Diagnostic and therapeutic implications of asymptomatic parathyroid adenoma co-existing with papillary thyroid carcinoma; a rare case report

Abstract

Asymptomatic parathyroid adenoma (PA) co-existing with a papillary thyroid carcinoma (PTC) is rare. Pre-operative diagnosis of the PA based on routine investigations is challenging. Ultrasound is a poor diagnostic tool for central compartment evaluation and pre-operative serum calcium estimation is not routinely performed in non-medullary thyroid cancers (NMTCs). Intra-operatively a PA can mimic a metastatic central compartment node. A 28 years old lady presented with a large right sided thyroid nodule with no other associated symptoms which was diagnosed as PTC on fine needle aspiration cytology (FNAC). Ultrasound did not reveal any suspicious central compartment lymph nodes. Intra-operatively, a right sided central compartment nodule separate from the thyroid gland was found. The lesion clinically mimicked a metastatic node based on which central compartment nodal clearance was performed. All parathyroids except the right superior parathyroid (which could not be identified intra-operatively) were preserved. Postoperatively, she developed severe transient hypocalcemia. The suspicious metastatic node on histopathology was incidentally found to be a PA. An asymptomatic PA can rarely co-exist with a non-medullary thyroid carcinoma (NMTC) and we recommend pre-operative routine serum calcium evaluation and intra-operative frozen section of suspicious central compartment nodes to preempt and diagnose such associations.

Keywords: Asymptomatic parathyroid adenoma, Papillary thyroid carcinoma, Hypocalcemia, Non-medullary thyroid carcinoma