Case Number : Case 2024 - 08 March 2018 Posted By: Iskander H. Chaudhry

Superficial and deep dense lymphocytic infiltrate with a few eosinophils. Persistent insect bite reaction or lymphocytoma cutis. Silver stain to detect borrelia may be tried. Nodular scabies will appear similar but won't be seen on the face.

Always challenging cases. Frank ulceration is not seen. In this instance nodular B-cell pattern (mixed cells) but also quite prominent epidermotropism & Pautrier-like microabscesses.  Can't see granulomatous features that might suggest Leishmaniasis. Given the eosinophils a persistent arthropod reaction (pseudolymphoma) is a good possibility. I'd probably run a Kappa and Lambda and a limited B-cell panel. Think I'd also like to see the clinical images and suggest MDM discussion is an clinical concerns.

I agree with Dr. Carr, but am less worried about a B cell lymphoma; the presence of epidermal involvement and the clinical are reassuring. The thing about true cutaneous lymphomas is that the really horrible ones never go away. Over treatment is usually more of a problem than under treatment. Pseudolymphoma/insect bite reaction is my diagnosis. Pretty impressive, though.

My first hypothesis is also pseudolymphoma. I think I would have performed a small panel of immunos like Richard remarked

"Real" pathologists don't like the terms 'pseudolymphoma' and 'lymphocutoma cutis' that are used by dermatologists. (Ref Ronald Rapini's book).They use the term 'reactive lymphoid hyperplasia' instead. What do the "real" pathologist in this forum say ?:--))

Favour a "Reactive lymphoid Hyperplasia", insect-byte induced.

Dr Chaudhry's comment:

The final diagnosis was Pseudolymphoma likely secondary to insect bite; MDT discussion. 

I'm a surreal histopathologist and probably a bit lazy at times with my terminology.  Happy to be corrected though!