Mucoepidermoid carcinoma is the most common malignant salivary gland tumor in the oral cavity. Primary thyroid involvement is rare, with few cases in the literature. The clinical case describes a patient with squamous cell carcinoma in the hard palate submitted to maxillectomy and lymphadenectomy. Invasion of the thyroid was observed during the surgery, so it was complemented with thyroidectomy. The histopathology resulted in squamous cell carcinoma of the palate with maxillary invasion, papillary carcinoma of the thyroid in the left lobe and mucoepidermoid carcinoma of the thyroid in the right lobe. Mucoepidermoid carcinoma has been found in association with other glandular epithelia of the head and neck.

Objective: Initial diagnosis of medullary thyroid carcinoma (MTC) is frequently associated with advanced stages and a poor prognosis. Thus, the need for earlier diagnoses and detection in relatives at risk for the disease has led to increased use of RET genetic screening. Subjects and methods: We performed RET screening in 247 subjects who were referred to the Brazilian Research Consortium for Multiple Endocrine Neoplasia (BRASMEN) Center in the State of Ceará. Direct genetic sequencing was used to analyze exons 8, 10, 11, and 13-16 in MTC index cases and specific exons in at risk relatives. Afterward, clinical follow-up was offered to all the patients with MTC and their affected relatives. Results: RET screening was performed in 60 MTC index patients and 187 at-risk family members. At the initial clinical assessment of the index patients, 54 (90%) were diagnosed with apparently sporadic disease and 6 (10%) diagnosed with hereditary disease. After RET screening, we found that 31 (52%) index patients had sporadic disease, and 29 (48%) had hereditary disease. Regarding at-risk relatives, 73/187 were mutation carriers. Mutations in RET codon 804 and the rare p.M918V mutation were the most prevalent. Conclusions: Performing RET screening in Ceará allowed us to identify a different mutation profile in this region compared with other areas. RET screening also enabled the diagnosis of a significant number of hereditary MTC patients who were initially classified as sporadic disease patients and benefited their relatives, who were unaware of the risks and the consequences of bearing a RET mutation.