Pigmented tumor in the nostril.

A 64-year-old man was noted to have a single pigmented lesion in the nostril of his nose. Clinical examination revealed a 5 mm nodular growth and brown lesion. With a presumed clinical diagnosis of malignant skin tumor, a biopsy was performed. The histological examination revealed the unexpected diagnosis of pigmented inverted follicular keratosis. The inverted follicular keratosis is an uncommon benign lesion that is usually diagnosed histologically rather than clinically. It commonly simulates other proliferative skin lesions.