Mohs Micrographic Surgery: Indications and Technique
Mohs micrographic surgery (MMS) is a specialized surgical technique for the excision of skin cancers, particularly non-melanoma types, with the goal of complete tumor removal while preserving surrounding healthy tissue. This technique combines surgical excision with immediate microscopic examination, allowing for real-time assessment of margins and minimizing the risk of recurrence.
Topics: Mohs, skin cancer, surgery
Overview / Definition Mohs micrographic surgery (MMS) is a precise surgical technique designed for the removal of skin cancers, particularly basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The procedure involves the stepwise excision of cancerous tissue, with immediate histological examination to ensure complete removal while preserving as much healthy tissue as possible. This technique is named after Dr. Frederick Mohs, who developed it in the 1930s. Epidemiology Skin cancer is the most common malignancy in the United States, with over 5 million cases treated annually. The incidence of non-melanoma skin cancers, particularly BCC and SCC, has been rising. Key epidemiological factors include: Age: Most cases occur in individuals over 50 years old. Skin Type: Fair-skinned individuals are at higher risk. Sun Exposure: Chronic UV exposure significantly increases risk. History of Skin Cancer: Previous skin cancers predispose individuals to future tumors. Pathophysiology / Mechanism Non-melanoma skin cancers arise from keratinocytes due to a combination of genetic mutations and environmental factors, primarily ultraviolet (UV) radiation. The pathogenesis involves: DNA damage from UV radiation causing mutations in oncogenes and tumor suppressor genes. Altered cellular signaling pathways leading to uncontrolled proliferation. Immune evasion mechanisms allowing tumor cells to survive and proliferate. Clinical Presentation Skin cancers treated by Mohs surgery typically present as: Basal Cell Carcinoma: Pearly nodules, often with telangiectasia, ulceration, or crusting. Squamous Cell Carcinoma: Scaly plaques or nodules that may be red and crusted. Other Tumors: Rarely, MMS may be indicated for certain melanoma in situ or other tumors. Additional signs may include local tenderness, itching, or bleeding. Diagnosis / Workup The diagnosis of skin cancer is primarily clinical, supplemented by: Biopsy: Excisional, punch, or shave biopsy to confirm diagnosis. Imaging: R