Mohs micrographic surgery is also often used to treat high-risk tumors with poorly defined clinical borders or with perineural invasion. The method requires special training. The tumor is microscopically delineated, with serial radial resection, until it is completely removed as assessed with real-time frozen sections. Nevertheless, since the technique removes tumor growing in contiguity and may miss noncontiguous in-transit cutaneous micrometastases, some practitioners remove an additional margin of skin in high-risk lesions even after the Mohs surgical procedure confirms uninvolved margins.[Level of evidence: 3iiiDiv]
Radiation therapy is a logical treatment choice, particularly for patients with primary lesions requiring difficult or extensive surgery (e.g., nose, lip, or ears).[4,9] Radiation therapy eliminates the need for skin grafting when surgery would result in an extensive defect. Cosmetic results are generally good, with a small amount of hypopigmentation or telangiectasia in the treatment port. Radiation therapy can also be used for lesions that recur after a primary surgical approach. Radiation therapy is avoided in patients with conditions that predispose them to radiation-induced cancers, such as xeroderma pigmentosum or basal cell nevus syndrome.
Although radiation therapy, with or without excision of the primary tumor, is used for histologically proven clinical lymph node metastases and has been associated with favorable disease-free survival rates, the retrospective nature of these case series makes it difficult to know the impact of nodal radiation on survival.[11,12][Level of evidence 3iiiDii]
Curettage and electrodesiccation
This procedure is also sometimes called electrosurgery. A sharp curette is used to scrape the tumor down to its base, followed by electrodesiccation of the lesion base. Although it is a quick method for destroying the tumor, the adequacy of treatment cannot be assessed immediately since the surgeon cannot visually detect the depth of microscopic tumor invasion. Its use is limited to small (<1 cm), well-defined, and well-differentiated tumors.[Level of evidence: 3iiiDii]
Cryosurgery may be considered for patients with small, clinically well-defined primary tumors. It may be useful for patients with medical conditions that preclude other types of surgery. Contraindications include abnormal cold tolerance, cryoglobulinemia, cryofibrinogenemia, Raynaud disease (in the case of lesions on hands and feet), and platelet deficiency disorders. Additional contraindications to cryosurgery include tumors of the scalp, ala nasi, nasolabial fold, tragus, postauricular sulcus, free eyelid margin, upper lip vermillion border, lower legs, and tumors near nerves. Caution should also be used before treating nodular ulcerative neoplasia more than 3 cm in diameter, carcinomas fixed to the underlying bone or cartilage, tumors situated on the lateral margins of the fingers and at the ulnar fossa of the elbow, or recurrent carcinomas following surgical excision.
Edema is common following treatment, especially around the periorbital region, temple, and forehead. Treated tumors usually exude necrotic material after which an eschar forms and persists for about 4 weeks. Permanent pigment loss at the treatment site is unavoidable, so the treatment is not well suited to dark-skinned patients. Atrophy and hypertrophic scarring have been reported as well as instances of motor and sensory neuropathy.