JTO Clinical and Research Reports (Aug 2021)

Hypercalcemia Owing to Overproduction of 1,25-Dihydroxyvitamin D3 in Fetal Lung Adenocarcinoma: Case Report

  • Tomohito Saito, MD, PhD,
  • Mistuaki Ishida, MD, PhD,
  • Makiko Kusabe, MD,
  • Takahiro Utsumi, MD,
  • Natsumi Maru, MD,
  • Hiroshi Matsui, MD,
  • Yohei Taniguchi, MD, PhD,
  • Takayasu Kurata, MD, PhD,
  • Hiroaki Kurokawa, MD, PhD,
  • Takanobu Imada, MD, PhD,
  • Koji Tsuta, MD, PhD,
  • Hiroyasu Tsukaguchi, MD, PhD,
  • Tomohiro Murakawa, MD, PhD

Journal volume & issue
Vol. 2, no. 8
p. 100204

Abstract

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Hypercalcemia is a common electrolyte abnormality in malignancy and is largely caused by activation of parathyroid hormone (PTH) pathways. We report the case of a 76-year-old man with hypercalcemia primarily owing to 1,25-dihydroxyvitamin D3 overproduction from a high-grade fetal lung adenocarcinoma. Histologically, the tumor itself and tumor-adjacent macrophages were positive for the CYP27B1 protein, a key enzyme that generates 1,25-dihydroxyvitamin D3. Suppression was observed in serum PTH and PTH-related hormone levels, suggesting hypercalcemia is independent of the PTH pathway. Serum calcium level returned to normal after surgical resection of the lung cancer, supporting extrarenal overproduction of 1,25-dihydroxyvitamin D3 elicited by the tumors is the cause of hypercalcemia in this patient.

Keywords