Introduction: Ovarian lymphoma is rare and often misdiagnosed, as its clinical presentation can be similar to other more frequent tumors. It accounts for <1% of all non-Hodgkin lymphomas, with high-grade B-cell lymphoma being the most frequently implicated subtype. Case Description: A 48-year-old woman presented with bilateral ovarian masses, elevated CA-125, and extensive abdominal and thoracic lymphadenopathy. She was managed as advanced ovarian cancer and underwent TAHBSO. Grossly, both ovaries were enlarged and nodular. Histology showed a round cell neoplasm composed predominantly of medium-sized, cleaved lymphocytes, admixed with scattered larger atypical cells. Initial immunohistochemistry panel demonstrated diffuse CD45 positivity and negativity for AE1/AE3, Inhibin, SALL4, Desmin, and Calretinin. Subsequently, CD20 and PAX5 showed diffuse reactivity. CD10, BCL2, and BCL6 highlighted neoplastic follicles. CD3 was negative. High-grade B-cell lymphoma was considered; however, the Ki-67 proliferative index was 38%, and c-MYC expression was low (5%). A final diagnosis of follicular lymphoma involving both ovaries was rendered. Discussion: The clinical presentation strongly suggested advanced ovarian carcinoma. However, histologic and immunophenotypic evaluation established lymphoma. Although aggressive subtypes are more common in advanced cases, indolent entities such as follicular lymphoma should also be considered, particularly in resource-limited settings where delays in diagnosis occur. Distinguishing lymphoma from carcinoma is critical, as management differs significantly and misclassification may lead to overtreatment. Conclusion Recognition of ovarian lymphoma is critical, as accurate diagnosis alters management and prevents unnecessary radical surgery.
CA-125 Antigen ; Immunohistochemistry ; Lymphoma, Follicular ; Ovarian Neoplasms