Zoledronate-responsive calcitriol-mediated hypercalcemia in a 5-year-old case with squamous cell carcinoma on the background of xeroderma pigmentosum

Ectopic parathyroid hormone as a rare aetiology of hypercalcemia with rhabdomyosarcoma: a new treatment strategy with zoledronic acid and Denosumab

OBJECTIVES

Ectopic parathyroid hormone (PTH) secretion is rare in children with rhabdomyosarcoma, and only a few pediatric cases have been reported to date. Reports of the use of zoledronic acid (ZA) and Denosumab are limited for the treatment of hypercalcemia of malignancy (HCM) in the pediatric population. The aim of presenting this pediatric case of rhabdomyosarcoma accompanied by HCM, secondary to ectopic PTH secretion, was to highlight the benefits of ZA as a first-choice bisphosphonate in this situation with Denosumab as an alternative therapy.

CASE PRESENTATION

The patient was diagnosed at 13 years with alveolar rhabdomyosarcoma. Multiple bone metastases first appeared at 15 years, but he remained normocalcemic until 17 years old when serum calcium was 15.1 mg/dL and PTH 249 pg/mL. While serum calcium responded well after ZA and Denosumab cycles, PTH remained elevated, reaching a peak value of 1851 pg/mL during treatment cycles.

CONCLUSIONS

We report a patient with rhabdomyosarcoma accompanied by HCM, secondary to ectopic PTH, in whom the HCM was successfully managed with ZA and Denosumab. We believe that ZA should be the bisphosphonate of choice in pediatric HCM with rhabdomyosarcoma, while Denosumab may be another option in ZA-refractory cases.

Hypercalcemia of malignancy in metastatic esophageal squamous cell carcinoma with simultaneous PTHrP and calcitriol overproduction: A case report with literature review

Introduction and importance

hypercalcemia of malignancy is a severe complication of malignancy and associated with poor prognosis. Four mechanisms are implicated in this metabolic disorder, including excess parathyroid-related peptide secretion, focal osteolysis secondary to bone metastasis or multiple myeloma, excess calcitriol production, and ectopic parathyroid hormone production. Humoral hypercalcemia of malignancy secondary to isolated PTHrP or calcitriol overproduction is known; however, hypercalcemia of malignancy due to simultaneous PTHrP and calcitriol overproduction is less well known.

Case presentation

we report a case of a 63-year-old male who was diagnosed with poorly differentiated esophageal squamous cell carcinoma with simultaneous PTHrP and calcitriol overproduction.

Clinical discussion

while hypercalcemia of malignancy secondary to simultaneous PTHrP and calcitriol secretion has been reported in other solid cancers, this is the first case of humoral hypercalcemia of malignancy secondary to simultaneous PTHrP and calcitriol secretion associated with esophageal cancer. This phenomenon deserves increased recognition as it has both diagnostic and therapeutic consequences. We discuss the current testing algorithm and its limitations in determining the etiology of hypercalcemia of malignancy since it may miss the diagnosis of simultaneous PTHrP and calcitriol production.

Conclusion

we propose a revised testing algorithm for hypercalcemia of malignancy, which may improve the identification of simultaneous overproduction of PTHrP and calcitriol. This new algorithm can better characterize the mechanisms of hypercalcemia of malignancy and more appropriately guide treatment.

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Hypercalcemia of malignancy with simultaneous PTHrP and calcitriol production merits better recognition for both diagnostic and therapeutic purposes.

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A case of hypercalcemia of metastatic esophageal squamous cell carcinoma with simultaneous PTHrP and calcitriol is reported.

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The current testing algorithm and its limitations of hypercalcemia of malignancy is discussed, and a revised one is proposed.