Rare pulmonary primitive neuroectodermal tumor metastasizing to the right atrium: a case report.

A 28-year-old man complained of intermittent irritable dry cough for 2 months with occasional bloody sputum. Positron emission tomography-computed tomography (PET-CT) suggested multiple heterogeneous soft tissue masses in the inferior lobes of both lungs, with heterogeneous increases in 18F-FDG uptake. No metabolic disorders were found in the rest of the body. CT-guided percutaneous lung puncture and biopsy and immunohistochemical study confirmed pulmonary primitive neuroectodermal tumor (PNET). PNET is characterized by small round blue cells and positive CD99 expression. After six cycles of chemotherapy with ifosfamide, dacarbazine and cisplatin, the lesions diminished substantially. At 2 months after the last cycle of chemotherapy, the patient complained of exertional dyspnea. PET-CT and echocardiogram suggested a space-occupying lesion in the right atrium. Autopsy revealed that this space-occupying lesion had the same pathomorphology and immunophenotype with pulmonary PNET, suggesting metastasis of pulmonary PNET to the right atrium. Here, we reported this rare case of pulmonary PNET metastasizing, instead of direct infiltrating or extending, into the heart.