Activated B-cell signet ring lymphoma: A case report and a comparative review of the literature

Signet ring cell lymphoma is an exceedingly rare subtype of non-Hodgkin lymphoma that was originally thought to be a morphologic variant of follicular lymphoma. To date, 56 cases have been reported, with the majority occurring in lymph nodes and bone marrow. Herein, we report a case of a 37-year-old female who presented with a left inguinal mass and high suspicion of lymphoma that was rendered on MRI. A successful ultrasound-guided core biopsy was performed. Pathologic examination revealed a diffuse large B-cell lymphoma (DLBCL) with unique signet ring histology and post-germinal center phenotype. In-situ hybridization showed an isolated BCL-6 gene rearrangement and confirmed the absence of a double-hit phenotype. This case would be situated as the second case of activated B-cell (ABC) signet ring lymphoma and the first case to arise in this anatomic location. The patient recently initiated therapy with a standard six-cycle regimen of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone).