Cancer involves the scalp either as a primary disease, by metastasis, or by extension from an intracranial carcinoma. Primary scalp cancer is a more dangerous disease than is generally accepted, and the incidence of improper management is frequent. Metastasis to the scalp may be secondary to various types of malignant tumors in different portions of the body, especially if the primary tumor is highly malignant. Carcinomas that are known to metastasize to the scalp1 on occasions are hypernephroma and carcinoma of the stomach, colon, breast, bronchus, thyroid, prostate, and bladder. Montgomery and Kierland2 emphasized that metastases may be limited to the scalp and that a diagnosis of carcinoma of the internal organs may first be established by recognition of the cutaneous metastasis by means of a cutaneous biopsy.
Primary carcinoma of the forehead and scalp starts as a basal or a squamous cell lesion; it is of unknown
Howell JB, Riddell JM. CANCER OF FOREHEAD AND SCALP. JAMA. 1954;154(1):13-20. doi:10.1001/jama.1954.02940350015004