Parathyroid Carcinoma Mimicking Thyroid Hyalinizing Trabecular Tumor: A Case Report and Review of Atypical Presentations of Parathyroid Carcinoma.

We present a parathyroid carcinoma with hyalinizing trabecular architecture and a prominent spindle-cell component. The tumor closely mimicked a hyalinizing trabecular tumor of the thyroid due to its trabecular growth, eosinophilic hyalinized stroma, and nuclear features including grooves and intranuclear pseudoinclusions. Recognition of this rare pattern is important to avoid misclassification.