Vertebral Sarcoidosis Mimicking Metastatic Disease in a Patient With Prior Melanoma: A Diagnostic Challenge.

Sarcoidosis is a multisystemic granulomatous disease that most commonly affects the lungs and intrathoracic lymph nodes. Osseous involvement is uncommon, and vertebral disease is particularly rare, often mimicking metastatic malignancy and posing a significant diagnostic challenge. We report the case of a 51-year-old woman with a history of resected melanoma who was incidentally diagnosed with sarcoidosis following abnormal findings on screening mammography. Subsequent evaluation revealed pulmonary involvement. Months later, she developed acute back pain following minor trauma, and magnetic resonance imaging (MRI) demonstrated multifocal vertebral marrow lesions concerning for metastatic disease. However, computed tomography (CT) failed to demonstrate corresponding structural abnormalities. Definitive diagnosis was established through vertebral biopsy, which revealed noncaseating granulomatous inflammation consistent with sarcoidosis, with no evidence of malignancy or infection. The patient demonstrated clinical improvement with corticosteroid and immunosuppressive therapy. This case highlights the importance of considering sarcoidosis in the differential diagnosis of vertebral lesions, particularly in patients with a history of malignancy, and underscores the need for histopathological confirmation in cases with discordant imaging findings.