Endocrine Abstracts

JOINT155

Papillary thyroid carcinoma (PTC) is the most common histological type of thyroid cancer. Its spread is mainly lymphatic. Distant metastases are rare and most often affect the lungs, liver and bones. Despite the anatomical proximity of the parotid gland, metastases at its level are extremely rare. The revelation of a PTC by a metastasis of this region remains exceptional.

Observation: 57-year-old patient, with no significant history, presenting with a latero-cervical swelling that had been developing for 3 years. Cervical CT scan revealed a right subparotid mass originating from the right sternocleidomastoid muscle, infiltrating the lower pole of the homolateral parotid. The patient underwent resection of the tumor mass and adenopathy of territory IIa, in addition to a right exofacial parotidectomy. The anatomical-pathological and immunohistochemical analysis was in favor of a parotid and lymph node localization of a CPT. The patient was subsequently referred to our training for further management. The cervical examination was normal, without nodules or adenopathies. The cervical ultrasound revealed a small thyroid. Given the anatomopathological result of the initial surgery, a total thyroidectomy with bilateral recurrent and jugulo-carotid lymph node dissection was indicated and performed. The anatomo-pathological study showed two foci of invasive papillary carcinoma of 2 mm and 7 mm in long axis with the presence of 37N-/37N reactive lymph nodes. The CPT was classified as: pT1aN1bM1.

Discussion: Papillary thyroid carcinoma is the most common type of well-differentiated thyroid cancer. It is usually revealed by a thyroid nodule. Local and distant metastases of classic papillary thyroid carcinoma occur mainly in regional lymph nodes, lungs, and bones. Parotid involvement in PTC is unusual, and especially as the first presentation of the disease and rarely reported in the literature. Treatment is mainly based on surgery and radiation therapy, with recourse to chemo-radiotherapy in certain situations

Conclusions: The revelation of papillary thyroid carcinoma by a parotid metastasis constitutes the particularity of our case. Metastasis to parotid gland from thyroid origin, seems to be an indication of aggressive disease. Therapeutic management in this type of situation is based on surgery with the addition of adjuvant iratherapy and then hormone therapy at a restraining dose.