Lichenoid Keratosis

The red patch on this woman's neck is lichenoid keratosis, a variant of seborrheic keratosis. Diagnostic contenders included Bowen disease and superficial basal cell carcinoma.

A 76-year-old woman sought medical attention for an asymptomatic “red spot” on her anterior neck. She had a history of multiple non-melanoma skin cancers.

Key point: Physical examination revealed a 0.85 x 0.6-cm red patch on the anterior neck. The differential diagnosis includes squamous cell carcinoma in situ (Bowen disease), superficial basal cell carcinoma, lichenoid keratosis (an inflammatory variant of seborrheic keratosis), and insect bite. Biopsy showed lichenoid keratosis.

Treatment: Once-daily topical application of 2.5% hydrocortisone cream led to uneventful healing.

Note: This case demonstrates the ambiguity in clinical morphology. When in doubt, you should always do a small skin biopsy!