Abstract

The most common type of non-Hodgkin lymphoma, DLBCL is an aggressive disease. Most patients present with rapidly enlarging lymph nodes or tumor masses at extranodal sites. Approximately 30% of DLBCLs present with extranodal disease, with the most common primary extranodal sites being the gastrointestinal tract and Waldeyer’s ring, although any organ may be involved. Here we describe the case of a 61-year-old female with history of seizures, diabetes, depression, and hepatitis C infection who presented with an ulcerated groin plaque, fatigue, and 90 lbs weight loss. A shave biopsy showed a diffuse dermal infiltrate composed of large lymphoid cells with pleomorphic nuclei, prominent nucleoli, amphophilic cytoplasm, and numerous mitotic figures. Immunohistochemical analysis showed a predominant large B-cell population that was positive for CD5, BCL-2, BCL-6, MUM-1, C-Myc, and LEF-1 and negative for CD10, BCL-1, Sox-11, and CD30. A high proliferative rate (95%) was illustrated by Ki-67. Next generation sequencing studies revealed MYD88 mutation and fluorescence in situ hybridization studies were negative for MYC, BCL2, and BCL6. With a preliminary diagnosis of primary cutaneous DLBCL, positron emission tomography (PET) scan was conducted that showed intense uptake in the groin lymph nodes and multifocal femur uptake concerning for osseous marrow involvement.  Accordingly, a diagnosis of systemic DLBCL was made.  The findings of CD5 positivity, dual expression of BCL-2 and C-Myc, and markedly elevated Ki-67 proliferative index are associated with a worse clinical outcome.  The cutaneous presentation and requirement of interdisciplinary collaboration highlight the importance of clinicopathologic correlation for accurate diagnosis.