Systemic Sarcoidosis With Neurosarcoidosis Features as a Risk Factor for Multifocal Osteonecrosis.

Sarcoidosis is a systemic inflammatory disease that affects diverse organs such as the lungs, skin, eyes, and brain. Osseous involvement in sarcoidosis usually affects bones of the appendages with direct infiltration of non-caseating granulomas without bony infarcts. Symptoms of sarcoid bone lesions respond well to corticosteroid therapy. In contrast, corticosteroids act as a risk factor for the development of osteonecrosis resulting in pain and disability. Osteonecrosis that involves three or more different anatomic sites, defined as multifocal osteonecrosis (MFON), is rare. MFON has not been documented in the setting of sarcoidosis. We report a systemic sarcoidosis patient with predominant neuropsychiatric manifestations, who progressively developed MFON. Despite the limited use of corticosteroid treatment, the high burden of systemic sarcoidosis and its related neuropsychiatric involvementmay have collectively contributed to the development of MFON. This case highlights the rare association of MFON with systemic sarcoidosis and the need for further investigation into the underlying pathogenesis of MFON to prevent disability and morbidity.