Histopathology report
MICROSCOPY: Sections show a large dermal and deep subcutaneous tissue tumour comprising the proliferation of spindle cells arranged in a fascicular and vague storiform pattern. These neoplastic tumour cells infiltrate the fat lobules forming a honeycomb pattern. The tumour is relatively well circumscribed; however areas with infiltrative tongues at tumour front are also noted infiltrating surrounding adipose tissue. The tumour is reaching and involving skeletal muscle focally. Grenz zone is also noted between the tumour and epidermis with ulceration of the epidermis. In addition, the tumour appears highly cellular with areas of prominent herringbone fascicular growth pattern and frequent mitotic figures (up to 17-18 per 10 HFP) which support the transformation into a more aggressive tumor (i.e. fibrosarcoma). No tumour necrosis is seen.
The neoplastic spindle cells are positive for CD34 while being negative for CK, MNF, Factor XIIIa and CD10.
Resection margins are all negative. Tumor is close to deep resection margins at areas (within 1mm).
COMMENT: The features of hypercellular spindle cell tumour with herringbone fascicular growth pattern and frequent mitotic figures are in keeping with fibrosarcomatous transformation/progression within DFSP.