Inverted Follicular Keratosis

This asymptomatic lesion had been present on a 75-year-old man's right buttock for 2 to 3 years. The 0.5 cm in diameter nodule featured an irregular, flesh-colored surface. Dr Robert P. Blereau of Morgan City, La, performed a shave excision of the lesion and electrocauterized its base. Pathologic examination of a specimen revealed an inverted follicular keratosis. This benign tumor of the follicular infundibulum occurs most often in men; the head and neck-particularly the cheeks and upper lip-are the most common sites. Typically, the flesh-colored nodular or filiform lesions are between 0.3 and 1 cm in diameter.¹ Occasionally, a predominant cutaneous horn may be present. Inverted follicular keratosis is considered by some to be a variant of seborrheic keratosis or verruca vulgaris.