Unusual metastatic microcalcification in an IgG4-related disease detected by Tc-99m MDP SPECT/CT：a case report

Abstract

Background IgG4-related disease (IgG4RD) is a systemic disease affects nearly every organ. More than 90% of hypercalcemia is caused by primary hyperparathyroidism or malignancy, and rarely by IgG4RD. Case presentation A 60-year-old Chinese male was admitted urgently to the hospital with hypercalcemia and renal insufficiency. Tc-99m Methylene diphosphonate single photon emission computed tomography/computed tomography (Tc-99m MDP SPECT/CT) images showed a significantly increased uptake of tracer in the stomach and lung. After tracheoscopy, lymph node and renal biopsy,the final diagnosis of this case was IgG4RD. The patient's condition improved significantly after treatment with methylprednisolone, and renal function and blood calcium returned to normal. Conclusions IgG4RD combined with hypercalcemia is rare. For patients with renal insufficiency of unknown etiology with hypercalcemia, we should consider the possibility of IgG4RD on the basis of excluding primary hyperparathyroidism and tumor.Tc-99m MDP SPECT/CT examination can be timely detected metastatic calcification and contribute to appropriate treatment.