Parathyroid Carcinoma

This is a rare and unusual entity. It accounts for about 1% of cases of primary hyperparathyroidism.

Indicators of parathyroid cancers
1) Severe hypercalcaemia (>3.5 mmol/L or >16 mg/dl)
2) Signs of gross invasion of surrounding structures
3) Palpable neck mass
4) Symptomatic renal and bone disease
5) Distant metastasis

Diagnosis
• Not generally made on histology as capsular infiltration may also be seen in adenomas
• Triad for diagnosis of parathyroid carcinoma is
– Recurrence after surgery
– Distant metastasis
– Invasion of adjacent structures

Management
En bloc surgical resection of the carcinoma with ipsilateral thyroidectomy. Ipsilateral thyroidectomy recommended to avoid spillage of tumour as recurrence high if this occurs.

Recurrence Pattern:
• The rate of recurrent disease after initial en bloc resection is between 40 and 70%
• Patients generally present with recurrent hypercalcaemia and death is generally due to complications of hypercalcaemia rather than distant metastasis. Hence aggressive re-surgery is warranted if feasible.
• Chemotherapy and irradiation do not have much benefit.

Survival:
Five-year survival: 40% and 69%.