Coexistence of large cell transformed mycosis fungoides and diffuse large B‐cell lymphoma in one patient

Abstract

AbstractDiffuse large B‐cell lymphoma (DLBCL) is the most common and aggressive subtype of non‐Hodgkin lymphoma. The overall risk of developing DLBCL is increased 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. Biopsy of the axillary LN revealed diffuse sheets of CD20+, BCL‐2+, c‐MYC+, and CD10− cells, highly suggestive of 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. Our case demonstrates the importance of performing a full pathological workup in cutaneous T‐cell lymphoma patients presenting with lymphadenopathy.