A visibly distressed 50-year-old woman requests an immediate appointment with dermatology for investigation of changes noted recently by her sister-in-law, a hairdresser who commented on the condition of the patient’s neck. The patient denies any symptoms, such as itching or burning, in this area. She further denies having any skin problems elsewhere on her body.

She has a history of a basal cell carcinoma that was removed from her face several years ago. Furthermore, she admits that from a much younger age she has had a great deal of sun exposure, although she feels that her regular use of sunscreen negates any deleterious effects. There is no history of radiation treatment in the affected area.

On examination, this patient has a golden, deep tan over the exposed areas of her skin. Her entire anterior and bilateral neck is quite uniformly hyperemic; by contrast, directly under her chin, the skin is notably white. There is marked accentuation of normal pilosebaceous papularity, and below the scoop neckline, the redness fades rather abruptly. The erythema also fades with digital pressure. No tenderness, increased warmth, or edema is detected on palpation.

While sun-damaged, the rest of the patient’s skin is free of significant lesions.

The patient’s history and examination are consistent with which of the following conditions?