Thyrotoxicosis With Medullary Thyroid Carcinoma: A Rare Endocrine Diagnostic Challenge

TL;DR

A rare case of medullary thyroid cancer presenting as hyperthyroidism is reported, highlighting the diagnostic challenge it poses.

Contribution

This case adds to the limited literature on medullary thyroid carcinoma presenting as thyrotoxicosis.

Findings

A 56-year-old female presented with hyperthyroidism symptoms but was diagnosed with medullary thyroid carcinoma.

Imaging and FNAC confirmed the presence of high-grade thyroid cancer with lymph node involvement.

Surgical intervention resolved the patient's symptoms and she remained well at follow-up.

Abstract

The incidence of a hyper-functioning thyroid gland presenting alongside an underlying malignancy rarely occurs. Herein, we present a rare case of a 56-year-old female patient presenting with features of hyperthyroidism only to be later diagnosed with an underlying malignancy, medullary thyroid carcinoma (MTC). Ultrasonography (USG) of the neck revealed a suspicious nodule with microcalcifications in the right lobe of the thyroid. Subsequent CT imaging of the neck indicated possible cervical and mediastinal lymph node involvement. Fine-needle aspiration cytology (FNAC) confirmed the presence of high-grade thyroid carcinoma. The patient underwent total thyroidectomy with neck node dissection after which her symptoms subsided. She was well at her last follow-up.

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