Disseminated Peritoneal Leiomyomatosis With Unusual Lung Mesenchymal Malignant Transformation.

Disseminated peritoneal leiomyomatosis (DPL) is a benign metastasis of leiomyoma mimicking metastasis of malignancy. It usually affects premenopausal women. Malignant transformation is a rare clinical scenario of DPL. However, its etiology is unknown with unusual growth patterns, either of which makes the diagnosis difficult. It was postulated that the pathophysiology of DPL is metaplasia of mesothelial cells under the effect of hormonal stimulation. Hence, we reported the case of a 62-year-old woman with a history of left breast cancer, who presented with DPL and metastasis to the lung with malignant transformation after two years of starting prophylactic tamoxifen therapy. The influence of tamoxifen use on the development of DPL is not fully understood; this is a rare case that highlights a possible association between tamoxifen and the malignancy transformation of DPL. Hence, it may help raise awareness among clinicians dealing with women using tamoxifen or other hormonal therapy, and the risk of DPL development with potential malignant transformation in such patients.