Unusual benign neurogenic soft tissue tumour. Epithelioid schwannoma or an ossifying fibromyxoid tumour?

An unusual form of subcutaneous soft tissue tumour with benign character is reported. The tumour was composed of uniform cells which were epithelioid in appearance. True myxoid matrix, osteoid formation or metaplastic bone were not present. Immunohistochemically S-100 protein and vimentin was demonstrated in the tumour cells. Electron microscopic examinations showed fragmented or continuous basal lamina, interdigitating cytoplasmic projections, myelin-like figures and a few cell junctions. The immunohistochemical and electron microscopic results indicate that the tumour is of Schwann's cell origin. Based on light microscopic, electron microscopic and immunohistochemical results we think our case is an epithelioid benign schwannoma but the non-ossifying form of fibromyxoid tumour of the soft parts cannot be excluded with confidence.