Secondary Nasopharyngeal Mixed Adenoneuroendocrine Carcinoma After Radical Radiotherapy for Nasopharyngeal Carcinoma: A Rare Case and Literature Review

Donglan Huang,^1,* Chunyue Huang,^1,* Hongmei Wang,^1,* Lizhen He,^1,2,* Jian Zhang,^1,* Xi Zhong,^1,3 Ziqian Guo,^1,4 Yawei Yuan,¹ Weijun Zhang<sup>1

1</sup>Department of Radiation Oncology, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou, People’s Republic of China; ²Department of Pathology, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou, People’s Republic of China; ³Department of Radiology, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou, People’s Republic of China; ⁴Endoscopy Center, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Weijun Zhang; Yawei Yuan
Department of Radiation Oncology, Affiliated Cancer Hospital & Institute of Guangzhou Medical University, 78 Hengzhigang Road, Guangzhou, 510095, People’s Republic of China
Tel + 86 20 66673662; +86 20 62931358
Email [email protected]; [email protected]

Abstract: The incidence of primary mixed adenoneuroendocrine carcinoma (MANEC) is rapidly increasing. MANEC mainly arises from the gastrointestinal tract, but occasionally it occurs as a pathological type of second primary malignancy (SPM). These SPMs can occur in the nasopharynx. Herein we describe the case of a first secondary nasopharyngeal MANEC that was detected 20 years after radical radiotherapy for nasopharyngeal carcinoma. The patient was a 50-year-old man who was admitted to our hospital after experiencing 1 month of left nasal congestion and ipsilateral tinnitus caused by a nasopharyngeal mass that was detected via physical examination and magnetic resonance imaging. A biopsy specimen from this nasopharyngeal lesion led to a histopathological diagnosis of recurrent nasopharyngeal carcinoma. He underwent high-dose palliative radiotherapy, followed by a course of gemcitabine–cisplatin-based adjuvant chemotherapy. These treatments failed to achieve local control of the tumor, and progressive left earache emerged. Another two forceps biopsies of the external auditory canal mass were conducted, and immunohistochemical testing for adenocarcinoma and neuroendocrine carcinoma markers including CK7, CK8, CK18, carcinoembryonic antigen, synaptophysin, chromogranin A, and CD56 was conducted. The diagnosis of MANEC was ultimately confirmed 5 months after the first visit, and one additional cycle of chemotherapy was subsequently performed. The patient died of hepatic metastases 8 months after the final diagnosis. Knowledge of this rare case will raise awareness of MANEC as a new pathological type of SPM originating in the nasopharynx, which will reduce delays and promote early diagnosis.

Keywords: adenocarcinoma, head and neck, neuroendocrine carcinoma, second primary malignancy