Poorly differentiated thyroid carcinoma arising from substernal goiter: a case report

Introduction and importance:

Poorly differentiated thyroid carcinomas represent a rare heterogeneous group of malignant tumors that constitute approximately 2-4% of all thyroid neoplasms. Substernal Goiter is defined as an enlargement of the thyroid gland that is located below the thoracic inlet. Malignant neoplasms arising from a substernal goiter were reported in only 2-3% of cases.

This case report has been reported in line with the SCARE Criteria.

Case presentation:

This article presents a 54-year-old Syrian female who presented at our institution due to dysphagia, dyspnea, cervical swelling, and loss of appetite. Following clinical and radiological examinations, total thyroidectomy with lymph node dissection was performed. Microscopic examination revealed an infiltrative growth pattern of insular, trabecular, and solid formations of epithelial cells with scant eosinophilic cytoplasm, hyperchromatic nuclei, and bizarre mitotic figures with areas of necrosis. Subsequently, the final diagnosis was confirmed as a multifocal poorly differentiated thyroid carcinoma arising from a substernal goiter.

Clinical discussion:

The heterogeneity of histologic features of poorly differentiated thyroid carcinoma represents a diagnostic challenge. Diagnosis of poorly differentiated thyroid carcinomas is based on the Turin Criteria which highlights histopathological features. Computed tomography plays a major role in substernal goiter for further evaluation.

Conclusion:

In this manuscript, we aimed to present a unique case report with challenging diagnostic features including the rapid development of an infiltrative poorly differentiated thyroid carcinoma from a substernal goiter highlighting the importance of a detailed histopathological examination of thyroid nodules in the absence of significant medical history.