Case Number : Case 1631 - 26 September Posted By: Guest

Today we have a special 'extra' case from Dr Richard Carr, there will be extra images posted at 6pm UK time to aid your diagnosis.

Cheers, Geoff

Give me 5 minutes and I will replace case and matching images

Cheers, Geoff

Done, new case images uploaded.

Cheers, Geoff

Dermal based nodular lymphoid proliferation with tropism for adnexae. The follicle highlighted doesnt show tingible body macrophages or zonation, there are some atypical cells present, some of larger size. There are some plasma cells too. Favour b cell lymphoma, immunohistochemistry is a must (cd20, cd3, cd10, bcl-2, bcl-6, cd138, kappa, lambda, ki67) but the morphology makes favour FCL over MZL for correlation with the clinical setting.

Medium sized centrocytoid cells are found beyond the germinal centre boundaries, a clue to a primary cutaneous FCL, so agree with Raul comment. But I'm finding this case particularly difficult to differentiate by a MZL and, above all, by a benign lymphoid hyperplasia. Peripheral plasma cells are few, so could be difficult k/lambda restriction interpretation...The last two fig make me favour a follicular lymphoma.

Light c.r.  fit more with MZL but, may be I'm wrong, for me CD21 doesn't show a colonized follicular center, instead an early low grade FCL with plasmocytic differentiation. What do you think about?

funny things in this case is that the plasma cells seem to be lambda restricted and cd21 highlights irregularly shaped follicles. I would still perform the rest of the immunos as you guys mentioned and still favour FCL.

Good discussion. I interpreted these as reactive GCs (I'm guessing therefore Ki67 was very high, Bcl2 negative, sorry did not photograph). I thought the peripheral plasma cells and immature plasmacytoid cells & monotcytoid cells in the superficial dermis showing light chain restriction was quite typical of marginal zone lymphoma in this case but of course supported by Lambda light chain restriction. PCR showed weak clonal bands in a polyclonal background - I did not think this altered the interpretation of a likely marginal zone lymphoma in this case.

Agree - the NHS is still in the dark ages though!