Surgical excision of lesions may provide definitive treatment or tissues may need to be surgically excised for the purpose of diagnosis to guide further treatment or care (a biopsy). Lesions in the skin or deeper tissues may be benign (non-cancerous) or malignant (cancerous). Even benign lesions, that do not spread or invade surrounding tissues, may require excision if they are causing a functional or cosmetic problem. Lipomas and cysts are examples of benign lumps that are commonly excised for this reason. Examples of surgical biopsies that may be requested by physicians to reach a diagnosis and guide further medical care include lymph node biopsies; temporal artery biopsies, for the diagnosis of giant cell arteritis; or muscle biopsies to aid in the diagnosis of conditions causing muscle weakness or pain.