AIMS: Sinonasal adenosquamous carcinoma (ASC) is a rare tumour classified as a variant of squamous cell carcinoma, exhibiting both squamous and glandular differentiation. ASC has a poorer prognosis compared to sinonasal mucoepidermoid carcinoma (MEC), another uncommon tumour in this region. ASC is believed to originate from metaplastic squamous epithelium, though it may also arise from respiratory epithelium in respiratory epithelial adenomatoid hamartoma (REAH) or seromucinous glands in seromucinous hamartoma (SH). METHODS AND RESULTS: Five cases of sinonasal ASC were retrieved from our registry. Initially, they were classified as sinonasal MEC (n = 3), ASC (n = 2), and carcinoma ex REAH (n = 1). All cases showed adenosquamous malignant proliferation beneath the surface respiratory epithelium with occasional squamous metaplasia, except for one case that showed dysplasia. The respiratory epithelium exhibited an inverted growth pattern consistent with REAH/SH, and displayed atypical sinonasal glands (ASGSH) arising within seromucinous hamartoma. Next-generation sequencing (NGS) revealed multiple pathogenic mutations in two cases, and in case 4 GGA2::PRKCB and EYA2::SERINC3 gene fusions. One case was positive for high-risk HPV. None of the cases exhibited CRTC1/3::MAML2 gene fusion. CONCLUSION: The connection between ASGSH and ASC has not been described in the literature. There is a growing need for additional studies on the morphological, immunohistochemical, and genetic aspects of these tumours. SH/REAH may serve as precursor lesions in the progression of atypical sinonasal glands to malignancy, and their role in tumour development deserves further investigation.
- MeSH
- Carcinoma, Adenosquamous * pathology genetics MeSH
- Adult MeSH
- Hamartoma * pathology genetics MeSH
- Middle Aged MeSH
- Humans MeSH
- Paranasal Sinus Neoplasms pathology genetics MeSH
- Respiratory Mucosa pathology MeSH
- Aged MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
