|Year : 2014 | Volume
| Issue : 1 | Page : 200-202
Primary intracranial benign fibrous histiocytoma: Report of an unusual case
Prabal Deb1, Vikram Singh1, Vibha Dutta1, HS Bhatoe2, Vijai Mohan Chandran3
1 Department of Pathology, Armed Forces Medical College, Pune, India
2 Department of Neurosurgery, Command Hospital, Pune, India
3 Department of Radiology, Armed Forces Medical College, Pune, India
|Date of Web Publication||23-Apr-2014|
Department of Pathology, Armed Forces Medical College, Pune
Source of Support: None, Conflict of Interest: None
Benign fibrous histiocytomas (BFH) are neoplasms of the soft tissue and bone composed of fibroblastic and histiocytic components without any nuclear pleomorphism or histological anapalsia. Primary intracranial fibrous histiocytomas are rare entities. In comparison with the malignant counterpart, BFH are more uncommon. We describe a case of a 54-year-old woman, who presented with complaints of headache, giddiness, and gait instability of six months' duration. Magnetic resonance imaging (MRI) studies revealed an extra-axial lesion in the inferior aspect of the left temporal lobe suggestive of en-plaque meningioma. Subsequent histopathological examination of the biopsy sample revealed a benign fibrous histiocytoma, with involvement of the overlying temporal bone. Immunohistochemical analysis showed positivity for vimentin and CD68, with MIB-1 labeling index (MIB-1LI) of 2%, confirming the diagnosis.
良性纤维组织细胞瘤（BFH）是发生于软组织和骨的，由成纤维细胞和组织细胞成分组成但无核多形性或组织学间变的肿瘤。颅内原发性纤维组织细胞瘤是一种罕见的肿瘤。与其对应的恶性肿瘤相比，良性纤维组织细胞瘤更少见。我们描述了一个54岁的女人，主诉持续6个月的头痛，头晕和步态不稳。磁共振成像（MRI）的研究显示，一个轴外病变在左颞叶下部提示脑膜瘤。随后的活检标本的病理检查显示良性纤维组织细胞瘤，上颞骨受累。免疫组化分析表明，波形蛋白和CD68阳性，MIB 1标记指数（MIB 1LI）2%，诊断明确。
Keywords: Benign, dura, fibrous, histiocytoma, meningioma
|How to cite this article:|
Deb P, Singh V, Dutta V, Bhatoe H S, Chandran VM. Primary intracranial benign fibrous histiocytoma: Report of an unusual case. J Can Res Ther 2014;10:200-2
| > Introduction|| |
Fibrous histiocytomas usually occur in the soft tissue and bones, and are rare in the intracranial location. Despite a number of case reports and series pertaining to intracranial malignant fibrous histiocytomas (MFH), , benign fibrous histiocytoma (BFH) remains an uncommon entity with less than 15 published cases, most of which are in the form of isolated case reports. ,,,,,,,,
We report a case of BFH of the left temporal region in a 54-year-old woman. The neuroimaging and intra-operative opinion were of a meningioma. Histopathology, in conjunction with immunohistochemical evaluation and proliferation marker, confirmed the diagnosis.
| > Case Report|| |
A 54-year-old right-handed woman was admitted with complaints of headache, giddiness, and unsteadiness of gait, of six months' duration. There was no history suggestive of raised intracranial tension, visual disturbances, weakness of limbs, stool or urine incontinence, or any sensorineural deficit. On examination, she was afebrile and hemodynamically stable. Her neurological examination revealed normal higher mental functions, without any associated sensory deficit or cerebellar signs. However, her gait was ataxic.
Hematological and biochemical parameters were within normal limits. Magnetic resonance imaging (MRI) brain revealed a well-defined, intensely enhancing extra-axial lesion along the inferior aspect of the left temporal lobe suggestive of an en-plaque meningioma. Axial post-contrast T1 fat-sat image of the brain at the level of the lesion showed a well-defined extra-axial mass arising from the floor and lateral aspect of the anterior half of the left middle cranial fossa causing scalloping of the left temporal squama. There was intense homogeneous post-contrast enhancement, with focal non-enhancing intralesional areas. No dural tails were seen [Figure 1]a.
|Figure 1: (a-h) Axial post-contrast T1 fat-sat image of the brain at the level of the lesion shows a well-defined extra-axial mass arising from the floor and lateral aspect of the anterior half of the left middle cranial fossa causing scalloping of the left temporal squama. There is intense homogeneous post-contrast enhancement, with focal non-enhancing intralesional areas. (a) Photomicrographs showing a cellular tumor with cells arranged in storiform pattern, (b) H and E, ×100) and composed of numerous multinucleated giant cells, (c) H and E, ×40) with invasion of the overlying bone, (d) H and E, ×40). Tumor is reticulin-rich, (e) Reticulin-1 ×40), and cells are immunopositive for vimentin, (f) Vimentin ×400) and CD68, (g) CD68 ×200), with MIB-LI 2%, (h) MIB-1 ×400)|
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The patient underwent left temporal craniotomy and Simpson Grade 2 excision of the dural tumor. Intra-operatively, the neoplasm was highly vascular, of dural origin with extension into the adjacent temporal bone.
All the tumor bits were processed and five-micron-thick sections were cut from routine formalin-fixed, paraffin-embedded tissue, and stained by hematoxylin and eosin (H and E) stain. Immunohistochemistry (IHC) was performed using streptavidin-biotin immunoperoxidase technique (Envision Kit, M/s Dakopatts, Denmark) using monoclonal antibodies to vimentin, CD68, cytokeratin (CK), glial fibrillary acidic protein (GFAP), S-100 protein and epithelial membrane antigen (EMA), while the proliferation index was evaluated using an MIB-1 antibody (all antibodies were prediluted and obtained from M/s BioGenex, USA).
Microscopic examination of the resected specimen showed multiple bits of reticulin-rich tumor tissue composed of spindled and plump cells arranged in ill-defined storiform patterns and short fascicles. Few bits showed invasion into the bony trabeculae with destruction of the bone. The spindle-shaped tumor cells contained moderate amount of eosinophilic cytoplasm with round to elongated nuclei, few of which showed prominent nucleoli. These cells were intimately admixed with numerous giant cells with abundant eosinophilic cytoplasm and approximately 50-60 small hyperchromatic nuclei. Mitosis was sparse (1-2/hpf), and there was no necrosis. There were no xanthomatous areas in the tumor [Figure 1]b-e.
Immunoreactivity for vimentin in the spindle cells with CD68 in the plump and giant cells confirmed the fibrohistiocytic nature of the tumor [Figure 1]f and g. Absence of GFAP, S-100, EMA and CK-immunopositivity, in conjunction with MIB-1 labeling index (MIB-1LI) of 2% was noted. The lack of pleomorphism and necrosis in the tumor, along with low mitotic activity and MIB-1 LI of 2% confirmed the diagnosis of benign fibrohistiocytic tumor [Figure 1]h.
Patient has been on a regular follow-up. At the last review, she was asymptomatic, ambulant, and with normal speech without any deficit.
| > Discussion|| |
The occurrence of fibrous histiocytic tumors, especially BFH, in the intracranial location is extremely unusual.  BFH has been variably described as fibrous xanthoma and fibroxanthoma. ,,, Many tumors previously reported as fibrous xanthoma were subsequently found to be GFAP-positive and reclassified as pleomorphic xanthoastrocytoma.  Pimental et al., have suggested the term "benign isolated fibrohistiocytic tumors of the central nervous system (CNS)". 
BFH in the central nervous system has been noted to arise either from the brain parenchyma,  the dura, , the cranial bone,  the spine,  or extend intracranially from the skull base  or the pterygopalatine fossa. , In the present case, the tumor had a dural origin and extended into the overlying temporal bone.
Most of the cases reported in the literature affected pediatric cases, less than 24 months of age. ,,,,, The only exceptions were the reports by Ideguchi et al., and Fritz et al., where the age of the patients was 33 years and 45 years, respectively.
The mesenchymal origin of fibrohistiocytic tumors remains controversial. , It has been suggested that these may originate from the perivascular pial sheath or mesenchymal cells, deep blood vessel walls, and primitive mesenchymal cells, which probably explains the intracerebral location in a few of these. Immunohistochemical and histochemical studies have revealed that these neoplasms are positive for vimentin, CD68 and reticulin, while being negative for GFAP and S-100, similar to the index case. ,,,
The benign nature of the tumor was supported by the lack of pleomorphism and necrosis, in conjunction with low mitotic activity and MIB-1LI of 2%, as per the standard accepted criteria. 
On neuroimaging, BFHs are isoattenuated to slightly hypoattenuated on pre-contrast computed tomography (CT) scan and hypometabolic on positron emission tomography (PET)/CT. On T2-weighted image, the tumors are heterogeneously hyperintense to the gray matter, while being isointense on T1-weighted image and homogeneously strongly enhanced on contrast-enhanced T1-weighted image. 
Radical excision of intracranial BFH, provided it is technically feasible, is considered the optimum therapy for a satisfactory outcome. Fritz et al., have, however, suggested the role of adjunctive radiation and chemotherapy in the subsets that invade bone. However, the current case was offered radical excision only. Follow-up results at 12 weeks' postoperatively were satisfactory. Others , have also noted a recurrence-free status during a follow-up period ranging between 15 months and 6 years.
To conclude, this case report documents a rare entity in an intracranial location. Owing to the rarity of BFH, one should be aware of its defining morphological and immunohistochemical characteristics for definitive diagnosis.
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