Case Number : Case 901 - 2nd December Posted By: Guest

Recurrent malignant melanoma is my favorite here however others need to be excluded by IHC.

Friday's case was a metastasis from the colon (CDX2, CEA positive). Apologies for delay, long day in Paris!

I also think it is a recurrent Melanoma. If there is no history, immunohistochemistry is mandatory.

melanoma

Agree with recurrent melanoma

Agree with recurrent melanoma

Pleomorphic recurrence of melanoma or squamous cell carcinoma.

I favor a high-grade squamous carcinoma. There is high-grade atypia at the junction, most pronounced / best seen in the first low-power image (right edge). Given the epidermal atypia, and clinical history, there is consideration that this tumor is an 'import' from the flap, and not original to the nose.

To add to the above differential of SCC vs. melanoma, less likely would be:
1. Epithelioid angiosarcoma ( given other images, it seems that the red cells in last photo are most likely artefactual to procedure, but some appear placed within intracellular lumens. )
2. High grade sebaceous carcinoma (the vacuolar clear-cell changes seem more consistent with that commonly seen in poorly differentiated SCC / Bowen's disease).

I also thought of recurrent sebaceous carcinoma, but the vague nested nature of the tumor masses made me favor melanoma. I have realized the atypia of the basal layer but explained it by actinic keratosis in the flap, the tumor masses did not look like squamous cell carcinoma to me, but it is of course a possibility... I still feel it is a recurrence of the original tumor.. Lovely case...

Don't forget metastasis (from a systemic primary) is also a possibility. What looks like nesting pattern may be intra-vascular tumour. Certainly some endothelial looking cells noted around some nests. Agree should consider all of the above (including angiosarcoma).

Favor recurrent sebaceous carcinoma with a DD of melanoma.

Merkel cell carcinoma (neuroendocrine carcinoma).

MCC :-))