Uterine leiomyoma with massive lymphocytic infiltration simulating malignant lymphoma. A case report with immunohistochemical study showing that the infiltrating lymphocytes are cytotoxic T cells.

Uterine leiomyoma with massive lymphoid infiltration is very rare and may simulate malignant lymphoma. To the best of our knowledge, this is the first description of such a lesion occurring in an Oriental, and the ninth case in the English literature. A 50-year-old Taiwanese woman had urinary frequency and nocturia because of a uterine myoma. The myomectomy specimen was identified as a well-defined tumor, 6.5-cm in diameter, the cut surface of which was pale, white and whorled. A massive lymphocytic infiltration accompanied by plasma cells and histiocytes was noted in the leiomyoma but not in the surrounding non-neoplastic myometrial fibers. Most infiltrating lymphocytes were positive for CD3 and T cell intracellular antigen-1, a cytotoxic marker. The postoperative course was uneventful, and the urinary symptoms improved within a 6-month follow-up period.