Case Number : Case 1581 - 18 July Posted By: Guest

Cutaneous infiltration by lymphomatous cells. My first hypothesis is PCDLBCL-leg type. Waiting the immunostains.

Yes, DLBCL-leg type.

The immunostais show positive result for CD20, BCL-2, BCL-6 and MUM-1, confirming the impression of PCDLBCL leg-tyoe.

Just to add to the discussion. PCFCCL can have a predominance of large cells (usually with centroblast morphology) and therefore come to the differential diagnosis. However, the topography is not the typical one for PCFCCL and the strong expression of BCL-2 and MUM-1 altogether with this predominance of large cells favour primary cutaneous large b-cell lymphoma (leg type) over the latter. 

Also just to add, when the PCFCCL appears in the legs it carries a worse prognosis.

Yes we reported it as favouring DLBCL, in keeping with primary cutaneous, leg-type but of course pending staging and CPC.  Agree with discussion. Presume the population of small cells are mainly T-'s.  Robson et al recently reported on p16 (I think) in DDx of PCDLBCL, leg-type from FCCL (but I cannot now locate the reference!). Incidentally EBER was negative.  Ki67 was moderate ~50%.

Rick, it is p63 that they used http://www.ncbi.nlm.nih.gov/pubmed/26332336 I have not read this one yet but looks interesting