# Papillary Thyroid Carcinoma Infiltrating a Parathyroid Adenoma: A Case Report

## TL;DR

A rare case of papillary thyroid cancer invading a parathyroid adenoma is reported, highlighting the potential for these conditions to coexist and complicate treatment.

## Contribution

This case report presents a rare histological interaction between papillary thyroid carcinoma and parathyroid adenoma.

## Key findings

- The patient had concurrent parathyroid adenoma and papillary thyroid carcinoma.
- Histology confirmed direct invasion of the parathyroid adenoma by the thyroid carcinoma.
- Surgery resolved hypercalcemia and symptoms, with postoperative hormone normalization.

## Abstract

Primary hyperparathyroidism due to parathyroid adenoma with concurrent papillary thyroid carcinoma is rare. Less frequently described is the histological interplay between these pathologies. This report describes the case of a 70-year-old female patient who presented with symptomatic hypercalcemia. Subsequent imaging was indicative of a left inferior lobe parathyroid adenoma and highly suspicious for left inferior lobe thyroid carcinoma. A subtotal thyroidectomy with isolated parathyroidectomy was performed. Postoperatively, the patient demonstrated normalization of calcium levels, parathyroid hormone, and resolution of symptoms. Histological evaluation demonstrated direct parathyroid adenoma invasion by the papillary thyroid carcinoma. This report demonstrates that although rare, parathyroid adenoma and papillary thyroid carcinoma can coexist and have the potential to complicate management.