Sarcoidosis With Skeletal Involvement Masquerading as Metastatic Malignancy.

Sarcoidosis is a systemic disorder characterized by noncaseating granuloma formation, which can affect any organ in the body; however, skeletal involvement is relatively uncommon. This case report presents a rare case of sarcoidosis primarily affecting the skeletal system in a 39-year-old man with a history of neurosarcoidosis. The patient presented with symptoms of nausea, vomiting, fatigue, weight loss, and lower back and pelvic pain, which were initially suspicious for malignancy. Computed tomography scans revealed lytic bone lesions and lymphadenopathy. However, a biopsy of a left inguinal lymph node confirmed necrotizing granulomatous lymphadenitis, which was consistent with necrotizing sarcoid granulomatosis - a rare variant of sarcoidosis. The patient was treated with systemic corticosteroids, which led to clinical improvement. The prognosis of sarcoidosis is generally good, with spontaneous remission occurring in up to two-thirds of patients; however, some patients may develop chronic and/or progressive disease. In particular, patients with a history of neurosarcoidosis may be at an increased risk for chronic or recurrent disease. This case highlights the importance of considering sarcoidosis in the differential diagnosis of patients presenting with nonspecific symptoms and lymphadenopathy, even in the absence of pulmonary involvement.