Contributed by Joel F. Gradowski, MD and E. Leon Barnes Jr, MD
Published on line in May 2006
A 69-year-old man presented with a left neck mass. The patient underwent total thyroidectomy, central compartment neck dissection, sternocleidomastoid muscle flap reconstruction, and primary closure of the esophageal wall. The total thyroidectomy specimen was irregular in shape, the right lobe measured 4.5 x 2.0 x 1.5 cm and the left lobe measures 9.0 x 5.5 x 4.5 cm. The exterior surface of the gland was tan-pink and rubbery. The cut surface of the left lobe revealed a 7.5 x 4.5 cm tan-grey lesion. The lesion approached to within less than 1mm of the capsular surface. Scant normal appearing thyroid parenchyma was present at the superior aspect of the left lobe. The right lobe parenchyma was red and beefy.
Image-2: Low power (The majority of the tumor)
Image-3: Low power (5% of the tumor)
Image-4: High Power
Image-5: Angiolymphatic Invasion
Gross Findings: The total thyroidectomy was asymmetric. The right lobe measured 4.5 x 2.0 x 1.5 cm and the left lobe measures 9.0 x 5.5 x 4.5 cm. The cut surface of the left lobe revealed a 7.5 x 4.5 cm tan-grey lesion, which occupied almost the entire lobe coming within 1mm of the capsular surface. The right lobe was red and beefy. Two calcified nodules, 1.0 and 0.3cm respectively, were identified in the right lobe.
Light Microscopy: The tumor was primarily composed of large sheets and chords of polygonal cells with abundant granular eosinophilic cytoplasm and eosinophilic intranuclear inclusions. The nuclei were eccentric with two to three prominent nucleoli. Occasional cells with pleomorphic nuclei were observed. The rhabdoid cells comprised 95% of the sampled tumor. Mitotic figures were infrequent, however necrosis was readily identified. Angiolymphatic and perineural invasion were identified. The rhabdoid cells extended through the thyroid capsule into the perithyroidal soft tissue and involved the surgical margin of resection. A small area of conventional papillary thyroid carcinoma was identified, comprising 5% of the sampled tumor. Metastatic papillary thyroid carcinoma was identified on one of three lymph nodes. Four hypercellular parathyroid glands were also identified.
Immunohistochemistry: The rhabdoid cells showed strong reactivity for vimentin and S100 protein and showed focal expression of cytokeratin 7, CAM 5.2, cytokeratin 19, and pancytokeratin. Ki-67 demonstrated a high proliferative rate in the rhabdoid cells. The rhabdoid cells did not express calcitonin, CEA, cytokeratin 20, tyrosinase, myoglobin, HHF35, myogenin, smooth muscle actin, synaptophysin, chromogranin, E-cadherin, thyroglobulin, or TTF1. The papillary carcinoma expressed the same cytokeratin profile as well as reactivity for thyroglobulin, TTF1, and E-cadherin.