Although
leiomyomas (LMs) of the uterus are common, hematopoietic components within these
tumors are not. Lymphoid and other hematopoietic elements have been previously recognized, but eosinophilic infiltrates in LMs have received little attention in the literature. The clinical and pathologic features of 3 cases of uterine LM with eosinophilic infiltration were studied. The 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 patient had a benign LM, and the other 2 patients had
smooth muscle tumors of uncertain malignant potential. The
tumors contained variable numbers of eosinophils and Giemsa stains showed variable numbers of mast cells in addition to the eosinophils. We also performed immunohistochemical and in situ hybridization studies to assess for
interleukin-5 (IL-5) and eotaxin in these LMs. There was no consistent association between the presence of eosinophils and either
IL-5 or eotaxin in smooth muscle cells, suggesting that mechanisms other than
IL-5 or eotaxin production may account for the
eosinophilia. Because eosinophils are believed to be involved in wound healing, tissue remodeling, and
fibrosis, their presence within LMs may reflect a response to tissue injury produced by the
neoplasm rather than intrinsic recruitment by
chemotactic factors produced by the smooth muscle cells. Their presence, however, does not appear to have any clinical significance.