A 40-year man presented with a progressively enlarging painless mass in the antero-medial aspect of the right leg for 1 year with no previous history of trauma. On local examination, the mass measured 10×8×4 cm, with no tenderness, freely mobile with no fixity to underlying structures and the overlying skin normal. A MRI revealed a well-defined soft tissue lobulated mass lesion with central areas of necrosis suggestive of a soft tissue tumour ().
Figure 1 MRI and gross findings of the solitary fibrous tumour involving the right leg. (A, B) MRI showing a well-defined soft tissue mass, with no involvement of underlying structures and bone, on the antero-medial aspect of right leg. (C) Cut section of the (more ...)
The mass was resected along with a 1 cm margin and subjected for histopathological examination.
Grossly, the specimen received was well-circumscribed, nodular, pale yellow in colour and measured 8.5×5.5×4.5 cm. On cut sections, the appearance was whitish with focal areas of central haemorrhage ().
Microscopically, the tumour was well-circumscribed with both hypocellular and hypercellular areas, which at places were separated by keloid-type collagen deposition. Random arrangement of cells was seen in most areas. Areas with thick walled hyalinised blood vessels and haemogipericytoma like pattern were observed. Cells were spindly in most areas along with focal myxoid change, necrosis and haemorrhage. Mitotic count was 5 per high power field (HPF) (magnification×400). Immunohistochemically, the tumour was strongly positive for CD34 along with focal positivity for CD99 and BCL2. The microscopic features are presented in .
Figure 2 Photomicrographs of solitary fibrous tumour with atypical features. (A) Hyalinised blood vessels with haemangipericytoma-like arrangement of spindle cells (H&E×40). (B) Keloid-like thick bands of collagen traversing the tumour (H&E (more ...)
The above findings were helpful for a final diagnosis of solitary fibrous tumour of the soft tissue of the right leg.