Case Number : Case 2694 - 03 November 2020 Posted By: Iskander H. Chaudhry

These sections show a dense, sheeted, predominantly lymphocytic infiltrate occupying the upper dermis.  The infiltrate also includes histiocytes, plasmacytoid cells and a few rather superficially located neutrophils .  There is only trivial lymphocytic epidermal exocytosis and lymphocyte cytology is not obviously atypical.  There is a minor degree of basal vacuolation.

Immunohistochemistry is essential to determine whether this is a lymphomatous, or pseudolymphomatous process.

agreed to above description

Case updated with Immunohistochemistry stains.

First spot: Benign Lichenoid Keratosis. 

My first thought was similar to Vincenzo's but I thought there was basal keratinocyte atypia so I thought it could be inflamed actinic keratosis. However I think keratinocyte atypia can also be seen in lupus. I don't know for sure. Mucin in the deep dermis? 

Iskander - may we have your thoughts on this one please?

Dear All. My comments below:

Skin with acute on chronically inflamed lesion with acanthosis and dense dermal inflammation. No
junctional nesting is seen. The lesion is negative for Melan A and scattered CD68 cells are seen in the dermis. The epidermis focally shows mild reactive atypia, however, the main feature is the intense dermal inflammation with possible lymphoid aggregates. Immunochemistry shows a mixed T and B cell infiltrate (lymphoid aggregate)  with surrounding T cell infiltrate (CD4>CD8). CD30 was negative. On clinical discussion the appearances were most in keeping with a pseudo-lymphoma.