Case Number : Case 3036 - 24 February 2022 Posted By: Saleem Taibjee

Lupus profundus vs SPTCL, favor the prior based on morphology, would be helpful to see T cell markers.

Lupus panniculitis is good spot. However I’m having trouble to find the true hyalinizing fatty change. There are plasma cells, and these fit well lupus diagnosis. But lymphoid cells are a bit atypical. CD20? Lymphomatoid granulomatosis?

I think both lupus profundus and sub-cutaneous panniculitic T-cell lymphoma are unlikely diagnoses in an 11 year old boy.  We would need to consider other possibilities such as alpha-1 anti-trypsin deficiency, cold panniculitis or post-steroid panniculitis.

Lupus profundus and SPTCL have overlapping histopathological features. In this one would favour lupus profundus based on hyalinization and plasma cells. But IHC will add in making a distinction form SPTCL. 

Lupus profundus is the most likely, not to forget morphea profunda.

Thanks. Interesting discussion.

Yes, I favoured lupus panniculitis. Definitely more lobular than septal (which Luis Requena suggests we try to commit to), hence morphoea is less likely. I too was nervous about the density of the infiltrate, and knowing about those cases with overlap/evolution to subcutaneous panniculitis-like T-cell lymphoma which are well-described. To this end, the immunohistochemistry is somewhat reassuring in so far as confirming a mixed infiltrate with a predominance of CD4 over CD8. And actually there is not really convincing 'rimming' in this case - more of a 'pseudo-rimming'. I looked hard for hyaline change within the fat, and have already shown the possible small foci in the histology above. But certainly it was not dramatic in this case, perhaps reflecting the stage of evolution of the area biopsied.

Some of the immunos are shown below. The density of the B-cell component was a little bit alarming in this case, and I note Vincenzo's differential of lymphomatoid granulomatosis. However EBER is negative (not 100% excluding). There was no evidence of restriction on Kappa vs Lambda. No doubt, this case will require clinicopathological correlation and clinical follow-up.

BW

Saleem