Endocrine Abstracts

Parathyroid carcinoma is a very rare cause of primary hyperparathyroidism (<1% of cases). Spontaneous intralesional haemorrhage is exceptionally uncommon but may present as a life-threatening neck emergency. We describe a diagnostically and therapeutically complex case of functioning parathyroid carcinoma complicated by spontaneous haemorrhage and refractory hypercalcaemia. A 67-year-old man with hypertension, chronic kidney disease and bladder calculus was diagnosed with primary hyperparathyroidism in August 2024. By November, renal imaging was normal, DEXA confirmed osteoporosis, and he was referred for surgery. Calcium rose to 3.42 mmol/l (2.2–2.6), prompting cinacalcet 30 mg twice daily, later 60 mg twice daily. In January 2025 he presented with abdominal pain, fatigue and reduced oral intake; corrected calcium 4.27 mmol/l, PTH 111 pmol/l (1.6–6.9), eGFR 55 mL/min. On day two, he developed suprasternal ecchymosis and neck swelling. CT neck showed a large 6.7 cm right inferior parathyroid lesion with intralesional haemorrhage and oedema. MDT initially advised conservative management due to high surgical risk in acute bleeding. Despite hydration and cinacalcet 60 mg tds, calcium remained >3.0 mmol/l, requiring repeated intravenous bisphosphonates. Repeat imaging confirmed a persistent lesion with mediastinal extension. He underwent right parathyroidectomy and ipsilateral hemithyroidectomy; intra-operative PTH fell from 157 to 1.2 pmol/l. Post-operatively he developed a cervical haematoma requiring evacuation. Histology showed T1 N0 M0 R1 low-grade parathyroid carcinoma (Ki-67 <1%), positive for CK7, GATA3, chromogranin and vimentin; genetic testing was negative. Follow-up showed calcium 2.44 mmol/l, PTH 17 pmol/l (mildly raised, felt CKD-related), recovery of vocal cord function and no recurrence on imaging. This case highlights spontaneous haemorrhage as a rare presentation of parathyroid carcinoma. Severe hypercalcaemia, very high PTH and poor medical response should prompt malignancy consideration. Early imaging, airway assessment, MDT coordination and surgery are vital, with long-term surveillance recommended.