Idiopathic multicentric Castleman disease developing after a diagnosis of sarcoidosis: A case report and literature review.

A 72-year-old woman presented with an abnormal shadow on chest radiograph. She was histologically diagnosed with sarcoidosis 20 years previously, and prednisolone was initiated 8 years previously. Computed tomography revealed centrilobular micronodules and bronchovascular bundle thickening in both lungs with multicentric lymphadenopathies; multiple pulmonary nodular lesions appeared during prednisolone tapering. Laboratory findings included polyclonal hypergammaglobulinemia and elevated interleukin-6 levels. Surgical lung biopsy revealed marked lymphoplasmacytic infiltration with lymphoid aggregates. The patient tested negative for human herpesvirus-8 and clinically diagnosed with idiopathic multicentric Castleman disease. The coexistence of sarcoidosis and Castleman disease is rare; this case improved with additional tocilizumab treatment.