Adnexal carcinoma of the scalp: aggressive sebaceous differentiation with invasion of the orbital wall and thoracic vertebra.

Abstract Tumors of the scalp are characterized by a heterogeneous clinical spectrum with site-specific features. A wide variety of tumors that arise in the scalp include neoplasms, hamartomas, malformations, and both benign and malignant cysts. Most scalp tumors are benign (98–99%) with only an estimated 1–2% of diagnosed cases reported as being malignant. Of these, adnexal carcinoma is reported in less than 1% of cases. Herein, we report a 65-year-old woman who presented with pain and numbness in her hands with past medical history significant only for a chronic posterior head mass that had never received workup. Computerized topography (CT), magnetic resonance imaging (MRI), and local biopsy demonstrated a large, pedunculated malignant occipital mass that had metastasized to the orbital walls and cervical spine. To our knowledge, this is the largest sebaceous carcinoma to be reported occurring in the scalp. The present case emphasizes the need for older patients with benign scalp lesions to be closely monitored with frequent CT scans for signs of malignant transformation. Furthermore, it is important to diagnose malignant scalp tumors early as they tend to metastasize and cause diffuse symptomatology, which may ultimately result in increased patient mortality.