Malignant hypercalcemia as the debut of acute lymphoblastic leukemia in a pediatric patient-a diagnostic and therapeutic approach: Case report

Background

Hypercalcemia is a rare metabolic disorder in the pediatric population, with several differential diagnoses that resemble hematologic malignancies. In cases of severe hypercalcemia, therapeutic strategies other than hyperhydration, such as the use of bisphosphonates, have been described.

Case presentation

We present the case of a previously healthy 12-year-old boy who was admitted to the emergency department due to fatigue, hypo-responsiveness, and progressively worsening poor appetite for the previous 19 days. Initial laboratory tests revealed severe hypercalcemia (total calcium: 19 mg/dl), hyperphosphatemia, elevated creatinine, and hyperuricemia. Management with hyperhydration and xanthine oxidase inhibitor (allopurinol) was provided. The patient was transferred to the pediatric intensive care unit where treatment with furosemide, systemic corticosteroid, and zoledronic acid was started. Metabolic, infectious, renal, and endocrinological causes were excluded. Follow-up paraclinical studies showed a progressive hematologic involvement with heterogeneous hypochromic microcytic anemia, thrombocytopenia, and elevated lactic dehydrogenase. Bone marrow aspiration and biopsy were performed, which confirmed the diagnosis of B-precursor acute lymphoblastic leukemia. Hypercalcemia was resolved 72 h after the application of bisphosphonates.

Conclusion

Hypercalcemia as an oncological metabolic emergency in the onset of acute lymphoblastic leukemia is uncommon in children. The use of intravenous bisphosphonates is an effective therapy in the early resolution of the condition. We present the case of a 12-year-old patient with malignant hypercalcemia who responded favorably to the use of a single dose of bisphosphonates.

Hypercalcaemia secondary to ectopic parathyroid hormone expression in an adolescent with metastatic alveolar rhabdomyosarcoma

We report the case of a 14-year-old male with metastatic alveolar rhabdomyosarcoma, presenting with hypercalcaemia (3.89 mmol/l) and elevated parathyroid hormone (PTH) level (10.2 pmol/l). Imaging demonstrated extensive bony lytic damage, with "floating teeth" in the mandible. Normalisation of calcium levels and bony reformation of the mandible occurred following chemotherapy; PTH levels decreased initially but remained above normal levels. Imaging did not demonstrate any evidence of parathyroid abnormality. Tumour ectopic PTH secretion is a very rare cause of hypercalcaemia of malignancy in children. Hypercalcaemia with an elevated PTH, in the absence of parathyroid-related cause, should prompt investigation for underlying malignancy.

Two cases of humoral hypercalcemia of malignancy complicating infantile fibrosarcoma

We report two infants with infantile fibrosarcoma (IFS) complicated by severe hypercalcemia. Assessment demonstrated suppressed parathyroid hormone and 1,25-dihydroxyvitamin D levels with elevated circulating levels of parathyroid hormone related protein, indicating the diagnosis of humoral hypercalcemia of malignancy (HHM). HHM is a paraneoplastic syndrome rarely associated with pediatric malignancies. Hypercalcemia manifested clinically with neurologic symptoms and soft tissue calcium deposition and required aggressive management with intravenous fluids, diuretics, and supplemental electrolytes. Following treatment with neoadjuvant chemotherapy, serum calcium levels precipitously declined requiring calcium repletion. These cases highlight the improvement of hypercalcemia secondary to HHM following chemotherapy.