An enlarging, conical "cutaneous horn" that has been present for more than a year projects 0.5 cm from a 0.7-cm base on the left lateral cheek of the face of a 58-year-old farmer. This lesion is excised, and microscopic 'examination shows basal cell hyperplasia. Some of the basal cells show nuclear atypicalities. This is associated with marked hyper keratosis and parakeratosis. Which of the following lesions best accounts for these findings?
Actinic keratosis occurs on sun-exposed areas and is considered a precursor of squamous cell' carcinoma. When the atypical basal cells occupy the entire thickness of the epidermis, the lesion transforms into a carcinoma in situ. The presence of a hyperkeratotic layer is characteristic. Occasionally, so much keratin is produced that a "cutaneous horn" is formed. A verruca vulgaris may also be a raised lesion, but it is usually more pebbly, and there is no squamous atypia. Superficial epidermal cells show vacuolation or koilocytosis. A keratoacanthoma is a dome-shaped nodule with a central keratin-filled crater, that is surrounded by epithelial cells. Microscopically, it may mimic a squamous cell carcinoma. A dysplastic nevus is typically a flat, pigmented lesion. A seborrheic keratosis can be raised, but it usually appears as a coinlike plaque
Verruca vulgaris
Keratoacanthoma
Dysplastic nevus
Actinic keratosis