Plasma cell granuloma of the lung: Difficulties in diagnosis and prognosis

Background. The nature of plasma cell granuloma of the lung is still not well defined. Its diagnosis can be difficult, and its long-term prognosis is uncertain. Methods. Four patients, aged 4 1/2 to 45 years, had resection of a circumscribed plasma cell granuloma. In 1 of them, it was associated with a carcinoma. The fifth patient was treated by irradiation for an invasive form of plasma cell granuloma, which was diagnosed as malignant lymphoma 1 year later. The plasma cell granulomas had a similar polymorphic pattern and were polyclonal at immunohistochemistry. Results. The 3 patients treated by lobectomy, including the patient with an associated carcinoma, were alive and well at 12, 12, and 11 years postoperatively. The patient treated by pneumonectomy had recurrence 9 years later and died 11 years after operation: irradiation was not effective. The patient with lymphoma was treated by chemotherapy and was alive and in remission 5 years later. Conclusions. An accurate preoperative diagnosis is difficult. The results of biopsy can be inconclusive, and an associated malignancy can be missed. Complete resection remains the best treatment. The long-term prognosis is unpredictable, and late and fatal recurrences are possible.