Nodular Pulmonary Sarcoidosis with a B-cell Reaction Similar to That of IgG4-related Disease.

A 66-year-old man presented to our hospital following the detection of abnormal chest shadows during a previous medical checkup. Chest computed tomography revealed multiple small nodules in both lungs, and surgical biopsy was performed for the diagnosis. A histological examination of the pulmonary nodules revealed small non-caseating epithelioid cell granulomas with prominent infiltration of lymphocytes and IgG4-positive plasma cells. The patient was eventually diagnosed with pulmonary sarcoidosis, with a B-cell response similar to that of IgG4-related disease. This report provides insight into sarcoidosis with histopathological features similar to those of IgG4-related diseases.