Pathology Quiz Case 1

Abstract

A 66-YEAR-OLD WOMAN PRESENTED FROM AN outside institution 1 week after undergoing an aborted thyroidectomy for locally aggressive cancer of the thyroid gland. Intraoperative findings were notable for extrathyroid extension involving the right cricotracheal complex and encasement of the right recurrent laryngeal nerve, which was sacrificed. She did report childhood exposure to radiation, presumably for treatment of acne. There was no palpable residual thyroid or lateral neck disease on physical examination. Flexible fiberoptic laryngoscopy demonstrated a paretic right true vocal cord. A finecut computed tomogram of the neck demonstrated softtissue density fullness of the subglottic larynx, which was consistent with either tumor invasion of the airway or postoperative edema (Figure 1). In the operating room, a firm submucosal soft-tissue fullness was identified on endoscopy. Findings from a biopsy confirmed malignancy, showing cribriform and glandular architecture composed of squamoid, mucous, and intermediate cell types beneath an unremarkable respiratory epithelium. The patient underwent a total laryngopharyngectomy withacompletionthyroidectomy,bilateralparatrachealnode dissection,andacomprehensiverightneckdissection.Gross examination of the surgical specimen showed an infiltrative tumorarisingwithin the thyroidgland,withextension to the larynx, esophagus, and anterior strap muscles. The tumor demonstrated a complex histologic picture, with a gradual transition of 2 distinct types of cancer: a low-grade carcinomawithcribriformarchitectureandacarcinomaof papillary architecture and follicles containing brightly eosinophilic colloid material. The cribriform component of the tumor infiltrated ossified thyroid cartilage (Figure2) andanterior strapmusculature.Both thecribriformandthe papillary components showed mildly enlarged nuclei with irregular nuclear contours, nuclear grooves (Figure 3), and scattered intranuclear cytoplasmic pseudoinclusions. Metastatic foci of each tumor were present within numerous cervical lymph nodes. Immunohistochemical staining was positive for thyroid transcription factor 1 and thyroglobulin in both components of the tumor, although only amicroscopicfocusstainedpositively inthecribriformareas (Figure 3, inset). Staining showed strong positivity for p63 inthecribriformportion.StainingforKi-67andp53revealed a low degree of nuclear positivity ( 5%), consistent with a low-grade tumor. What is your diagnosis? Figure 1.