A 52-year-old man self-refers to dermatology for evaluation of an irritated lesion on the posterolateral aspect of his neck. It’s been there for years, waxing and waning but always being irritated by his shirt collar or seat belt.
He has shown the lesion to his primary care provider on several occasions. Various topical preparations, including steroid and antifungal creams, have been prescribed—to no avail.
The patient owns a landscaping business. He has worked outdoors since he was in his teens and acknowledges that in his younger years, he was not careful about sun protection. For the past 20 years or so, however, he has worn a wide-brimmed hat and long-sleeved shirt while working.
His health is good in all other respects.
The lesion is a pink, scaly, 2-cm ovoid patch on the left side of the patient’s neck. Several areas of scabbing are seen within the bounds of the lesion, the margins of which are very well defined.
There is much evidence of sun damage on his neck and arms, with prominent pilosebaceous units and rhomboidal lining of the neck skin. Elsewhere, on sun-exposed skin, there are numerous actinic keratoses, telangiectasias, and poikilodermatous changes.
The lesion is biopsied by shave technique and the sample submitted to pathology.
What’s the diagnosis?