呼吸器症状を伴わずに偶発腫瘍として診断された後腹膜リンパ脈管筋腫症(LAM : lymphangiomyomatosis) の1例

Abstract

A 39-year-old woman presented with a large retroperitoneal tumor found incidentally in a routine examination. The 138×37×26 mm mass was located in the left paraaortic region. Blood tests and urinalyses including endocrinological examinations revealed no abnormalities. A chest computed tomography revealed multiple thin-walled pulmonary cysts, which is a characteristic of lymphangioleiomyomatosis (LAM). Because the findings strongly suggested that the retroperitoneal tumor was an extrapulmonary manifestion of LAM, we performed laparoscopic resection of the tumor for diagnosis and treatment. The pathological diagnosis was LAM. The tumor cells were immunohistochemically positive for α -smooth muscle actin and weakly positive for HMB45, which is consistent with LAM. The cells were also positive for estrogen receptor (ER) and progesterone receptor (PgR). LAM is a rare progressive disease that affects mainly the lung, and leads to chronic respiratory failure. Extrapulmonary LAM without respiratory symptoms, is extremely rare. In the past, the prognosis of LAM was poor, with a median survival of 8-10 years, but now 85% survive more than 10 years. In the present case, deterioration of pulmonary lesions was not observed during the 10 months follow-up. Because ERand PgRfindings were positive, we will consider hormonal therapy as a treatment option, when the pulmonary lesions progress in the present case.