I have thickening under my scalp could it be cancer are what?

Scalp Cyst: Trichilemmal or pilar cysts are common intradermal or subcutaneous cysts, occurring in 5-10% of the population. Greater than 90% occur on the scalp, where trichilemmal cysts are the most common cutaneous cyst. Trichilemmal cysts are almost always benign. They may be sporadic or they may be autosomal dominantly inherited. Surgical excision is the only treatment.