Two Rare Cases of Metastatic Occult Thyroid Carcinoma Without Primary Cancer in the Thyroid Gland

Papillary thyroid cancer (PTC) contributes to the majority of all thyroid malignancies. In this case report, we detail two cases of occult thyroid carcinoma (OTC), which presents with thyroid metastasis to locoregional lymph nodes without having an initial primary tumor detected in the thyroid gland. OTC may be found incidentally on biopsy, surgery, or imaging. Advancements in diagnostic technology have allowed physicians to identify and treat OTC at an earlier stage. We present two patients who were found to have metastases to cervical lymph nodes without a primary identification in the thyroid gland. The first patient was a 67-year-old female who noticed an enlarging mass in her right neck at levels III and IV. Fine needle aspiration (FNA) revealed the presence of PTC. The patient underwent a total thyroidectomy, central nodal dissection, and right-modified radical neck dissection. Final pathology confirmed the presence of PTC metastasis to cervical lymph nodes, but no primary tumor was identified within the thyroid gland. The second patient was a 79-year-old male who presented with a painless mass of the left parotid gland. The FNA of the patient revealed PTC metastasis to his left parotid gland. The patient underwent a total thyroidectomy, ipsilateral central nodal dissection, ipsilateral modified radical neck dissection, and inferior superficial and deep lobe parotidectomy. No malignancy was detected within the thyroid gland or central or lateral neck lymph nodes on final pathology. Carcinoma was confined to an intra-parotid node in the deep lobe of the parotid gland. OTC is a rare phenomenon in PTC. One proposed theory for OTC includes spontaneous regression of the primary tumor and genetic mutations to the BRAF gene. Due to the fact that it is easy for this rare condition to be misdiagnosed, more studies should be conducted to standardize diagnostic and treatment plans for OTC.