A rare case of primary pulmonary inflammatory pseudotumor-like follicular dendritic cell sarcoma successfully treated by lobectomy.

Primary pulmonary inflammatory pseudotumor-like follicular dendritic cell sarcoma (IPT-like FDCS) is extremely rare. Here, we report a case of a 64-year-old female with primary pulmonary IPT-like FDCS. The patient was found to have a solid nodule in the right lower lobe (RLL) of the lung incidentally without any symptoms or signs of discomfort. The chest computed tomography (CT) showed that there was an irregular nodule in the basal segment of the RLL, approximately 2.0 cm × 1.1 cm × 1.0 cm in size, of 15 HU in CT value. While the result of the fiberoptic bronchoscope-guided biopsy of the mass showed that there was inflammatory cell infiltration, no evidence of malignancy was found. After a thorough discussion of the multidisciplinary team, lobectomy of the RLL and systematic lymph node dissection were performed for the patient. Histologic analysis of the resected mass revealed infiltration of a large number of lymphocytes and plasma cells with the expression of CD21, CD23, CD35 were positive. In addition, the Epstein-Barr virus (EBV) probe hybridization were positive. As a result, the diagnosis of EBV-positive IPT-like FDCS was strongly supported. No recurrence or any signs of metastasis were found during a 10-month follow-up time. As we have reported in this rare case, the diagnosis of primary pulmonary IPT-like FDCS should be considered even when there is only lymphoplasmacytic infiltration and no evidence of malignant tumor cells in the lung.