肺転移性平滑腫瘍症：転移性疾患を模倣した肺多発性平滑筋腫

Pulmonary benign metastasising leiomyoma is a rare condition characterised by multiple smooth muscle tumours in the lungs, typically in women with a history of uterine leiomyoma. We report a case of a woman with a previous hysterectomy who developed multiple pulmonary nodules, initially misdiagnosed as hydatid disease or metastatic cancer. Surgical resections and histopathological examination revealed benign leiomyomas composed of mature smooth muscle cells without necrosis or mitoses. Immunohistochemistry was positive for vimentin, desmin and smooth muscle actin, confirming the diagnosis despite a high Ki-67 index. The course was complicated by spontaneous pneumothorax, followed by staged thoracotomies with bilateral tumour removal and subtotal thyroidectomy. This case emphasises the diagnostic challenge of pulmonary leiomyomatosis, the importance of morphological and immunohistochemical verification and the role of individualised surgical management with long-term follow-up in selected symptomatic cases.