What are the appropriate evaluation and treatment steps for a patient with a black lesion on the lip, considering potential malignancy and other serious conditions?

Evaluation and Management of Black Lesion on Lip

A black lesion on the lip requires urgent biopsy to exclude malignant melanoma, which carries an extremely poor prognosis with only 12.3% five-year survival for oral mucosal melanomas. 1

Immediate Clinical Assessment

Critical Red Flags for Malignancy

• Change in lesion characteristics: Asymmetry, irregular borders, color variation, diameter >6mm, or ulceration strongly suggest melanoma or other cutaneous malignancy 2
• Patient age >40 years increases suspicion for head and neck squamous cell carcinoma 2
• Tobacco and alcohol use are present in 75% of oral cancers 3
• Duration and progression: Lesions present for years that suddenly change behavior warrant immediate concern 1

Physical Examination Priorities

• Inspect the entire lip surface including vermilion border, mucosal surface, and surrounding skin for ulceration, induration, or satellite lesions 2
• Palpate the lesion to assess depth, fixation to underlying structures, and texture 2
• Examine cervical, submandibular, and submental lymph nodes: Non-tender neck masses are more suspicious for malignancy than tender masses 2, 4
• Assess tongue mobility: Limited movement may indicate muscle or nerve invasion from tumor 2
• Complete oral cavity examination with dentures removed, inspecting floor of mouth, lateral tongue, oropharynx, and tonsils for synchronous lesions 2

Diagnostic Approach

Mandatory Biopsy

Any pigmented lesion detected in the oral cavity must undergo biopsy to exclude malignancy, as oral melanomas present with "chameleonic" appearance and are frequently asymptomatic until advanced. 1

• Excisional biopsy with 3-5mm margins is preferred for small lesions (<1cm) 3
• Incisional biopsy for larger lesions to establish diagnosis before definitive treatment 1
• Do not delay biopsy even if the lesion appears benign clinically, as oral melanomas are notorious for delayed diagnosis contributing to poor outcomes 1

Differential Diagnosis Considerations

The black appearance may represent:

• Malignant melanoma (most critical to exclude) 1
• Pigmented actinic keratosis (17.14% of benign lip lesions, premalignant) 5
• Intradermal nevus (14.28% of benign lip lesions) 5
• Vascular lesions (hemangiomas account for 19.28% of benign lip lesions) 5
• Drug-induced or physiologic hyperpigmentation 6

Treatment Based on Histology

If Malignant Melanoma Confirmed

Wide excision with 2cm safety margins is required, as mucosal melanomas exhibit aggressive behavior with high recurrence rates even after initial 5mm margin excision. 1

• Reconstruction of the lip will be necessary after wide excision 1
• Referral to surgical oncology is mandatory for specialized treatment 1
• Cervical lymph node evaluation with imaging and possible sentinel node biopsy 2

If Premalignant Lesion (Actinic Keratosis, Dysplasia)

• Surgical excision remains the standard approach 5
• CO2 laser ablation is an alternative but may cause more scarring 3
• Photodynamic therapy (ALA-PDT) can be considered for extensive lesions where surgery would cause significant disfigurement, though this is primarily studied for oral leukoplakia 2

If Benign Lesion Confirmed

• Simple excision with primary closure for most benign lesions 5
• Lesions on vermilion only: Use transverse mucosal incision at vermilion-vestibular junction to hide scar 2
• Lesions crossing vermilion-cutaneous border: Vertical incision or wedge excision may be required 2

Critical Pitfalls to Avoid

• Never observe a pigmented lip lesion without biopsy: The "wait and see" approach is dangerous given the aggressive nature of oral melanomas 1
• Do not assume benign appearance: Oral melanomas are frequently asymptomatic and can mimic benign conditions 1
• Inadequate initial margins: If melanoma is confirmed, 5mm margins are insufficient and lead to recurrence requiring re-excision with 2cm margins 1
• Failure to examine the entire oral cavity and neck: Synchronous lesions and nodal metastases must be identified 2
• Patient delay compounds poor prognosis: Educate patients that any changing pigmented lesion requires immediate evaluation 1

Post-Biopsy Management

Wound Care

• Apply white soft paraffin or petroleum-based ointment every 2 hours to prevent drying and cracking 7, 8
• Avoid irritants: Spicy foods, hot beverages, and citrus fruits delay healing 7, 8
• Maintain oral hygiene with soft toothbrush and mild fluoride toothpaste 7
• Warm saline rinses daily to keep the area clean 7

Follow-Up

• Post-operative surveillance ranges 6 months to 2 years for benign lesions 5
• Malignant melanoma requires lifelong surveillance given the 12.3% five-year survival rate and high recurrence risk 1