Diagnostic Challenges of Medullary Thyroid Carcinoma

Abstract

<b><i>Background:</i></b> Medullary thyroid carcinoma (MTC) comprises 1–2% of all thyroid cancers, yet 15% of all thyroid cancer-related deaths. While up to 20% of cases may be predicted due to autosomal dominant germline mutations, 80% of cases are sporadic. However, due to non-specific presenting symptoms and diagnostic imaging, prompt diagnosis and treatment has remained elusive. This article will further investigate the limitations of MTC diagnosis and look into future areas for diagnostic improvement. <b><i>Methods:</i></b> Relevant articles were identified using a systematic PubMed and Google Scholar search. <b><i>Results:</i></b> Prophylactic total thyroidectomy for the 20% of MTC cases that are present in autosomal dominant disorder provides definitive treatment. Serum calcitonin (Ctn) screening has several technical limitations due to population variability and laboratory assay interference, but advances in laboratory technology and combined use with fine needle aspiration increase its sensitivity. Other serum assays such as carcinoembryonic antigen and procalcitonin have limited applicability. Thyroid ultrasound remains the gold standard for the initial diagnostic planning, with limited application for CT, MRI, and PET imaging. <b><i>Conclusion:</i></b> With complete surgical resection the only definitive treatment, early MTC diagnosis has presented an elusive challenge, mainly due to its relative rarity and difficulty in finding an economic screening strategy. Careful family history combined with fine needle aspiration with serum Ctn analysis can improve diagnostic sensitivity and specificity to greater than 95%.

Update on the Diagnosis and Management of Medullary Thyroid Cancer: What Has Changed in Recent Years?

“…In addition, diarrhea, flushing and chest pain are sometimes observed. Recurrent respiratory infections may be associated with advanced disease [ 6 , 7 ].…”

“…MTC is a rare cancer. Depending on the source, MTC is reported to account for only 1% to 4% of thyroid cancer cases; however, MTC accounts for up to 15% of related deaths [ 5 , 6 ]. Of all MTCs, approximately 25% are familial, and 75% are sporadic [ 11 ].…”

“…The sample is cytologically evaluated as part of the standard diagnostic procedure. The histological features of MTCs are salt-and-pepper chromatin, multinucleation and the presence of solid nests of plasmacytoid or spindled cells in a fibrous stroma [ 6 , 15 , 27 ]. However, the cytological picture can be highly variable.…”

“…Microscopic MTC tends to be more cohesive and may not have either plasmacytoid or spindled cells. According to recent publications, the sensitivity of FNA biopsy sample analysis can reach up to 86% [ 6 ]. Therefore, relying on cytological examination may result in misdiagnosis.…”

Prognosis of radiotherapy in medullary thyroid carcinoma patients without distant metastasis

“…About 80% of MTC occurs in sporadic form and 20% occurs in genetic form. And hereditary MTC may be predicted due to germline mutations of the RET protooncogene ( 3 , 4 ).…”