Clinicopathological Features of Thyroid-Like Low-Grade Nasopharyngeal Papillary Adenocarcinoma: A Case Report and Review of the Literature

Abstract

Thyroid-like low-grade nasopharyngeal papillary adenocarcinoma (TL-LGNPPA) is an extremely rare neoplasm of the nasopharynx. Accordingly, its clinical and pathological characteristics are not well-known. We report a case of TL-LGNPPA and review the relevant literature on TL-LGNPPA. A 38-year-old Japanese woman presented with a history of nasal obstruction that had persisted for 1 month after symptoms of a common cold (e.g., low-grade fever, sore throat, and fatigue). A pedunculated tumor of ∼20 mm in diameter was found on the posterior edge of the nasal septum. The tumor was endoscopically resected. Based on careful histopathological and immunohistochemical examinations, it was diagnosed as TL-LGNPPA. At 5 years after surgery, the patient remained disease-free. TL-LGNPPA has a very good prognosis, and complete resection with a sufficient safety margin is recommended as the first-line treatment. The morphological characteristics and immunohistochemical findings, especially TTF-1 positivity and thyroglobulin negativity, are important for the diagnosis.

Thyroid-like low-grade nasopharyngeal papillary adenocarcinoma with squamous differentiation in the posterior nasal septum

“…Most TL-LGNPPAs have a pedunculated and polypoid shape, and occur in any part of the nasopharynx, commonly observed on the top, lateral, and posterior walls of the nasopharynx as well as on the posterior edge of the nasal septum. [ 5 ] The mean age of patients with TL-LGNPPA is 32.3 years (range: 9–68 years), and the incidence does not differ according to sex; the tumor size ranges from 0.3 to 4.0 cm. [ 6 ] Because of its location, patients usually present with nasal obstruction and/or nasal discomfort, epistaxis, and headache.…”

“…BRAF mutations were negative in both cases, which is consistent with results reported previously in the literature. [ 5 , 7 ]…”

“…[ 4 ] This tumor is typically located in the nasopharynx arising from the roof or lateral wall of the nasopharynx, and in a few cases, it has been noted to be attached to the posterior nasal septum. [ 5 ] Herein, we present another case of TL-LGNPPA with squamous differentiation located on the posterior nasal septum. Interestingly, the TL-LGNPPA exhibited a different histopathological finding in addition to different morphological and immunohistochemical features compared to previous cases.…”

Efficacy of endoscopic resection and intensity-modulated radiotherapy for thyroid-like low-grade nasopharyngeal papillary adenocarcinoma: a case report

“…Lowgrade nasopharyngeal papillary adenocarcinoma (LGNPPA) is extremely rare among nasopharyngeal neoplasms. To our knowledge, fewer than 70 cases have been publicly reported thus far (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Because of the very low incidence of this disease, there are no guidelines or protocols developed for proper, standardized therapy.…”

“…Endoscopic resection or endoscopic resection-based therapy may be an effective method, especially for small tumors (25,26). Takakura et al reported a case of LGNPPA free of local recurrence and distant metastasis for 5 years after endoscopic resection, thus concluding that patients with LGNPPA have a very good prognosis and that complete resection with an adequate safety margin should the first-line treatment (2). In a recent single-center, retrospective study (1), 23 out of 28 patients included in the study underwent pure endoscopic treatment, with 2 cases of recurrence in the following 7-121 months of follow-up and 0 cases of recurrence or distant metastasis after endoscopic resection was applied a second time for tumor recurrence.…”