Dual pathology: paraneoplastic sarcoidosis emerging at the time of progression from smouldering to symptomatic myeloma.

Sarcoidosis is a systemic disease of unknown aetiology, which is diagnosed based on the presence of non-caseating granulomas on histology. The occurrence of sarcoidosis or a sarcoidosis-like reaction with malignancy has been recognised for several years. Although it has been established that there is an increased risk of lymphoproliferative disorder with sarcoidosis, the association between multiple myeloma and sarcoidosis has rarely been reported.