Case Number : Case 2146 - 30 August 2018 Posted By: Raul Perret

? Acral myxoinflammatory fibroblastic sarcoma. 

Shwanoma with ancient changes

My another thought is PHAT

I'm thinking of a myoepithelioma. My second thought is a melanocytic nevus, myxoid variant.

Myxoid variant is sometimes found in melanoma, rarely in nevus.

Sox10 is usually expressed in melanocytic lesions, but, often,  in cutaneous myoepitheliomas too.

So myoepithelioma remains my first choice.

These are the rest of immunos: (AE1/AE3): neg,
CD34 : neg, smooth muscle actin: neg, desmin : neg, SMARCB1 (INI1): positive (conserved), Ki67 : 3 %. Final diagnosis was epithelioid schwannoma with focal atypia (ref: https://www.ncbi.nlm.nih.gov/m/pubmed/26752543/). Myoepithelioma and spitz nevi are good differentials but hyalinized blood vessels and a thick capsule (as seen in this case) are not typical of those entities.