Primary Thyroid-Like Low-Grade Nasopharyngeal Papillary Adenocarcinoma
Primary thyroid-like low-grade nasopharyngeal papillary adenocarcinoma (TL-LGNPPA) is extremely rare and represents less than 0.5% of nasopharyngeal malignancies.1 We herein present a case of a giant TL-LGNPPA in a 50-year-old woman, followed by a brief discussion on this rare disease.
A previously healthy nonsmoking 50-year-old Vietnamese lady with no significant family history of cancer presented with a 4-month history of facial pain. There was no nasal obstruction, bleeding, otitis media, hearing problem, or any other complaint. On clinical examination, no thyroid tumor or cervical lymphadenopathy was found. Nasal endoscopy showed a 4.0-cm mass with a smooth surface located on the roof of the nasopharynx (Figure 1). Magnetic resonance imaging declared a 4 × 4 cm tumor in the nasopharynx. Other diagnostic imaging including chest and abdominal computed tomography scans, as well as a thyroid ultrasound, did not reveal any abnormalities. Finally, a biopsy of the mass on the right was carried out.
Figure 1. Nasal endoscopy revealed a giant nasopharyngeal mass.
Histopathological examination demonstrated tumor cells within the nasopharyngeal subepithelium with an invasive growth pattern. The cells were arranged in papillary structures with fibrovascular cores. The cell nuclei were predominately ovoid with irregular nuclear contours, a thickened nuclear membrane, and a ground-glass appearance. Nuclear grooves were also focally identified. On immunohistochemical examination, the neoplastic cells showed positive expression for TTF-1, cytokeratin CK7, and CK19 and negative reactivity for TG, CK5/6, CK20, smooth muscle actin, p63, and S100. These pathological findings strongly emphasized that the final diagnosis of the patient was TL-LGNPPA.
Primary nasopharyngeal adenocarcinomas (NACs) as a group are extremely rare tumors, which are reported to occupy less than 0.5% of all types of nasopharyngeal malignancies.1 These tumors can be classified into 2 main categories: the conventional or mucosal surface origin type and the salivary gland type, with different morphological features and clinical behaviors.2–4 Nasopharyngeal papillary adenocarcinoma, which belongs to the former category, has been reported in the literature. According to previous studies, TL-LGNPPAs show a pedunculated or polypoid mass, ranging in size from <1 up to 3 cm (median 2 cm). The tumor is most commonly located in the superior and posterior aspects of the nasopharynx and arises from the surface of epithelium.1–5 However, to the best of our knowledge, we describe a giant TL-LGNPPAs with 4 cm in size which is the largest tumor in the literature. Although most tumors that have been previously reported were diagnosed in patients with nasal obstruction, rhinorrhea, bleeding, and otitis media or hearing-related issues,2–7 our patient did not mention any nasal obstruction because the patient’s tumor was located in the roof of the nasopharynx which was an uncommon location.
The majority of nasopharyngeal cancers are closely related to Epstein-Barr virus infection, but the result for the Epstein-Barr virus was negative in our patient and also in preceding reported cases in the literature.8,9Therefore, the relationship between TL-LGNPPA and Epstein-Barr is still uncertain. Because of the limited number of cases, the connection needs to be further studied.
In summary, we report the largest case of TL-LGNPPA in a 50-year-old female patient with papillary features and positive expression of TTF-1 in order to aid both clinicians and pathologists in making appropriate final diagnoses.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
The author(s) received no financial support for the research, authorship, and/or publication of this article.
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