A Hypercalcemic Enigma: A Rare Case of Bone Marrow Sarcoidosis.

Sarcoidosis is a multisystem inflammatory disease involving granuloma formation. The exact etiology of the disease remains unknown. While the lungs are the most commonly involved organs in sarcoidosis, bone marrow-only involvement is quite rare. As bone marrow-only involvement can have a presentation that closely resembles multiple myeloma, a significant diagnostic dilemma can occur as the treatment for sarcoidosis is different compared to multiple myeloma. We present a case of a 62-year-old female who presented with worsening lower extremity weakness and fatigue. She was found to have new-onset hypercalcemia, normocytic anemia, and lytic bony lesions. Extensive laboratory workup for multiple myeloma was negative with bone marrow biopsy showing non-caseating granulomas, thus diagnosing the patient with sarcoidosis involving the bone marrow.