How to differentiate melanoplakia from malignant melanoma in the oral cavity of a patient with a history of smoking?

Differentiating Melanoplakia from Oral Malignant Melanoma

Melanoplakia (melanotic macule) and oral malignant melanoma differ primarily by clinical evolution, location, demographics, and histopathology—with biopsy being mandatory when melanoma cannot be excluded clinically, particularly in males over 60 with palatal or gingival lesions. 1, 2

Key Clinical Distinguishing Features

Demographics and Location

• Melanoplakia typically presents in patients with mean age 47 years, shows 2:1 female predominance, and most commonly affects the lower lip 2
• Oral melanoma presents at mean age 54 years, shows no sex predilection, and predominantly involves the palate and gingiva 2
• The differences in age (p=0.006), gender (p=0.014), and location (p<0.001) are statistically significant and clinically useful 2

Critical Warning Signs for Melanoma

Major signs (presence of ANY one mandates excisional biopsy): 3, 4

• Change in size (progressive growth)
• Change in shape (irregular borders developing)
• Change in color (heterogeneous pigmentation with multiple shades of brown/black)

Minor signs (presence strengthens suspicion when combined with major signs): 3

• Inflammation (reddish tinge within lesion)
• Sensory change (awareness, mild itch)
• Crusting, oozing, or bleeding
• Diameter ≥7 mm

Smoking History Context

• In patients with smoking history, smoker's melanosis must be considered in the differential—this presents as benign macular pigmentation predominantly on anterior mandibular attached gingiva and interdental papillae, typically after the third decade 5, 1
• Smoker's melanosis is macular (flat), while melanoma often becomes nodular or shows progressive elevation 5, 1

Diagnostic Algorithm

Step 1: Clinical Assessment

• Document exact location (lip vs. palate/gingiva vs. buccal mucosa) 2
• Assess for elevation or nodularity—melanoplakia is flat; melanoma often develops nodules or thickening 4, 1
• Evaluate for any major signs (size/shape/color change)—if present, proceed directly to excisional biopsy 3, 4
• Palpate regional lymph nodes (preauricular, cervical, submandibular)—enlargement suggests metastatic melanoma 4

Step 2: Risk Stratification

High-risk features requiring immediate excisional biopsy: 2, 1

• Male patient >60 years old
• Palatal or gingival location
• Any progressive change in size, shape, or color
• Presence of nodularity, ulceration, or bleeding
• Diameter >7 mm with irregular features

Lower-risk features (but still require biopsy for definitive diagnosis): 1, 6

• Female patient <50 years
• Lower lip location
• Stable, flat, uniform pigmentation
• No associated symptoms

Step 3: Definitive Diagnosis

• Complete excisional biopsy with 2 mm margins is the standard—never perform partial biopsy or use laser/electrocautery as tissue destruction compromises histologic assessment 3, 4
• Use surgical scalpel with elliptical incision oriented to facilitate potential re-excision 3, 4
• Histopathology must include: melanocytic nature confirmation, malignancy assessment, Breslow thickness (if melanoma), Clark level, ulceration presence, and margin clearance 3, 4

Critical Pitfalls to Avoid

• Never assume benignity based on location alone—while melanoplakia favors the lip and melanoma favors palate/gingiva, one case of melanotic macule transforming to melanoma has been documented 2
• Do not rely on pigmentation alone—amelanotic melanomas exist and typically show peripheral pigment rim with central nodularity 3
• Avoid observation without biopsy in high-risk patients (male >60, palatal/gingival lesions) even if lesion appears stable 2
• Do not perform frozen sections—these compromise diagnostic accuracy for melanocytic lesions 3

Follow-Up Considerations

• If melanoplakia is confirmed histologically in a male patient >60 with palatal location, closer surveillance is warranted given documented malignant potential 2
• Complete skin and oral cavity examination is mandatory to detect synchronous primary melanomas 4
• In smoking patients with confirmed smoker's melanosis, counsel on cessation as pigmentation may regress 5, 1