Diffuse large B‐cell lymphoma (DLBCL) is an aggressive form of non‐Hodgkin lymphoma. Lymphomas involving the female genital system are exceedingly rare, comprising approximately 1% of extranodal lymphomas, with DLBCL being the most prevalent type. Here, we report a rare case of endometrial involvement by DLBCL in a middle‐aged female who presented with abnormal uterine bleeding and fatigue over 3 weeks. Laboratory findings revealed severe anemia, while pelvic ultrasound demonstrated a thickened endometrium, a 1.6‐cm hypoechoic uterine lesion, and multiple enlarged bilateral adnexal lymph nodes. Histological evaluation of an endometrial biopsy revealed diffuse subepithelial proliferation of large, poorly differentiated round cells with finely dispersed chromatin, inconspicuous nucleoli, and moderate cytoplasm. Initial immunohistochemical staining excluded primary epithelial or mesenchymal uterine tumors, showing positivity for CD45. Further workup confirmed CD20 positivity, leading to a diagnosis of DLBCL with a nongerminal center, double‐expressor phenotype. Radiological imaging identified diffuse lymphadenopathy with pulmonary and renal nodules, consistent with Stage IV DLBCL. Given its rarity and morphological overlap, uterine lymphoma may mimic poorly differentiated uterine malignancies, such as dedifferentiated/undifferentiated carcinomas or endometrial stromal sarcomas, especially on small biopsies. Thus, incorporating lymphoma lineage markers is essential for accurate diagnosis. The patient was treated with six cycles of the R‐CHOP regimen, initially achieving a complete metabolic response. However, she was recently admitted for central nervous system (CNS) relapse and restarted chemotherapy.
Amer et al. (Thu,) studied this question.