A study of four cases of extra-orbital giant cell angiofibroma with documentation of some unusual features

Aims: To document the clinical, light microscopic, immunohistochemical and ultrastructural features of four cases of extra-orbital giant cell angiofib romas. Methods and results: Sections of formalin-fixed paraffin-embedded specimens were studied by haematoxylin and eosin, reticulin and immunohistochemical stains. Electron microscopy was carried out in two cases on tissue fixed in formalin. The age of the patients ranged from 30 to 41 years. Two patients presented with a soft tissue swelling in the left groin. one patient had a left axillary soft tissue lump and one patient presented with a parotid lu mp. All lesions were well circumscribed and contained variably cellular and vascularized tissue composed of round to spindle cells with a patternless arrangement. scattered multinucleate giant cells and pseudovascular spaces conforming to the description of giant cell angiofibroma. Mononuclear and m ultinucleate tumour cells were both positive for vimentin and CD34: one tum our exhibited focal S100 protein and GFAP positivity. Both of the tumours e xamined by electron microscopy showed fibroblastic features. but in additio n one contained cells having Schwannian features. All four patients were we ll without recurrent disease on follow-up (average 25 months). Conclusion: Giant cell angiofibroma shares many features with solitary fibr ous tumour and giant cell fibroblastoma and shows a wider distribution than initially recognized. Rarely, Schwannian differentiation may be observed i n these tumours.