{'fraction_non_alphanumeric': 0.027720739219712527, 'fraction_numerical': 0.01591375770020534, 'mean_word_length': 4.996923076923077, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Primary small cell neuroendocrine carcinoma of oropharynx: A potential diagnostic pitfall with Human papillomavirus (HPV)-related squamous cell carcinoma


 
 
 Small cell neuroendocrine carcinoma (SCNEC) primary to the head and neck region, especially from oropharynx, is very rare. Published data have shown that Human papillomavirus (HPV) positivity may be associated with a better overall survival in these tumors. Here we report a case of p16 positive SCNEC arising from the tonsil.
 
 
 
 A 51-year-old man with former smoking history was evaluated for sore throat and difficulty swallowing. Nasopharyngolaryngoscopy showed a left tonsillar mass and imaging revealed left jugular chain lymphadenopathy with no other evidence of a primary tumor elsewhere, including the lung. Biopsy of the mass was performed which revealed nested proliferation of uniform, hyperchromatic tumor cells with scant cytoplasm, indistinct nucleoli, areas of nuclear molding, and brisk mitotic activity. No keratinization was present, but a vague peripheral palisade was seen in some of the nests. The major differential diagnostic considerations included HPV-related nonkeratinizing squamous cell carcinoma, basaloid squamous cell carcinoma, and SCNEC. Immunohistochemistry revealed tumor cells were positive for AE1/AE3 with partial dot-like perinuclear pattern, cytokeratin 8/18, synaptophysin, and strong p16; negative for P40, P63, cytokeratin 5/6, cytokeratin 7, chromogranin, and CD56. Because SCNEC at any site may be positive for p16, testing for HPV RNA by in-situ hybridization was performed and showed negative for HPV subtypes 6, 11, 16, and 18.
 
 
 
 NA
 
 
 
 This case highlights the differential diagnosis of a “basaloid” appearing carcinoma in the oropharynx. It also reinforces the fact that although p16 is considered a reliable surrogate marker for HPV infection in oropharyngeal squamous cell carcinoma, the same does not hold true for SCNEC.
