Pathogenic Somatic Mutation of DICER1 and Clinicopathological Features in Nasal Chondromesenchymal Hamartomas: A Series of Nine Cases.

Nasal chondromesenchymal hamartoma (NCMH) is a rare benign polypoid mesenchymal tumor arising in the nasal cavity and/or paranasal sinuses. Recognizing these sporadic, rare lesions is crucial, as surgical complete removal of the mass is the common treatment approach. This retrospective study analyzed the demographics, symptoms, and imaging data of 9 patients diagnosed with NCMH between January 2017 and June 2023, possibly representing the largest single-center adult case cohort to date. Diagnostic techniques included nasal endoscopy, CT/MRI scan, immunohistological studies, and morphologic comparisons. Pathologic specimens were subjected to Sanger sequencing of exons 24 and 25 of DICER1. The average age of 9 cases was 24.4 years, and the oldest was 55 years. Four of the patients were children, ranging from 1 year old to 11 years old, with an average of 4.5 years. Nasal congestion is the most common registered symptom. Endoscopic findings showed that most patients had smooth pink neoplasms or polypoid masses in the nasal meatus. Radiologic scanning revealed soft-tissue density masses that occupied the nasal cavity. Histologically, the characteristic structure of NCMHs is immature cellular cartilage nodules and mature cartilage nodules distributed in a loose mucoid matrix. Five of the 9 patients had somatic DICER1 missense mutations. Four of the patients with DICER1-mutated NCMH exhibited a p.E1813 missense hotspot mutation. We also report a case of a rare p.P1836H missense mutation. The detected DICER1 somatic mutations provide compelling evidence of an association with the DICER1 tumor family. We emphasize the importance of pathologic consultation and the need for pathologists to accumulate experience in NCMH diagnosis to avoid misdiagnosis.