Squamous Cell Carcinoma on the Scalp

A 67-year-old man had been aware of a painless, firm, red nodule that had been growing slowly on the right temporal area for 1 year. The lesion occasionally bled.

An excision biopsy was performed; pathologic examination revealed irregular proliferating masses of squamous epithelium invading the dermis. Horn pearls and multiple areas of keratinization also were found.

Drs Edmond K. H. Liu and Alexander K. C. Leung of Calgary, Alberta, report that squamous cell carcinomas most commonly arise from preexisting actinic or solar keratosis. Other premalignant lesions include leukoplakia, radiation keratoses, scars, and chronic ulcers. Squamous cell carcinomas also may develop de novo.

The incidence of squamous cell carcinoma of the skin increases with age and is more common in men. Fair-skinned persons are especially prone to develop these lesions.

Examine patients with squamous cell carcinoma carefully for metastases. Squamous cell carcinomas that arise from solar keratoses have a low likelihood of metastasizing, whereas those that develop from scars, chronic ulcers, and apparently normal skin have a much greater tendency to metastasize. Anaplastic tumors, carcinomas that invade below dermal sweat glands, and exceptionally large tumors also carry an increased risk of metastasis.

This patient's carcinoma arose from solar keratosis. The excision biopsy was curative; follow-up examinations to check for recurrences are indicated.