Large Cell Carcinoma Tumor Appears on Anteroposterior Bucky Film

Except for a fever of 1 month's duration, a 28-year man had no other complaints. He said he used to smoke marijuana but never used intravenous drugs. His temperature was 39.4°C (103°F), but no other abnormalities were noted on physical examination.

A lateral chest film showed an anterior mediastinal tumor (arrow). A posteroanterior film demonstrated the hilum overlay sign (arrow), in which the configuration of the anterior mediastinal tumor simulates an enlarged heart; the lungs appeared normal. Contrast-enhanced CT of the chest revealed mediastinal lymphadenopathy (arrow) with foci of necrosis.

Results of all laboratory investigations were negative. These included HIV antibody test, tuberculin skin test with 5TU of purified protein derivative, and examination of induced sputum smears and cultures for acid-fast bacilli. A CT-guided needle biopsy revealed poorly differentiated large cell carcinoma.

Despite extensive diagnostic evaluation, the source of a primary tumor could not be identified. Dr Samer Alkhuja of Greenwich, Conn, writes that the patient responded well to combined radiation and chemotherapy, and his condition was stabilized within 6 months.

Surprisingly, an anterior mediastinal mass may closely resemble a dilated heart or pericardial effusion. The hilum overlay sign may be helpful in making this distinction. It is best shown on the anteroposterior Bucky film, in which the tumor is magnified more than the heart behind it, thus accentuating the discrepant position of the left pulmonary artery.¹

REFERENCE:
1. Felson B, ed. Chest Roentgenology. Philadelphia: WB Saunders Co; 1973: 40, 390-391.