1
Seborrheic keratosis is the most common epithelial tumor. Clinically, the lesions appear as small 1 to 3 mm barely palpable papules to a large plaque with or without pigment. The surface has a greasy feel and often shows, with a hand lens, fine stippling like the surface of a thimble. Exposed areas are affected. The lesions may be pedunculated, acanthotic, smooth-surfaced, domed and heavily pigmented, but in contrast to melanocytic nevi, do not reflect light and usually have plugged follicular orifices on the surface, giving an almost cerebriform appearance.
Seborrheic keratosis presenting as multiple grayish brown papules and plaques over the face and scalp
Giant seborrheic keratosis over the chest with a stuck on appearance. Note the plugged follicular orifices
2
Keratoacanthoma is a relatively common, rapidly growing epithelial tumor with potential for tissue destruction and rarely metastasis, however, in most cases spontaneous regression. Clinically, it appears as a rapidly growing skin-colored or slightly red, tan/brown firm dome-shaped nodule, often with a central plug. Keratotic plug may appear like a cutaneous horn. Removal of the plug results in a crater. The most common sites affected are exposed areas like cheeks, nose, ears and hands.
Keratoacanthoma presenting as an erythematous nodule with central keratin filled crater over the nose in a 38-year-old male patient
Clear cell acanthoma is benign skin tumor which presents as a moist solitary firm brown-red well circumscribed 5 mm to 2 cm nodule or a plaque on the lower extremities of middle-aged or elderly individuals. The lesion has a crusted, scaly peripheral collarete and vascular puncta on the surface. It is characterized by slow growth and persists for years.
