Malignant conversion of florid oral and labial papillomatosis during topical immunotherapy with imiquimod.

We report a case of a 61-year-old woman suffering from florid oral papillomatosis with a squamous-cell cancer of the floor of the mouth, which was removed by scalpel surgery combined with a radical neck dissection in 1996. Between 1996 and 2000 several histologically benign papillomatous lesions of mouth and lips were removed with laser and electrosurgery. However, the lesions recurred. In July 2000 hyperkeratotic, wart-like lesions were present at the lower and upper lips and at the right angle of the mouth and the adjacent oral mucosa. Overnight treatment with a topical 5% imiquimod cream on a Monday-Wednesday-Friday schedule was initiated. However, due to severe irritation and pain the application had to be reduced to 4 h per night, three times a week, followed by a therapy-free interval of 2 weeks. Despite this treatment consisting of four cycles of 3 weeks (1 week treatment and 2 weeks pause), the lesions increased markedly in size. A biopsy taken from the tumorous lesion from the right angle of the mouth proved to be a squamous-cell carcinoma. The tumors of the labial and oral mucosal sites as well as the right submandibular lymph nodes were removed by wide scalpel excision. The lips were reconstructed by plastic surgery. 24 months after surgical intervention no recurrence nor metastasis to lymph nodes or distal sites were observed.