Case Number : Case 2161 - 20 September 2018 Posted By: Iskander H. Chaudhry

Mycosis fungoides.

It is a difficult case.

It is not common to see MF along with so many lymphocites, unless the case is a folliculotropic MF or a late-stage (usually tumoral) MF. But the clinical hypothesis is eczema. It doesn´t fit. The deep infitrate also is not common for MF. There is a lot of CD20 positive lymphocites, eos and plasma cells along with CD30-positive cells that are not anaplastic. I am not sure yet, but I thisk this may be a pseudolymphoma case like a lymphomatoid drug reaction. Waiting for more comments and the final diagnosis.

Differential diagnosis with folliculotropic MF

somewhat a green zone is seen focally

numerous Eos are seen in the infiltrate mixed with lymphocytes and plasma cells. there is peri follicular inflammation

It is not MF for sure

could be a reaction pattern to a drug/irritant/bug bite

Persistent insect bite reaction/nodular scabies

CD4+ intraepidermal cells are more in keeping with MF. 

Clinical correlation is essential here.  What is distribution of lesions, duration, and response to treatment, if any.  Are they persistent or do they regress and recur?  I would request a photo if available and discuss case with clinician. The positive CD30 pattern could be seen in lymphamatoid papulosis.  My first priority is to rule out follicular MF, and also consider follicular mucinosis (although infiltrate is denser than I usually see and not most common site) or a pseudolymphoma (drug or bite induced).  Nodular  scabies should be considered depending on clinical correlation and/or the results of above studies.

Good discussion and excellent points & suggestions. Obviously history is going to be quite important.

My gut feeling is it is lymphoma (atypical dermal cells), CD4 positive, and in view of the B-cells & eosinophils & plasma cells would add a consideration of angioimmunoblastic T-cell lymphoma (I've seen epidermtropic cases - not follicular mucin though). I certainly considered like colleagues post treatment scabietic nodules, other pseudolymphomas and MF

Many thanks everyone - the case was followed up and lymphoma excluded based on clinical and mix T an B cell infiltrate. The rash was classed as a pseudo-lymphoma and resolved over time!