Inverted follicular keratosis.

Inverted follicular keratosis (IFK) is a benign skin lesion that typically presents as an asymptomatic, solitary nodule on the face of middle-aged and older individuals. IFK may mimic malignant lesions, especially squamous cell carcinoma (SCC), both clinically and pathologically. We report a 35-year-old male patient who had an exophytic nodule with papillary surface on his right nasal ala of 3 months' duration. The nodule was solitary, flesh colored, 5 mm in diameter and tended to bleed. The patient received shave excision with cautery under the clinical impression of pyogenic granuloma. Pathologically, diagnostic confusion existed between IFK and SCC. Squamous eddy formation and lack of epithelial dysplasia were suggestive of IFK. The tissue was investigated for the presence of human papillomavirus (HPV) DNA sequences by polymerase chain reaction (PCR) and negative result was obtained. This patient healed satisfactorily after removal of the lesion and no visible recurrence occurred during the following 10 months. The possibility of histologically confusing IFK with SCC, leading to unwarranted disfiguring treatments of a benign lesion, is emphasized.