Solitary thin-walled cystic lung cancer with extensive extrapulmonary metastasis A case report and review of the literature

Rationale: Asymptomatic, isolated, and thin-walled cystic lung cancer with extensive extrapulmonary metastasis is rare, and the risk of pulmonary cyst developing into lung cancer is poorly understood. The efficacy of apatinib for end-stage pulmonary adenosquamous carcinoma has not been clarified yet. Patient concerns: We herein report a rare case of primary lung cancer that appeared as an isolated thin-walled cystic lesion on computed tomography (CT) image, who was initially misdiagnosed as having pulmonary cyst empirically. Diagnoses: Fluorine-18-fluorodeoxyglucose-positron emission tomography and CT-guided liver biopsy of the patient revealed extra-pulmonary metastasis of lung cancer. Interventions: Eight cycles of cisplatin-based chemotherapy were administered, followed by oral apatinib for 6 months. Thereafter, best supportive care was given for this patient. Outcomes: The pulmonary cystic lesion indicated stable disease through the therapy, but the hepatic tumors were progressed gradually after anticancer treatment. The patient died 16 months after the correct diagnosis. Lessons: Solitary thin-walled cystic lung cancer should be kept in mind during the differential diagnosis of pulmonary cavitary lesions. Chest CT alone is insufficient for surveillance of these cystic diseases. Timely biopsy and resection are essential to avoid delayed management. Besides, apatinib may play a role in the treatment of end-stage pulmonary adenosquamous carcinoma.