxoma, and meningeal glioma (Table 1). While psammomatous calcification and osseous and chon-
droid metaplasia may be encountered in these tumors,1 the absence of whorls and meningothelial features helps to distinguish them from fibroblastic meningiomas.12 Immunoreactivity with EMA, claudin-1, S100 protein, and progesterone receptors in meningiomas further aids in this distinction.12 Another close differential diagnosis is SFT. These tumors also arise from the meninges, but are usually observed in adults.1 Solitary fibrous tumors are more cellular than fibromas, and are composed of interlacing fascicles of spindle cells rather than long parallel fascicles.1 They are immunopositive for CD34, CD99 and bcl-2, while fibromas are negative for these markers.12 Meningeal gliomas are extremely rare; the absence of collagen accompanied by immunopositivity for GFAP helps to differentiate between the two tumors.12 Fibromatosis is a histologically benign but locally invasive condition involving the dura, but it has infiltrative margins, whereas fibromas are well circumscribed.10 Fibromatosis may occur de novo or at the site of previous surgery or trauma.6 Intracranial myxomas are rare lesions that arise from the skull bones and may show attachment to the dura. Radiologically, they are usually limited to the inner and outer tables of the skull, while histologically, they are typified by a loose myxoid matrix containing spindled- to stellate-shaped cells with minimal pleomorphism.8 Cranial fasciitis is a reactive proliferation of fibroblastic and myofibroblastic cells in a variably hyalinized and myxoid stroma, which involves the soft tissue of the scalp and adjacent cranium, and may extend to involve the dura. Its predilection for the first 6 years of life, presence of a lytic skull lesion, prominent myxoid matrix, and inflammatory cell infiltrate on histology help to distinguish it from meningeal fibroma.3 Nonmeningothelial tumors of the meninges, including fibromas, are much less common than meningiomas. Knowledge of these entities is essential for pathologists to include them in the differential diagnosis of meningiomas, especially in younger patients; this knowledge is also essential for neurosurgeons because incomplete resection may lead to tumor recurrence, and these patients need to be closely followed up. Disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.
Fig. 5. Electron photomicrographs showing a tumor cell with elongated nucleus and dilated endoplasmic reticulum (asterisk, A). Higher magnification shows an indentation in the nucleus and margination of chromatin (B). Bundles of collagen fibers are noted around the tumor cell (C).
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J Neurosurg: Pediatrics / Volume 14 / August 2014
Meningeal fibroma TABLE 1: Immunohistochemical panel for differential diagnosis of fibroma from other meningeal tumors* Tumor
Vimentin
EMA
S100
SMA
CD34
CD99
Bcl-2
Claudin-1
PR
GFAP
fibroma meningioma SFT glioma
+ + + +
− + − −
− +/− +
focal +/− − focal +/− −
− − + −
− − + −
− − + −
− + − −
− + − −
− − − +
* PR = progesterone receptors; + = positive; − = negative. Author contributions to the study and manuscript preparation include the following. Conception and design: Sharma, Kakkar. Acquisition of data: Kakkar, Goyal, Kale, A Suri. Analysis and interpretation of data: Sharma, Kakkar, Sarkar, V Suri, Garg. Drafting the article: Kakkar, Goyal. Critically revising the article: Sharma. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Sharma. References 1. Ceyhan K, Berk Q, Caglar S, Sürücü S: A calcifying fibroma of the meninges report of a case and review of the literature. Pathol Res Pract 196:747–752, 2000 2. Hirano A, Llena JF, Chung HD: Fine structure of a cerebellar “fibroma.” Acta Neuropathol 32:175–186, 1975 3. Keyserling HF, Castillo M, Smith JK: Cranial fasciitis of childhood. AJNR Am J Neuroradiol 24:1465–1467, 2003 4. Koos WT, Jellinger K, Sunder-Plassmann M: Intracerebral fibroma in an 11-month-old infant. Case report. J Neurosurg 35:77–81, 1971 5. Llena JF, Chung HD, Hirano A, Feiring EH, Zimmerman HM: Intracerebellar “fibroma.” Case report. J Neurosurg 43:98– 101, 1975 6. Mitchell A, Scheithauer BW, Ebersold MJ, Forbes GS: Intracranial fibromatosis. Neurosurgery 29:123–126, 1991 7. Mooney JE, Papasozomenos SC: Leptomeningeal fibroma. Clin Neuropathol 15:92–95, 1996 8. Oruckaptan HH, Sarac S, Gedikoglu G: Primary intracranial
J Neurosurg: Pediatrics / Volume 14 / August 2014
myxoma of the lateral skull base: a rare entity in clinical practice. Turk Neurosurg 20:86–89, 2010 9. Palma L, Spagnoli LG, Yusuf MA: Intracerebral fibroma: light and electron microscopic study. Acta Neurochir (Wien) 77:152–156, 1985 10. Paulus W, Scheithauer BW, Perry A: Mesenchymal, non-meningothelial tumours, in Louis DN, Ohgaki H, Wiestler OD, et al (eds): WHO Classification of Tumours of the Central Nervous System, ed 4. Lyon: IARC Press, 2007, pp 173–177 11. Pollack LF, Hamilton RL, Fitz C, Orenstein DM: An intrasylvian “fibroma” in a child with cystic fibrosis: case report. Neurosurgery 46:744–747, 2000 12. Reyes-Mugica M, Chou P, Gonzalez-Crussi F, Tomita T: Fibroma of the meninges in a child: immunohistological and ultrastructural study. Case report. J Neurosurg 76:143–147, 1992 13. Wright DH, Naul LG, Hise JH, Bauserman SC: Intraventricular fibroma: MR and pathologic comparison. AJNR Am J Neuroradiol 14:491–492, 1993 Manuscript submitted October 17, 2013. Accepted May 7, 2014. Please include this information when citing this paper: published online June 20, 2014; DOI: 10.3171/2014.5.PEDS13556. Address correspondence to: Mehar Chand Sharma, M.D., F.R.C.Path., Department of Neuropathology, All India Institute of Medical Sciences, New Delhi 110029, India. email: sharmamehar@ yahoo.co.in.
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