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.
Highlights
Primary nasopharyngeal adenocarcinomas (NPACs) are rare neoplasms, accounting for only 0.38–0.48% of all malignant nasopharyngeal neoplasms [1, 2]
The tumor cells are positive for CK7, SOX10, DOG1, vimentin, S100, and GCDFP-15 and negative for CK20, GATA3, and mammaglobin [47, 48]. This entity is characterized by the gene rearrangement of ETC variant 6 (ETV6), which is a fusion between ETV6 and the Neurotrophic receptor tyrosine kinase type 3 (NTRK3) or RET gene identified with fluorescence in situ hybridization (FISH) [47, 48]
3 cases reported in 3 studies in the literature were negative for human papilloma virus (HPV) [5, 18, 24]. These findings suggest that the origin of TL-low-grade nasopharyngeal papillary adenocarcinoma (LGNPPA) might not be associated with Epstein-Barr Virus (EBV) or HPV infection; further investigations are needed due to the relatively small number of cases
Summary
Primary nasopharyngeal adenocarcinomas (NPACs) are rare neoplasms, accounting for only 0.38–0.48% of all malignant nasopharyngeal neoplasms [1, 2]. We report the case of a 38-year-old Japanese woman with primary TL-LGNPPA and review the relevant literature on TL-LGNPPA. The tumor showed invasive growth into the underlying fibrous connective tissue (Figure 2A) These morphological findings suggested polymorphous lowgrade adenocarcinoma (PLGA) and low-grade nasopharyngeal papillary adenocarcinoma (LGNPPA) as differential diagnoses. Adjuvant therapy was not performed because of the free histopathological margin and information about the clinical characteristics of TL-LGNPPA reported in the relevant literature. We reviewed the relevant literature on TL-LGNPPAs or LGNPPAs with the expression of TTF-1 in terms of the clinicopathological and immunohistochemical characteristics, including our case (Tables 1, 2). In the 28 case reports included in our literature review (Table 1), the mean age of patients with TL-LGNPPA was 32.3 years (range: 9–68 years). In situ hybridization to detect Epstein-Barr Virus (EBV) and human papilloma virus (HPV) was negative in all cases (12/12 cases [100%] and 3/3 cases [100%], respectively)
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