Oral squamous-cell carcinoma within a white-sponge nevus.

A 59-year-old woman had thick plaques of leukoplakia on the tongue bilaterally. The condition was initially diagnosed by biopsy as a white-sponge nevus. A second biopsy of a suspicious area on the right side showed squamous-cell carcinoma two years later. It is speculated that prednisone therapy for steroid-dependent intrinsic asthma may have caused a loss of "immunologic surveillance," which permitted development of malignancy in a previously benign condition.