Primary Pulmonary Myxoid Malignant Fibrous Histiocytoma

Primary pulmonary malignant fibrous histiocytoma (MFH) is a rare mesenchymal neoplasm of the lung. Myxoid variant is an uncommon subtype of primary pulmonary MFH. In this report we present a case of a young adult who had chest discomfort and was found to have a huge mass in the left lung. Left pneumonectomy was performed and a myxoid variant of primary pulmonary MFH was proven by immunohistochemistry. Intercostal color-doppler ultrasound showed a heterogeneous cystic mass with internal echogenicity of the cystic content and thick wall but without obvious blood flow. The chest CT showed a huge cystic mass in the lung parenchyma with mural nodules. MRI demonstrated more findings than CT, including chest wall invasion and characteristic signal intensity of the cystic content compatible with mucin. The imaging findings of this myxoid variant of primary pulmonary sarcoma with cystic change were unique and correlated with pathologic diagnosis.