Uterine leiomyoma with massive lymphoid infiltration: case report and review of the literature.

Uterine leiomyoma with massive lymphoid infiltration is a rare and unusual pathological finding. Only 13 cases have been reported in English literature. A case of uterine leiomyoma showing massive lymphoid infiltration in a 45-year-old woman is described. The tumor was relatively soft compared with usual leiomyomas. Microscopically, the tumor showed the typical features of leiomyoma with moderate to severe lymphocytic infiltrate consisting of mature lymphocytes, a few plasma cells and occasional histiocytes. This cellular infiltration was confined to the leiomyoma. Immunohistochemically, the diffusely infiltrated lymphoid cells were stained by antibodies to CD45RO, CD3 and CD8. Germinal centers were stained by antibodies to CD20 and CD79a. Some CD68+ histiocytes were seen. Lymphoid infiltration within the leiomyoma is a peculiar histological morphology, although the cause is not clear. The recognition of its distinct histological features is important to avoid possible confusion with differential diagnoses including malignant lymphoma, inflammatory pseudotumor and pyomyoma.