II. History
- Originally described by Frederick Mohs in 1941
III. Indications
- Non-melanoma Skin Cancer
- High risk tumors
- Sites where tissue preservation is critical
- Head and neck tumors (Eyelids, nose, ears, lips)
- Tumors on fingers
- Tumors on genitalia
- Large tumors (Varies by site: 6 mm on face)
- Aggressive tumor on histology (see specific tumors)
- Immunosuppressed patients
- Tumors with poorly defined margins
- Sites where tissue preservation is critical
IV. Contraindications
V. Technique: Performed by a Dermatologist or Surgeon
- Step 1: Prepare site
- Anesthesia: Local Anesthetic
- Curette soft tumor residual from initial biopsy
- Step 2: Excise tumor
- Excise visible tumor with 2 mm margins of normal skin
- Mark orientation with dye (12:00 is cephalad)
- Step 3: In-office histology (requires ~45 minutes)
- Frozen sections examined by Mohs surgeon
- Surgeon maps out positive margins
- Step 4: Excise residual tumor
- Return to step 2 using positive margin map as guide
- Requires 2 stage excision on average
- Step 5: Incision closure
- Small lesions: Healing by secondary intent
- Larger lesions: Reconstruction
- Closure may be delayed for weeks in some cases
VI. Advantages
- Highly effective in Basal Cell Carcinoma
- Rapid histology results best guides excision
- Optimal cosmetic results in sensitive areas
- Similar cost to simple excision with histology
VII. Adverse Effects
- Scarring
-
Hematoma (drain placed at surgery in some cases)
- Anticoagulants need not be stopped before surgery
- Reconstructive tissue graft or flap necrosis
- Higher risk in Tobacco Abuse
- May occur secondary to Hematoma
- Wound Infection (Occurs in 3% of cases)