Uterine leiomyomas with eosinophils: A clinicopathologic study of 3 cases

Although leiomyomas (LMs) of the uterus are common, hematopoietic component s within these tumors are not. Lymphoid and other hematopoietic elements ha ve been previously recognized, but eosinophilic infiltrates in LMs have rec eived little attention in the literature. The clinical and pathologic featu res of 3 cases of uterine LM with eosinophilic infiltration were studied. T he patients ranged in age from 35 to 62 years and presented with abdominal and/or pelvic pain and abnormal uterine bleeding. None had peripheral blood eosinophilia or clinical evidence of allergy or parasitic infection. One p atient had a benign LM, and the other 2 patients had smooth muscle tumors o f uncertain malignant potential. The tumors contained variable numbers of e osinophils and Giemsa stains showed variable numbers of mast cells in addit ion to the eosinophils. We also performed immunohistochemical and in situ h ybridization studies to assess for interleukin-5 (IL-5) and eotaxin in thes e LMs. There was no consistent association between the presence of eosinoph ils and either IL-5 or eotaxin in smooth muscle cells, suggesting that mech anisms other than IL-5 or eotaxin production may account for the eosinophil ia. Because eosinophils are believed to be involved in wound healing, tissu e remodeling, and fibrosis, their presence within LMs may reflect a respons e to tissue injury produced by the neoplasm rather than intrinsic recruitme nt by chemotactic factors produced by the smooth muscle cells. Their presen ce, however, does not appear to have any clinical significance.