Case Number : Case 1930 - 23 Oct - Dr Limin Yu Posted By: Guest

I think this is a DERMATOFIBROSSARCOMA PROTUBERANS.

Thomas Paulo MD

Natal RN, Brazil

Reactive! Fibromatosis-like hypertrophic scar ( ?secundary to inflamed branchial cyst)

I am not getting the lay of the land here. Is that normal epidermis or cyst?

Dermal process is banal and myofibroblastic in high power images, so I favor scar (with retraction of the overlying epidermis). If that doesn't fit clinically, other considerations are fibromatosis and hemorrhagic dermatomyofibroma. In a younger person with a rapidly growing nodule, I would favor nodular fasciitis. If suspected in this case, USP6 FISH should be considered.

LGFMS (alternating myxoid and fibrous areas) and myxofibrosarcoma (myxoid stroma and curvilinear vessels) are unlikely from these images. DFSP and KS should cross mind, but myofibroblasts here look solid.

Nodular fasciitis?

This is a deep fibromatosis (desmoid tumor).  beta-catenin shows nuclear positivity. 

All the discussions are insightful and I highly appreciated them!