Glandular differentiation in epstein-barr virus RNA-expressing nasopharyngeal carcinoma

Abstract

Nasopharyngeal carcinoma (NPC) is described in the 2005 WHO Classification of Head and Neck Tumours as a carcinoma arising in the nasopharynx having light microscopic or ultrastructural evidence of squamous differentiation. In the current definition, adenocarcinoma is excluded. Rare adenocarcinomas of the nasopharynx show papillary growth or are of salivary gland-type, and are not associated with Epstein-Barr virus (EBV).We report the case of a 37-year-old Southeast Asian Chinese male with a non-keratinising carcinoma, undifferentiated subtype arising in the nasopharynx. Within the tumour, there were glandular structures with distinct lumens which were highlighted with mucicarmine. Cytokeratin AE1/3 and epithelial membrane antigen were diffusely positive in the tumour. Like typical non-keratinizing NPC, the tumour demonstrated EBV encoded early RNA (EBER) by in-situ hybridisation. Biopsy from recurrent tumour 2 years later, after radiotherapy and chemotherapy, showed no evidence of glandular differentiation.Glandular differentiation in NPC is exceptional. To our knowledge only 2 previous cases have been reported in white males in the United States where nasopharyngeal carcinoma is rare. We report the first case of NPC with glandular differentiation in Southeast Asia where the tumour is prevalent among ethnic Chinese and Southeast Asians. Nasopharyngeal carcinoma (NPC) is described in the 2005 WHO Classification of Head and Neck Tumours as a carcinoma arising in the nasopharynx having light microscopic or ultrastructural evidence of squamous differentiation. In the current definition, adenocarcinoma is excluded. Rare adenocarcinomas of the nasopharynx show papillary growth or are of salivary gland-type, and are not associated with Epstein-Barr virus (EBV). We report the case of a 37-year-old Southeast Asian Chinese male with a non-keratinising carcinoma, undifferentiated subtype arising in the nasopharynx. Within the tumour, there were glandular structures with distinct lumens which were highlighted with mucicarmine. Cytokeratin AE1/3 and epithelial membrane antigen were diffusely positive in the tumour. Like typical non-keratinizing NPC, the tumour demonstrated EBV encoded early RNA (EBER) by in-situ hybridisation. Biopsy from recurrent tumour 2 years later, after radiotherapy and chemotherapy, showed no evidence of glandular differentiation. Glandular differentiation in NPC is exceptional. To our knowledge only 2 previous cases have been reported in white males in the United States where nasopharyngeal carcinoma is rare. We report the first case of NPC with glandular differentiation in Southeast Asia where the tumour is prevalent among ethnic Chinese and Southeast Asians.