IS Case 154: Benign metastasizing leiomyomas to the lung
Imaging Sciences URMC 2008
Publication Date: 2009-05-21
Benign metastasizing leiomyomas to the lung
The patient underwent a transthoracic biopsy revealing a spindle cell neoplasm both estrogen and progesterone receptor positive consistent with leiomyoma which histologically matched her prior hysterectomy specimen.
Benign metastasizing leiomyoma (BML) is a rare entity with less than 100 documented cases published in the medical literature usually as scattered case reports. BML originates from an antecedent leiomyoma of the uterus in virtually all cases. The affected women are usually asymptomatic and present with multiple lesions incidentally discovered on routine chest radiographs. Typically, these women had undergone hysterectomy for benign leiomyomas several months to many years earlier.
Despite the high incidence of uterine leiomyomas in the general population, BML is a rare condition. The origin of the tumor remains controversial, however they are generally considered to be hematogenous metastases of uterine leiomyomas via pelvic venous channels to extrauterine organs, the lung being the most common site of involvement.
BML characteristically presents as numerous well-defined pulmonary nodules of varying size ranging from a few millimeters to several centimeters that may rarely cavitate. The nodules typically neither calcify nor enhance following intravenous contrast injection. Characteristic imaging findings are shown in Figures 1-3 above. Other multifocal lung lesions that should be differentiated from BML include malignant metastatic disease (i.e. colon, sarcoma); lymphoma; and infectious etiologies (fungal).
BML tumors typically respond to hormonal therapy and have a benign course, showing regression on progesterone treatment and progression on estrogen regimen. Malignant transformation has not been reported, nevertheless regular follow-up is recommended.
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