Sarcoidosis with Rare Extrapulmonary Involvement.

Sarcoidosis is a systemic granulomatous disease in which medullary involvement is a rare extrapulmonary manifestation. We present the case of a 37-year-old man with right abdominal and dorso-lumbar pain lasting for months. Computerized tomography showed renal microlithiasis and retroperitoneal, hilar and mediastinal adenopathies. Laboratory results showed an elevated erythrocyte sedimentation rate, IgG, β2-microgobulin and angiotensin-conversion enzyme, serum calcium in the upper limit and hypercalciuria. There was a slight elevation of the CD4/CD8 ratio in bronchoalveolar lavage, without lymphocytic alveolitis. An endobronchial ganglion biopsy was inconclusive. A positron emission tomography scan demonstrated supra and infra-diaphragmatic, splenic and medullary involvement, suggesting lymphoproliferative disease (LPD). A bone marrow biopsy (BMB) revealed sarcoid-like epithelioid cell granulomas, excluding LPD. Sarcoidosis was assumed and corticosteroids were started. Although cytopenias were not present, the extensive ganglion, splenic and medullary involvement made LPD exclusion imperative, while BMB allowed for a definitive diagnosis. LEARNING POINTS: Sarcoidosis is a multisystemic granulomatous disease in which medullary involvement is a rare extrapulmonary manifestation.Bone marrow biopsy is rarely performed based on serial blood counts, which may be associated with underdiagnosis.FDG-PET cannot reliably distinguish between sarcoidosis and lymphoproliferative disease as the cause of extensive ganglion, splenic and bone marrow involvement, and so a high index of clinical suspicion is required. © EFIM 2021.