Pseudotumor

A 45-year-old man with a history of congestive heart failure presented with cough and dyspnea. A chest roentgenogram showed loculated pleural effusion in the horizontal fissure of the right lung (A), and a CT scan revealed pleural-based density in that lung (B). The patient was treated with diuretics and angiotensin-converting enzyme inhibitors. Ten days later, a repeated CT scan showed that the effusion had completely resolved (C).

Dr Bijoy E. John of Nashville, Tenn, writes that a loculated pleural effusion that resolves with treatment is known variously as pseudotumor, vanishing tumor, and phantom tumor and can be the earliest sign of cardiac compression. In three quarters of all cases, pseudotumors occur in the horizontal fissure of the right lung. The mechanism is not understood, but local inflammation is not the cause.¹ In the posteroanterior view of a chest film, pseudotumors are usually mistaken for bronchogenic carcinoma. The lateral view, however-as seen here-shows them to be typically elliptic, with edges blending imperceptibly into the fissures.² Other differential diagnoses include paraffinomas caused by aspiration of mineral oil,³ intrapulmonary rheumatoid granulomas,⁴ and pulmonary infarction.⁵ The response to therapy varies, but complete resolution occurs with diuresis.

REFERENCES:1. Meier MA, Helfrich GB, Levitsky S. Phantom tumor of the lung. JAMA. 1971;218:1571.
2. Fraser RG, Par JAP. Diagnoses of Diseases of the Chest: An Integrated Study Based on the Abnormal Roentgenogram. Philadelphia: WB Saunders Co; 1970;362, 1156.
3. Genereux GP. Lipids in the lungs: radiologic-pathologic correlation. J Can Assoc Radiol. 1970;21:2-15.
4. Panatierre F, Chandler BF, Libcke JH. Pulmonary cavitation in rheumatoid disease. Am Rev Respir Dis. 1968;97:89-95.
5. Miller JI, Harrison EG Jr, Bernatz PE. Surgically treated unsuspected pulmonary infarction. Ann Thorac Surg. 1972;14:181-188.