Case Number : Case 2394 - 3 September 2019 Posted By: Uma Sundram

Follicle centre cell B cell lymphoma 

Nodular aggregates of epitheliod cells near to re-excision site makes me think in Melanoma.

Something resembling juvenile xantogranuloma or solitary RCH or RDD ( but I don't like thinking of RDD without plasma cells ).

Poorly differentiated proliferation, needs correlation with previous biopsy. IHQ can be of great help if no more clinical information is provided.

I was trying to trick you guys. Dr Alex has it right. This was a re excision of a melanoma. I knew it was a melanoma re excision but did not have access to the prior. The large cells made me initially think of biopsy site changes, and I did a SOX 10 just in case. All of the large cells with abundant cytoplasm were both MART1 and SOX10 positive. On low power it looks like scar envelopes the infiltrate which is very lymphocyte rich and circumscribed. So, always stain if in doubt! I'm glad I did in this case.

Very educative case, Uma. Thanks!!!