Spindle cell variant of medullary thyroid carcinoma: a clinicopathologic study of four cases

Medullary thyroid carcinoma

INTRODUCTION

Medullary thyroid carcinoma (MTC) constitutes approximately 5-10% of all thyroid cancers. Although the tumor forms in the thyroid, it doesn't originate from thyroid cells, but from the C cells or parafollicular cells which produce and release a hormone called calcitonin (CT). Starting from the second half of the 1900s, MTC was progressively studied and defined.

AREAS COVERED

This study aims to analyze the history, clinical presentation and biological behavior of MTC, bio-humoral and instrumental diagnosis, molecular profiling, genetic screening, preoperative staging and instrumental procedures, indispensable in expert and dedicated hands, such as high-resolution ultrasonography, CT-scan, MRI and PET/TC. We examine recommended and controversial surgical indications and procedures, prophylactic early surgery and multiple endocrine neoplasia surgery. Also, we discuss pathological anatomy classification and targeted therapies. The role of serum CT is valued both as undisputed and constant preoperative diagnostic marker, obscuring cytology and as early postoperative marker that predicts disease persistence.

EXPERT OPINION

With a complete preoperative study, unnecessary or useless, late and extended interventions can be reduced in favor of tailored surgery that also considers quality of life. Finally, great progress has been made in targeted therapy, with favorable impact on survival.

Extensive spindling in medullary thyroid carcinoma posing a diagnostic challenge: A case report

Medullary thyroid carcinoma is a neuroendocrine tumor derived from parafollicular or 'C' cells with sporadic and familial forms. Fine needle aspiration cytology is a quick way to establish the diagnosis. Sometimes a usual tumor may show prominent spindling on cytomorphology due to sampling issues, which poses a diagnostic challenge. When encountering spindled tumor cells on cytology smears from the thyroid, differential diagnoses encompass many benign and malignant lesions. We present cytological findings of the usual type of medullary thyroid carcinoma showing extensive spindling on cytology smears, which was a diagnostic dilemma. An accurate diagnosis was reached with the judicious use of immunocytochemistry on the cell block. We also discuss the available literature, differential diagnoses, and how to troubleshoot.