Track

Case Reports

Abstract

Diffuse large B-cell lymphoma (DLBCL) is the most common and an aggressive subtype of non-Hodgkin lymphoma. The risk of developing DLBCL increases in patients with other lymphomas, such as mycosis fungoides (MF). In this report, we present an 81-year-old female with early-stage MF who simultaneously progressed to tumor stage, large-cell transformed (LCT) MF, and developed a primary DLBCL in a lymph node (LN). She presented with a tumor on her leg and new lymphadenopathy in her right axilla. Skin biopsy of the tumor revealed infiltration of large atypical CD3+, CD4+, and CD30+ cells and a smaller portion of CD8+ cells in the dermis, consistent with LCT MF. A biopsy of the axillary LN revealed diffuse sheets of CD20+, BCL-2+, c-MYC+, and CD10- cells, which highly suggest double expressor DLBCL. High-throughput sequencing revealed monoclonal T-cells in the skin tumor and a monoclonal B-cell population in the LN. The above findings led to simultaneous diagnoses of LCT MF and nodal double expressor DLBCL. Since the patient had two distinct histological subtypes in two unique anatomic locations, it was classified as a discordant coexisting lymphoma. Had these biopsies not been taken and had the new lymphadenopathy been assumed to be a progression of MF into the tumor stage, her treatment and prognosis would have been dramatically altered. Our case uniquely demonstrates the importance of performing a full pathological workup in MF patients presenting with new lymphadenopathy.