SAT-501 A Rare and Potentially Fatal Etiology of Hypercalcemia in an Infant

Abstract

Background: Increased 1alpha-hydroxylase activity in granulomatous diseases is a well-defined cause of hypercalcemia. Disseminated fungal infections are a rare cause of granulomatous diseases in immunocompetent children. Clinical Case: A 7-month-old female presented with failure to thrive and vomiting for 2 months. Initial tests showed Hgb 10.9 g/dL, WBC 4.2k/uL (37% Neutrophil), total Ca 17.9 mg/dL, iCa 2.43 mmol/L, Mg 2.4 mg/dL, Phos 4.8 mg/dL, AST 102 IU/L, ALT 115 IU/L, albumin 4.4 g/dL, PTH 5.3 pg/mL (RR 10-65), 25-OHD 61.3 ng/mL, 1,25-(OH)2D 146 pg/mL (RR 19-79). Abdominal US showed an enlarged, heterogeneous liver parenchyma and splenomegaly. Calcium level did not respond to calcitonin. She received pamidronate IV 0.5 mg/kg total over 2 days. Initial workup for infectious, hematologic, oncologic and immunologic etiologies was negative. She had a G-tube and was discharged after achieving adequate weight gain and normal Ca (9.5 mg/dL). Three weeks later she returned with vomiting and hypercalcemia (13.5 mg/dL). She started prednisolone PO 1 mg/kg/day for hypercalcemia. Clinical and biochemical markers improved and she was discharged home on steroid. Six-weeks later, while on prednisolone, she presented with fever and hypotension. A stat CBC showed pancytopenia (Hgb 8 g/dL, WBC 2.4k/uL, Plt 23k/uL) and fungal elements in peripheral smear. Admitted to ICU for anti-fungal and supportive treatment. Serum Histoplasma antigen was mildly positive at 2.4 U/mL (negative <2). Bone marrow aspirate showed phagocytic histiocytes. Liver biopsy demonstrated lobular histiocytic infiltrate with rare granulomas and increased portal/periportal and pericellular fibrosis with bridging confirming the granulomatous disease. Extensive immunological tests did not identify any underlying immunodeficiency. She had a normal SNP microarray but a heterozygous mutation in the UNC13D gene, this was classified as a variant of unknown significance. No deletion or duplication was found in HLH gene panel. After one month of amphotericin B IV treatment, her clinical status improved and discharged home. She took itraconazole PO treatment for 9 months and made full recovery. Serum and urine Histoplasma antigens remained negative during and after completion of antifungal therapy. Steroid slowly tapered while Ca and vitamin D levels remained normal. Conclusion: Hypercalcemia can be the presenting sign of a potentially fatal disseminated fungal infection even in immunocompetent children. Although prednisolone has corrected hypercalcemia in this case, it has likely contributed to the dissemination of the unmasked fungemia. Extra caution should be used before considering steroid treatment for hypercalcemia and ideally, it should be delayed until after anti-fungal treatment begins once the correct diagnosis is reached.