An Interesting Case of Isolated Bone Marrow Sarcoidosis

Introduction: About 30% cases of sarcoidosis have extrapulmonary manifestations but only 7% of patients present without any lung involvement. Among those 7%, most of the patients have manifestations on the skin but isolated bone marrow sarcoidosis has not been commonly reported. This case represents an unusual manifestation of isolated bone marrow sarcoidosis presenting with very high calcium levels. Case Presentation: A 58-year-old female presented to us with fatigue, poor appetite, and nausea. She did not report any weight changes. Her cancer screening was up to date. On examination, she appeared dehydrated. No neck swelling was appreciated. Cardiac, respiratory, abdominal, and neurological examinations were normal. Complete blood count showed hemoglobin of 10.6 mg/dL, white blood cell count of 3.8 k/dL, and platelet count of 87 x10(9)/L. Metabolic panel revealed hypercalcemia with corrected calcium levels as high as 12.6 mg/dL. Ionized calcium was 8.1 mg/dL (normal 4.8 - 5.6). Her parathyroid hormone (PTH) level was elevated up to 64.6 mg/dL and then further increased to 134.3 mg/dL. A 24-hour urinary calcium level was normal. 1, 25-dihydroxy (1,25-OH) and 25-OH vitamin D levels were 97 mg/dL (normal 18–72) and 31.2 mg/dL, respectively. Serum protein electrophoresis and light chain analysis were normal. Hyperparathyroidism was suggested as a cause of hypercalcemia. Ultrasound of the neck and sestamibi scan showed a right lower pole parathyroid adenoma. Paraneoplastic hypercalcemia was also one of the differentials. Parathyroid hormone related peptide (PTHrP) was 9 pg/mL (normal 14 - 27). Colonoscopy was normal. Computerized tomography showed normal lungs, liver and spleen. No masses and lymphadenopathy was seen. A bone marrow biopsy was done for pancytopenia. Patient underwent parathyroid adenoma removal followed by a drop in serum calcium level (8.2 mg/dL). Patient was discharged on calcium carbonate and vitamin D tablets. Upon outpatient follow-up, calcium level started to rise again up to 9.8 mg/dL. Despite discontinuation of supplemental calcium and vitamin D, calcium continued to uptrend (11.5 mg/dL 4 weeks later). Angiotensin converting enzyme (ACE) level came back as high as 129 (normal level < 40 mcg/L). Meanwhile, the bone marrow biopsy results showed that 40% of bone marrow was occupied by non-caseating granulomas suggesting sarcoidosis. Patient was started on steroids for isolated bone marrow sarcoidosis, and eventually her serum calcium level normalized. Conclusion: An isolated bone marrow sarcoidosis is an extremely rare manifestation of extrapulmonary sarcoidosis. It can present with pancytopenia and should be sought in patients with persistent hypercalcemia. In addition, our case was challenging due to the presence of a concurrent hyperparathyroidism which was initially thought to be the only explanation of our patient’s hypercalcemia.