Granular cell ameloblastoma is a rare,benign neoplasm of the odontogenic epithelium.A case of massive granular cell ameloblastoma in a 44-year-old Thai female is reported.Histopathological features displayed a follicular type of ameloblastoma with an accumulation of granular cells residing within the tumor follicles.After treatment by partial mandibulectomy,the patient showed a good prognosis without recurrence in a 2-year follow-up.To characterize the granular cells in ameloblastoma,we examined the expression of basement membrane(BM) proteins,including collagen type IV,laminins 1 and 5 and fibronectin using immunohistochemistry.Except for the granular cells,the tumor cells demonstrated a similar expression of BM proteins compared to follicular and plexiform ameloblastomas in our previous study,whereas the granular cells showed strong positivity to laminins 1 and 5 and fibronectin.The increased fibronectin expression in granular cells suggests a possibility of age-related transformation of granular cells in ameloblastoma.
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