Editor's Note:

The Case Challenge series includes difficult-to-diagnose conditions, some of which are not frequently encountered by most clinicians, but are nonetheless important to accurately recognize. Test your diagnostic and treatment skills using the following patient scenario and corresponding questions. If you have a case that you would like to suggest for a future Case Challenge, please email us at [email protected] with the subject line "Case Challenge Suggestion." We look forward to hearing from you.

A 51-year-old White man presents to the dermatologist for removal of an epidermal cyst on his left lower eyelid. He has no other complaints. During discussion about the treatment of his cyst, two lesions are seen on the right arm. He was unaware of these lesions; no history could be provided.

The patient's medical history is unremarkable, except for a right inguinal hernia repair. He takes no medications, has no allergies, consumes one alcoholic drink daily, and smokes cigarettes on occasion. He has worked inside his entire life and grew up in South Florida. He reports having several blistering sunburns as a child. There is no family history of skin cancer. Review of the patient's symptoms is unremarkable.

Two solitary, fairly well-circumscribed, 8-mm, pink macules with scale were found on the patient's right arm (Figure 1).

With compression, the lesions blanch slightly but not completely. This prompts a complete skin examination, which is performed and is otherwise unremarkable, with the exception of a 4-mm cyst on the left lower eyelid. Biopsy specimens are obtained from both lesions on his arm using the shave technique, and they are sent for pathologic evaluation.