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Case Number : Case 2581 - 28 May 2020 Posted By: Saleem Taibjee

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73M. Punch biopsy upper arm, asymptomatic rash on right upper arm, shoulder, chest wall > 4 years ? Granuloma annulare

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Saman Fatah

Posted (edited)

Clinically there are erythematous to slightly violaceous dermal arcuate and annular plaques with a striking well defined border on his back.

Some of the interstitial cells are large with an irregular outline.

I wonder whether it is worth considering further IHC to clarify the nature of those cell especially if lymphoid or not? The appearance of the rash is not consistent with GA commonly seen.

Edited by Saman Fatah
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Josie Bisi


An IHC would be prudent to define the clonality of interstitial cells, they appear to be lymphoid, with large nuclei. I think of some type of lymphoma / leukemia infiltrating the skin.

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Anil Patki


Deep variety of erythema annulare centrifugum.


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Saleem Taibjee


This was a rather intriguing case which I encountered in routine digital sign out. I nearly fell into the trap of concurring with clinician and opting for GA (interstitial variant) because it is a remarkably good mimick at low/medium power. But fortunately I dwelt for a moment on the cytology, and noted that the interstitial cells appeared to have large nuclei, and were not right for histiocytes.

A few of the stains are shown below, but in summary, the staining of the intersitial cells:

Positive: CD20, CD79a, Bcl-2, Bcl-6, MUM-1, High Ki67
Negative: CD3 (perivascular reactive cells only), CD5, CD10, CD43, EBER
Kappa/Lambda: Possible restriction, but sparse plasma cells only so difficult to assess.
Additional investigations (all negative/unremakable): Borrelia, syphilis, hepatitis B & C serology, Full blood count, blood film, LDH, Staging CT scan
My conclusion:
Interstitial variant of B-cell lymphoma mimicking interstitial granulomatous dermatitis (e.g. GA)
The large cells, high Ki67 and MUM1 would suggest a Diffuse large B-cell lymphoma and potentially aggressive behaviour

BUT ….

The patient has remained well for 6 years, with only very slow evolution of the rash.

Dr Alistair Robson and others have also provided second opinions on this case, and alerted me to a small series reported by Massone et al (Atypical clinicopathologic presentation of primary cutaneous diffuse large B-cell lymphoma, leg type) in which indolent clinical behaviour was described. But this does seem to be a rather unique case.

30985 CD20_10.0x labelled.jpg

30985 CD3_10.0x labelled.jpg

30985_Ki67 20.0x labelled.jpg


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Dr. Mona Abdel-Halim


Very interesting case! Thanks Saleem for sharing!

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