Case Report: Pulmonary fibroleiomyomatous hamartoma presenting as a giant exophytic multilocular cystic lesion.

Pulmonary fibroleiomyomatous hamartoma (PLH) is a rare benign subtype of pulmonary hamartoma. It typically presents on imaging as a well-circumscribed solid pulmonary nodule. The lesion can arise in any region of the lung. There is a slight female predominance, and most patients are asymptomatic or present with mild, non-specific respiratory symptoms such as cough and sputum production. In most cases, the lesion is incidentally detected during routine health examinations or imaging studies performed for unrelated conditions. This case report describes a 55-year-old woman in whom a cystic abnormal lesion with areas of air lucency was incidentally detected in the right upper lobe during a routine health examination. The lesion appeared as a large space-occupying mass with cystic wall enhancement on imaging, and a congenital cystic lesion was initially suspected. After admission, the patient underwent thoracoscopic wedge resection of the right upper lobe lesion. Intraoperatively, the tumor demonstrated a pedunculated exophytic growth pattern with a narrow stalk. Postoperative histopathological examination revealed a biphasic architecture composed of epithelial and mesenchymal components. Immunohistochemical findings, together with the histopathological features, favored the diagnosis of pulmonary fibroleiomyomatous hamartoma. The patient recovered uneventfully after surgery, and no evidence of recurrence was observed during the available follow-up period. To our knowledge, this is the first reported case describing a pulmonary lesion favoring the diagnosis of pulmonary fibroleiomyomatous hamartoma that presents predominantly as a giant exophytic multilocular cystic lesion. The patient had a previous history of hysterectomy for uterine leiomyoma, and the lesion showed positive expression of estrogen receptor (ER) and progesterone receptor (PR), suggesting a potential hormonal association. This case highlights that pulmonary fibroleiomyomatous hamartoma should be considered in the differential diagnosis of pulmonary lesions in female patients with a history of uterine leiomyoma, even when imaging findings demonstrate atypical cystic features, to reduce the risk of misdiagnosis.