OBJECTIVETo investigate magnetic resonance imaging (MRI) findings of the atypical leiomyoma in the female reproductive system in comparison with the pathological features of the neoplasms.

METHODSA retrospective analysis of the MRI findings and the pathological features was conducted in 24 cases of atypical leiomyoma involving the female reproductive system.

RESULTSAtypical leiomyomas were displayed by MRI as solid tumor mass surrounded by cystic degeneration, pseudotumors, or solid mass with homogeneous signal intensity. Intrauterine lesions were found in 19 cases, involving the subserosal layer (n=11), intramural region (n=4), broad ligament (n=3), cervix (n=2), submucous layer (n=2), vagina (n=1), and the ovary (n=1). Except for two cases with submucous lesions shown as solid mass, all the cases had lesions appearing as solid cystic mass, whose solid part showed hypo or isointense signals on T1WI and moderate hyperintense signals on T2WI, with heterogeneous enhancement after contrast agent injection. Tumor cell and interstitial cell swelling, vascular hyalinosis, hyalinosis, myxoedema, cystic degeneration, and hemorrhage were found in the lesions.

CONCLUSIONLeiomyoma can occur at almost any site in the female reproductive system, and atypical leiomyoma usually are shown as solid cystic mixed mass in the pelvic cavity. Evaluation of the relationship between the solid mass and cystic portion and observation for the presence of low signal on T2WI may help in the diagnosis of atypical leiomyoma.