Papillary Thyroid Carcinoma With Axillary Lymph Node Metastasis

Papillary thyroid carcinoma (PTC) is typically known to be a non-aggressive form of thyroid follicular epithelial-derived cancer. It is characterized histologically by classic and variant forms. Metastases are uncommon and spread mainly via lymphatic channels to cervical lymph nodes and less commonly via hematogenous spread to lungs and bone. Axillary lymph node (ALN) metastasis is a rare sequela of disease presentation. A 59-year-old female presented for evaluation of shortness of breath and chest pain for one week. She had a longstanding history of hypothyroidism due to chronic lymphocytic thyroiditis which was stable on levothyroxine. Her physical exam revealed a firm mass on the inferior aspect of the left neck. Computed tomography (CT) angiogram ruled out pulmonary embolism but noted a superior mediastinal mass and significant left axillary and subpectoral adenopathy. Mammogram was negative for breast malignancy. Left axillary ultrasound showed a 1.1 x 1.8 x 1.9 cm enlarged lymph node. Thyroid ultrasound showed a 3 mm nodule on the left lower pole and a 3.7 x 2.9 x 2.1 cm heterogeneous and irregular mass in the left neck. Positron emission tomography/CT showed increased uptake in left lower paratracheal, left supraclavicular and axillary lymph nodes. Fine needle aspiration of the left neck mass and left ALN confirmed metastatic papillary carcinoma. She underwent total thyroidectomy, left modified neck, central neck, and left ALN dissection along with partial esophageal wall excision. Intraoperatively, she was found to have a multifocal tumor in the left thyroid lobe with the largest dimension of 1 cm. Surgical pathology noted that the primary tumor in the left thyroid was classic type of papillary carcinoma, and the metastatic tumor in the lymph nodes was of tall cell variant. I-123 thyroid uptake and scan after surgery showed low residual thyroid uptake of 0.6%. She underwent adjuvant ablation with 155 millicuries (mCi) of radioiodine (RAI or I-131) following levothyroxine withdrawal protocol. Post ablation therapy thyroid uptake and scan showed no radiotracer uptake within the thyroidectomy bed. According to the American thyroid association (ATA) risk stratification system, she was categorized as high risk. This case illustrates that PTC may exceptionally spread to axillary lymph nodes. Physiologic flow is centripetal to the jugulosubclavian junction and there is no communication between cervical and axillary lymphatics. However malignant tumors can alter and partially block lymphatic pathways, resulting in ALN metastasis in a retrograde direction. This case also demonstrates that PTC can be transformed into aggressive forms associated with worse prognosis such as tall cell variant. Further comprehensive monitoring and management approaches are needed to plan treatment and gauge prognosis of patients with PTC who present with ALN metastasis.