Leiomyoma with atypical cells (atypical leiomyoma) in the larynx

AIMS: To report and confirm the identity of laryngeal leiomyoma with many atypical cells, which has not been described previously. CASE DETAILS: A 53-year-old man was found to have a polypoid tumour in the larynx. The tumour was excised and the patient has shown no evidence of recurrence over a 5-year period. The tumour tissue comprised intersecting fascicles of spindle-shaped tumour cells with blunt-ended nuclei. Many of the tumour cells showed marked atypia. Mitotic activity in the tumour cells was low, and no atypical mitoses were found. Immunohistochemically, the tumour cells were positive for smooth muscle actin and desmin. p53 overexpression was identified in many tumour cells; the p53 labelling index of the tumour cells was 45%. DNA from tumour cells showed loss of heterozygosity on chromosomes 3p, 5q, 8p, 9p, 10q, 17p and 18q. We diagnosed this case as leiomyoma with atypical cells (atypical leiomyoma) based on the clinical course and pathological and genetic findings. CONCLUSION: This is the first report of atypical leiomyoma in the larynx. The clinical course and pathological findings indicate that although laryngeal atypical leiomyoma contains numerous atypical cells, it is a benign neoplasm.