Pericardial Type 1 Parathyromatosis: A very rare cause of primary hyperparathyroidism.

Background: Parathyromatosis is a rare clinical condition where hyperfunctioning parathyroid tissue is scattered in the neck and the mediastinum. It is difficult to diagnose and manage due to recurrent or persistent hyperparathyroidism.

Case Report: We present a peculiar case of hyperparathyroidism as the parathyroid tissue was in unusual location. Scintigraphy done revealed a lesion suspicious for ectopic parathyroid tissue in the retrosternum in a 58 years old female patient with primary hyperparathyroidism. No pathologic lesions were found on neck exploration, subsequently, sternotomy was performed and suspicious lesion removed but microscopic evaluation of the frozen section found no parathyroid tissue in the resected specimen. A decision to perform thymectomy and total resection of pericardial fatty tissue was made. Final histopathology revealed parathyromatosis and confirmed the first case of pericardial type 1 parathyromatosis.

Conclusion: Long-term remission is rare in these patients, sometimes needing medical treatment and multiple surgeries. In this patient, there was no recurrence during the four years follow-up. In patients with no history of neck surgery, primary parathyromatosis should be considered in the differential diagnosis of hyperparathyroidism.