Abstract Disclosure: O.A. Aluko: None. I. Singh: None. Introduction: Hypercalcemia has been described in patients with most granulomatous disorders, of which sarcoidosis and tuberculosis are the most common. Granuloma formation is a rare, however well known complication of silicon implants and injections. We present a case of silicon granulomatosis induced hypercalcemia in a transgender female. Case Report 60-year-old transgender female, with past medical history of HIV on HAART was referred to Endocrinology for evaluation of hypercalcemia. She Bloodwork done a few weeks prior revealed elevated calcium 12.3 and low PTH of 9. Reported symptoms include worsening abdominal pain similar to prior gastritis flare, insomnia and significant weight loss. Denied any constipation, joint pain, mood changes, no history of bone fractures or kidney stones. Admitted to significant dairy intake - half a gallon of milk within 3 days and daily yogurt consumption. Endorsed inadequate daily fluid intake and she was not taking oral calcium or Vitamin D supplementation. Quit tobacco 9 years ago. Vitals were significant for tachycardia with HR 120/min, BP stable. Patient was referred to the ER for IV hydration and further evaluation with initial suspicion of malignancy. Repeat corrected calcium was 14.7, ionized calcium 6.8, PTHrP undetectable <2, borderline high 1,25 dihydroxyvitamin D 74.5, low vitamin D 17.9 and normal free T4 1.5. ACE, SPEP, UPEP levels within normal limits. Vitamin A low. CT chest/abdomen/pelvis revealed innumerable soft tissue foci in the subcutaneous adipose tissue of the flanks and lateral gluteal areas; nodular liver, suspected cirrhosis and portal hypertension. Imaging findings prompted further discussion regarding prior procedures. She endorsed history of silicone fillers in hips and breast implants 30 years ago. Images reviewed with radiology confirmed calcification around bilateral breast implants, with intracapsular rupture. Calcium improved with IV Fluids, bisphosphonates and steroids. The most probable cause of hypercalcemia was believed to be secondary to silicone granulomatosis. Innumerable granulomas were deemed irresectable, removal of the breast implants considered however not performed. She was later diagnosed with hepatitis B, cirrhosis and succumbed to sepsis and multiorgan failure. Conclusion Eliciting a detailed history, physical exam and correlating with imaging findings is imperative to establishing an uncommon diagnosis. PTHrP was low and there were no bony metastases making the possibility of malignancy related hypercalcemia less likely. FDG-PET if performed would reveal hypermetabolic nodules, often an initial indication to the underlying etiology. Presentation: 6/2/2024