Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg-Type
Lessons From The Friday Unknowns
The patient has a 3-month history of nodules on the left ankle and the current nodule sampled was described as a violaceous.
Histologic sections of show extensive involvement of the dermis by lymphoma.
The neoplasm has a diffuse pattern and is composed of an almost uniform population of large cells with central prominent nucleoli suggestive of immunoblasts.
The neoplastic cells are positive for CD5, CD20, BCL–2, BCL–6 (weak), MUM11/IRF4 and PAX5, and are negative for CD3, CD10, CD21, CD23, CD43, cyclin D1, kappa and lambda. MYC stain is negative. The antibody specific for Ki-67 shows a very high proliferation rate of 90–95%.
The neoplastic cells are negative for Epstein-Barr virus encoded RNA (EBER).
FISH studies showed BCL6 rearrangement but no evidence of MYC rearrangement or IGH/BCL2.
Link to digital slides slides: https://bit.ly/2YQqaNJ | Slides labeled case 5