Case Number : Case 1764 - 2 March - Dr Arti Bakshi Posted By: Guest

Thursdays wouldn't be the same without the latest Spot Diagnosis Case from Dr Arti Bakshi.

Geoff Cross - DermpathPRO Projects

The solar damaged skin, sclerosing deep dermis and lymphoid nodular peripheral reaction could make think of a desmoplastic melanoma, but silhouette looks like symmetrical and there isn't too much nuclear atypia...so Desmoplastic Neurotized Nevus is my first thought. 

Concerning for desmplastic melanoma but not marked atypical. I would do S100 to confirm and SMA to rule out smooth muscle neoplasm, and ki67.  Depending on clinical and results of IHC, would go from there.

I have the same thoughts, desmoplastic nevus, less likely desmoplstic melanoma

Exercising the spot diagnosis, I favor desmoplastic melanoma. Site, assumed old age of the patient (taking into account the solar elastosis evidenced on low power view), impaired maturation, some nuclear pleomorphism, and lymphoplasmacytic aggregates are the findings that formed my opinion. Lesion was incompletely excised, so other characteristics cannot be accessed, including size, circumscription, neurotropism, and deep infiltration.

I also thought of desmoplastic melanoma

I agree desmoplastic nevus x desmoplastic melanoma.

Scar -like dermal proliferation with random atypia, scattered lymphoid aggregates and plasma cells. I think this is a desmoplastic melanoma.

Desmoplastic Melanoma.

This is an incisional bx from a 1cm lesion on the scalp of a 80 year old man. S100 was diffusely positive and Melan A was negative. Agree that atypia is subtle, but given the clinical context, went for a Desmoplastic Melanoma too.