Verruciform Xanthoma with Equivocal Exfoliative Cytological Diagnosis

Verruciform xanthoma (VX), a papillary or wart-like lesion of the mucosa, is histopathologically characterized by papillary projection of the epithelium and an aggregation of foam cells in the lamina propria. Here, we describe a case of VX in the posterior mandibular gingiva, initially suspected to be a benign lesion based on clinical findings and cytology prior to an excisional biopsy. The patient was a 62-year-old man who had visited a local dentist approximately 1 year earlier, presenting with a white lesion in the left posterior mandibular gingiva that resisted removal by scraping. The lesion was left untreated as there were no subjective symptoms. Thereafter, the surface of the lesion roughened and the patient was referred to our department for a comprehensive examination. A circumscribed, granular mass, 15-mm in diameter, with a red and white surface was observed in the left posterior mandibular buccal gingiva. Exfoliative cytology was performed. The diagnosis was a class III lesion. Excisional biopsy was performed under local anesthesia. Histopathological examination led to a diagnosis of VX. At 1 year postoperatively, the patient is making satisfactory progress without recurrence. Verruciform xanthoma is difficult to diagnose preoperatively, and is commonly resected under a clinical diagnosis of papilloma or benign tumor. A benign lesion was also initially suspected in the present case and cytological analysis performed to confirm absence of malignancy. The lesion could not be diagnosed as VX preoperatively. Verruciform xanthoma can be over-diagnosed based solely on cytological examination because it often involves cellular atypia reflecting its characteristic extension of rete pegs and keratinization of surface cells, indicating the need for care in arriving at a definitive diagnosis.