Diffuse Follicular Variant of Papillary Thyroid Carcinoma in a 69-Year-old Man with Extensive Extrathyroidal Extension: A Case Report
A 69-yr-old man was referred to our institution for the management of his neck mass. He has visited the previous hospital on February 17, 2011 with hoarseness for a few months. He had anti-reflux medication, but the hoarseness got worse. He was medicated for hypertension, and no other past history was found. The physical examination on him revealed firm, fixed mass on left anterior neck and limited motility of the vocal cord was observed. By further evaluation with computed tomography scan, a huge, ill-marginated mass was found, invading the left thyroid lobe and isthmus (). Tracheal and esophageal invasion was suggested. Multiple enlarged lymph nodes were present in the left neck. At previous hospital, fine-needle aspiration was done to the mass in the left thyroid and left neck nodes, diagnosed as papillary thyroid carcinoma with lymph node metastases. In our institution, the aspiration cytology slides of thyroid and lymph nodes were reviewed, and also the diagnosis of papillary thyroid carcinoma with lymph node metastases was rendered.\nAfter referred to our institution, he received bilateral total thyroidectomy with central compartment neck node dissection. After 17 days from the operation, the patient expired due to asphyxia caused by an unexplained bleeding in the gastrointestinal tract.\nOn examination of resected specimen, pathologic diagnosis of diffuse follicular variant papillary thyroid carcinoma (DFVPTC) was rendered. Multiple carcinomas were found in both thyroids, infiltrating into the esophagus, trachea, sternum, and mandible with multiple metastases in the regional lymph nodes.\nThe specimen was consisted of entire thyroid (total weight: 29.8 g, right lobe: 3.5 × 3.8 × 1 cm, left: 6 × 4 × 2.3 cm) with regional lymph nodes, and multiple biopsies from tracheal, esophageal, sternum, mandibular area. Left thyroid was firm and fibrotic in consistency. Sectioned surface showed poorly marginated yellowish and fibrotic tumor (3.7 cm), which was infiltrative and totally replacing the entire lobe (). Right lobe seemed to be grossly normal, but a 0.9 cm-sized vague nodule was found in lower pole on sectioning.\nHematoxylin-eosin (HE) stain revealed diffuse, vaguely nodular tumor in left thyroid (). The tumor showed micro- and macrofollicular growth pattern, which was infiltrating into the thyroid parenchyma, extrathyroidal skeletal muscle and fibroadipose tissue. Dense collagenous fibrosis was accompanied by tumor cells (). Inflammation was rarely found. Cytologically, each of tumor cells revealed vesicular nuclei with nuclear clearing and grooves, which are histologic findings of papillary thyroid carcinoma (PTC) (). The other histologic features, such as intranuclear pseudoinclusion, psammomatous calcification, or discrete papillary structure were rarely seen.\nSix of 60 lymph nodes metastases were found from neck dissection, of which the largest size was 2.2 cm. Metastatic carcinoma in lymph nodes showed same histologic features as in the thyroid, like micro-and macrofollicular growth pattern of tumor cells harboring nuclear features of PTC (). Permeating tumor cells were found in separately sent esophagus and tracheal cartilage, which also exhibited the same histologic features as in the thyroid ().\nFor ancillary interest, several immunohistochemical stainings - galectin-3, cytokeratin (CK) 19, CD56, thyroglobulin, Ki67, p53 - were performed on the left thyroid. Diffuse positive for galectin-3, CK19, and negative for CD56 were seen in tumor area, which was vice versa in normal thyroid tissue (). Tumor showed decreased stain intensity for thyroglobulin than normal thyroid tissue (). Ki67 labeled tumor cells were about 5% (found up to 37/high power field) and p53 nuclear expression was about 10% of tumor cells. Additionally, BRAF point mutation (V600E) was detected by sequencing anaylsis.