Case Number : Case 2840- 26 May 2021 Posted By: Dr. Hafeez Diwan

A spindle cell tumour apparently arising in the dermis.  Cells are arranged in fascicles and show nuclear pleomorphism, atypical mitotic activity and a mucinous stroma.

I am thinking along the lines of low-grade fibromyxosarcoma, a myxoid variant of DFSP (less likely) or myxofibrosarcoma (but no curvilinear blood vessels visible).

plexiform spindle cell tumor with atypia

Minimal IHC markers needed

Spindle cell tumour with atypia and mitotic activity. I would consider smooth muscle differentiation on the basis of morphology, likely leiomyosarcoma. Agree IHC needed. Clinical/radiological correlation needed to ascertain if this is primary or metastatic. 

I think the sharply demarcated bundles suggest a primary rather than secondary tumour, but I may be wrong.

Leiomyosarcoma/atypical dermal smooth muscle tumor. 

Atypical dermal smooth muscle tumor.

Leiomyosarcoma (desmin positive)