Background: Inflammatory pseudotumor of the lung involves a benign, non-neoplastic lung lesion of unknown etiology.
Case Report: We present a case of a 60-year-old female smoker who had been under intermittent immunosuppressive medication for discoid lupus, who was admitted to hospital with fever of 39.5°C of 10-day duration, not responding to an oral cephalosporin. Chest CT examination showed a cavitating opacity in the upper zone of the left lung. It was not feasible to establish a diagnosis based on clinical and laboratory testing nor based on CT scanning and bronchoscopy. Thus, the patient underwent left thoracotomy and sphenoid resection of the lesion, which was sent for biopsy. The histopathologic features aided by immunohistochemical staining proved the lesion to be an inflammatory pseudotumor of the lung.
Conclusions: The case is reported because of the extremely rare radiologic presentation of the development of a lung pseudotumor emerging as a cavitated lesion, which relapsed during the follow-up period while the patient was still under immunosuppressive medication.

Keywords: Plasma Cell Granuloma, Pulmonary - immunology, Plasma Cell Granuloma, Pulmonary - radiography, Plasma Cell Granuloma, Pulmonary - surgery, Plasma Cell Granuloma, Pulmonary - therapy