Endobronchial epithelioid leiomyoma (leiomyoblastoma) causing complete right-lung atelectasis

Rationale: Endobronchial epithelioid leiomyoma, historically termed leiomyoblastoma, is an exceptionally rare smooth-muscle tumor that can cause critical airway obstruction and mimic malignant endobronchial disease. Patient concerns: A 45-year-old never-smoking woman presented with several months of progressive exertional dyspnea and a persistent dry cough. Examination revealed absent breath sounds over the right hemithorax and rightward tracheal deviation. Diagnoses: Chest radiography and computed tomography demonstrated complete right-lung atelectasis with ipsilateral mediastinal shift. Bronchoscopy showed a smooth, white mass completely occluding the right main bronchus. Biopsy was deferred because an endobronchial hydatid cyst and a vascular tumor remained possible. Histopathology after resection showed epithelioid cells with clear-to-eosinophilic cytoplasm, minimal atypia, <2 mitoses/10 high-power fields, and focal coagulative necrosis. Tumor cells were diffusely positive for desmin, with focal weak cytokeratin and vimentin positivity; Ki-67 was below 5%. Interventions: Right posterolateral thoracotomy revealed a polypoid tumor arising from the right upper-lobe bronchus and extending into the right main bronchus. Because the upper lobe was extensively destroyed and the fissural anatomy precluded meaningful parenchymal preservation, right upper and middle bilobectomy was performed while preserving the lower lobe. Outcomes: Resection margins and lymph nodes were tumor-free. The right lower lobe re-expanded satisfactorily, recovery was uneventful, and the patient remained asymptomatic approximately 13 months after surgery. Lessons: Rare benign endobronchial tumors can cause complete unilateral lung collapse. Complete resection with maximal feasible parenchymal preservation is essential, and long-term surveillance is warranted because of uncertain biological behavior.