Parathyroid carcinoma during pregnancy: a novel pathogenic CDC73 mutation - a case report

Parathyroid carcinoma is an uncommon cause of PTH-dependent hypercalcemia. Only a handful of cases have been reported of parathyroid carcinoma during pregnancy.

Twenty-four - Year - old female presented with proximal myopathy was found to have hypercalcemia. Her serum corrected total calcium was - 15 mg/dl (8.5 - 10.3), serum phosphate - 2.3 mg/dl (2.5 - 4.5), intact PTH - 118 pg/ml (20 - 80), Vitamin D - 15 ng/ml and Urine Ca/Cr ratio - 2.1 (0.1 - 0.2). Her CECT-neck revealed a well-defined mass lesion posterior to the right lobe of the thyroid - 2.6 cm × 2.5 cm × 2.9 cm in size. She was started on vitamin D supplementation, and she underwent right lower focal parathyroidectomy. Her PTH levels normalized following surgery. Her histology revealed an atypical parathyroid adenoma. She was treated with calcium and vitamin D. Her follow up was uneventful. One year following initial surgery the patient became pregnant and at 16 weeks of POA, the patient presented with a rapidly enhancing neck mass for one week duration. Her biochemical investigations were suggestive of a recurrence of primary hyperparathyroidism. Her ultrasound scan of the neck revealed a well-defined discreate hypoechoic nodule, superior to the thyroid isthmus which was confirmed by a non-contrast MRI scan of the neck. She underwent an uncomplicated second trimester parathyroid tumour excision with normalization of post op PTH. Her histology revealed a parathyroid carcinoma with vascular and capsular invasion. Her genetic studies revealed a novel frameshift mutation of the CDC73 gene. She was treated with calcium and vitamin D supplementation and closely followed up with ionized calcium and PTH levels which were normal throughout the pregnancy. She had an uncomplicated caesarean section at a POA of 37 weeks. Currently she is twelve weeks post-partum, in remission of disease.

This case shows the importance of stringent follow up of atypical parathyroid adenoma patients, the benefit of second trimester surgery in management of hypercalcemia due to parathyroid carcinoma during pregnancy and the importance of identifying the novel CDC73 gene mutation.