Case Number : Case 883 - 6th November Posted By: Guest

DLCL

DLCL. My preference is for anaplastic large cell lymphoma, based in the excentric horse-shoe nuclei in some large cells.

DLBCL with mosaic stone- like arrangement of neoplastic cells prominent in figure 2, however, IHC is mandatory to exclude other large cell lymphomas as it will affect the management of the patient.

Cutaneous lymphomas are very challenging.
Based on the very atypical cells and as a isolated clinical lesion, I would sugest 2 principal differential diagnosis: DLBCL, maybe leg-type, and PCALCL. I prefer this last one because of the very atypical cells, the isolated knee lesion and the kidney-shaped nuclei present in many cells.
The picture 3 shows a perivascular arrangement that woul make us speculate about the diagnosis of Extranasal NK/T cell lymphoma, but these lesions are very agressive, rare, admixed with necrosis and I really don´t see angioinvasion. EBV-hybridization would be important. If positive, but in the setting of a B cell lymphoma, I would think about EBV-positive DLBCL of the eldery.
Immunohistochemistry is essential for this case and, depending on the results, EBV-hibridization and T-cell receptor study.

Primary cutaneous diffuse large B-cell lymphoma, leg type

Primary cutaneous diffuse large B-cell lymphoma, leg type. Pleomorphic large lymphocytes predominate and there are some angiotropic foci. Immunohistochemistry is required.

DLBCL leg type versus ALCL. Favor the first one, but IHC mandatory. Also, testing for EBV would be indicated.

Agree with the above DDx.... Nice case :-)

Agree with above differential diagnosis.
I would favour Primary cutaneous diffuse large B-cell lymphoma, leg type

This is large B-cell lymphoma, leg type. MUM-1 and Bcl-2 were positive (in addition to CD20)