Aberrant intrathyroidal lymph node metastasis in classical papillary thyroid carcinoma

Background In cases of papillary thyroid carcinoma (PTC), lymph nodes are a typical site of metastasis. Extrathyroidal tissue involvement in differentiated thyroid carcinoma causes the disease to progress and affects the patients’ treatment options. Papillary thyroid carcinoma (PTC) is the common type in differentiated thyroid carcinoma (DTC), the other type is follicular thyroid carcinoma (FTC). Ectopic sites, such as intrathyroidal lymph node invasion in classical papillary thyroid malignancy, are extremely uncommon. It can be difficult to detect an intrathyroidal lymph node (ITLN) during a histopathological test, but it is important to do so since it affects the stage of the disease and subsequent treatment. Case presentation We present the case of a 63-year-old woman who presented with multinodular goitre and underwent total thyroidectomy. She was diagnosed with aberrant intrathyroidal lymph node metastases during pathological testing, resulting in an upgrade in treatment. Owing to the exceptionally unusual ectopic position of lymph node metastasis, in this case, there is a risk of diagnostic and therapeutic misinterpretation. This patient was treated with high-dose radioactive iodine in view of lymph node metastases. Conclusions Identification of ITLN by imaging characteristics is sometimes difficult, being often an intraoperative discovery and histopathological correlation that lead to upstage the disease and alter the final management.