5117 Unusual Sarcoid Presentation as a Case of Hypercalcemia

Abstract Disclosure: M. Salim: None. A. Chauhan: None. S. Avula: None. A. Ahmed: None. K. Zekarias: None. Background: Hypercalcemia may arise from a variety of causes and can pose challenging diagnostic dilemma. Clinical Case: An 89-year-old male presented with worsening malaise related to persistent hypercalcemia. He reported productive cough, polyuria, polydipsia, generalized muscle weakness and weight loss. Physical exam was remarkable for upper and lower extremities weakness. Laboratory tests showed calcium 11.6 (8.8-10.2 mg/dL), phosphorus 2.8 mg/dL (2.5-4.5 mg/dL), albumin 4.2 g/dL (3.5-5.2 g/dL), parathyroid hormone (PTH) 10 pg/mL (15-65 pg/mL), parathyroid hormone-related protein (PTH-rp) 4.5 pmol/L (0.0-2.3 pmol/L), TSH 6.24 (0.30 - 4.20 uIU/mL), free T4 1.10 ng/dL (0.90-1.70 ng/dL), GFR 61 mL/min/1.73m2, 25 OH Vit D 31 ng/mL (20-75 ng/mL), vit D 1,25-dihydroxy 134 pg/mL (19.9-79.3 pg/mL), calcium urine/creatinine 0.54. Hypercalcemia was first noted 11 months before the visit with a level of 14.0 mg/dL (8.8-10.2 mg/dL), phosphorus 3.5 mg/dL, PTH 11, PTH-rp 1.4 pmol/L, 25 OH Vit D 62 ng/mL, Vit D 1,25-dihydroxy 90 pg/mL, angiotensin-1-converting enzyme 12 U/L (16-85 U/L), serum and urine electrophoresis showed no monoclonal gammopathy present, and tuberculosis interferon-gamma test negative. Autoimmune workup was unremarkable, except for weak positive anti-signal recognition particle (SRP) antibodies and anti-Mi-2 antibodies. CT chest/pelvis/abdomen demonstrated peripheral predominant reticular opacities suggestive of interstitial lung disease and no malignant findings. Treatment history included zoledronic acid 11 months before the visit. The patient was referred for a granulomatous disease workup.Upon one month follow-up, the hypercalcemia symptoms were worsening. Repeat calcium was 12.3 mg/dL and fungal serologies were negative. The patient was started on prednisone empirically. PET CT was ordered and revealed patchy inflamed musculature of extremities suspicious of dermatomyositis/polymyositis. Further labs showed unremarkable myomarker panel, u3-Hydroxy-3-Methylglutaryl Coenzyme A reductase (HMGCR) antibody, Anti-cN-1A antibody, ACE 53 U/L, creatine kinase 32 U/L (39-309 U/L), aldolase 5.4 U/L (1.2-7.6 U/L), soluble IL-2R 1,021 U/mL (137-838 U/mL), and lysozyme 3.89 ug/mL (<2.75 ug/mL). A muscle biopsy was done, which showed benign skeletal muscle with patchy myofiber atrophy, patchy interstitial fibrosis, and focal interstitial mild chronic inflammation with no evidence of sarcoid granulomas in the sample. One week lab follow-up post initiation of steroid showed calcium of 10.1 mg/dL and subsequently improvement in his overall labs. Working diagnosis of sarcoid myositis was made. Conclusion: This case report highlights the approach of diagnosing a rare case of hypercalcemia due to sarcoid myositis. In a highly clinical suspicious patient, PET CT scan might be a necessary modality for diagnosis. Presentation: 6/2/2024