Chapter 47: Seborrheic Keratosis

INTRODUCTION

Seborrheic keratosis (SK) are the most common benign cutaneous tumors, and in adults SK are warty, keratotic skin growth that first present after the fourth decade. The measure from a few millimeters to centimeters The color ranges from pink to tan to dark brown. Lesions can be solitary or multiple (Fig. 47.1). Over time, patients develop anywhere from a few to hundreds of SKs. Many patients request removal of SKs, particularly when multiple or large, because of their unsightly appearance.

EPIDEMIOLOGY

Incidence: very common

Age: usually in fourth decade and become more numerous in middle age and beyond

Race: more common in Caucasians

Sex: equal

Precipitating factors: family history with likely autosomal dominant inheritance

PATHOGENESIS

Unknown.

PATHOLOGY

Classically, SKs are well-circumscribed epidermal growths that rise above the surface of the surrounding skin. All feature hyperkeratosis, papillomatosis, and acanthosis. The epidermis contains basaloid cells that show squamous differentiation. Squamous eddies may be present.

PHYSICAL LESIONS

There are many clinical variants of SKs. They range in size from a few millimeters to a few centimeters and most commonly occur on the face, neck, and trunk. They typically first present as well-demarcated tan or light brown macules. With time, they rise to become plaques and develop a warty and stuck-on appearance. Horn cysts become apparent within the lesions. They can occur anywhere on hair-bearing skin and are not seen on the palms and soles.

DIFFERENTIAL DIAGNOSIS

Lentigines, verruca, acrochordons, condyloma acuminatum, acrokeratosis verruciformis, dermatosis papulosa nigra, Bowen’s disease, nevus, epidermal nevus, lentigo maligna, melanoma, and squamous cell carcinoma. The clinical appearance and presence of horn cysts in SKs makes the diagnosis straightforward.

LABORATORY EXAMINATION

None; skin biopsy if suspect malignancy.

COURSE

They present in the fourth decade and persist for years. Over time, they become larger, more pigmented and feature a more verrucous appearance. They typically become more numerous with age. Infrequently, they can regress spontaneously.

KEY CONSULTATIVE QUESTIONS

• Family history of skin cancer

• History of bleeding

• Time of onset

• Was there a rapid onset of numerous SKs?

MANAGEMENT

There is no medical indication to treat SKs, unless they are irritated. Still, the cosmetic appearance bothers many patients. There are multiple modalities for treating SKs including cryotherapy, electrodesiccation, curettage, Q-switched and ablative laser therapy. Most often, the traditional methods of treating SKs are most appropriate. ...