Endocrine Abstracts

JOINT1005

Introduction: Spontaneous retropharyngeal hematoma is a rare entity that can be caused, among others, by the rupture of enlarged parathyroid gland. Only about 40 cases of spontaneous parathyroid hemorrhage have been reported in the literature. Most of them were parathyroid adenomas, with only a few cases of carcinoma described. Parathyroid carcinoma is very rare disease with incidence 3-10 cases/10 million annually. Synchronous parathyroid carcinoma and thyroid carcinoma are extremely uncommon and the cause of its coexistence is unknown.

Case Report: 45 years old woman was referred to emergency for sore throat and dysphagia. She had a history of similar event two years ago, which was diagnosed as retropharyngeal hematoma, managed conservatively without further investigation (serum calcium not tested). Actual CT from 4/2024 showed a neck mass 42x36x20mm compressing and deviating the right lobe of the thyroid gland. Laboratory: calcium 2,93 mmol/l (normal range 2,15 - 2,55), PTH 35,45 pmol/l (normal range 1,3 - 7,6), thyroid function normal. Neck ultrasound showed the same mass as CT and multinodular enlarged right thyroid lobe. Resection of the cervical mass and right hemithyroidectomy were provided in 6/2024. Histopathology: parathyroid carcinoma and two papillary thyroid carcinomas (PTC) 3 and 1 mm. The left hemithyroidectomy followed in 9/2024 with finding of another PTC 3 mm. Due to the presence of two cancers genetic testing was indicated. The patient was found to have a likely pathogenic germline frameshift variant in the tumour suppressor gene POT 1 Lys384ValfsTer15 in a heterozygous state by whole-exome sequencing. It is known from the literature that loss of the tumour suppressor telomere shortening mechanism caused by autosomal dominant disruption of the POT1 gene leads to clonal population expansion and genomic instability, which predisposes to a higher risk of cancer. Molecular genetic testing of the resected cancers will follow.

Conclusion: We present a case of recurrent retropharyngeal hematoma of the parathyroid origin. The diagnosis was established after the disease relapsed two years later. Laboratory analysis of serum calcium should be considered as a part of investigation in nontraumatic cervical hemorrhage. The germline mutation in the tumour suppressor gene POT 1 in a heterozygous state predisposes to a higher risk of cancer and probably caused both parathyroid carcinoma and multifocal papillary thyroid carcinoma in this patient. Supported by Ministry of Health Czech Republic - DRO (Institute of Endocrinology - EÚ, 00023761).