How should I evaluate pigmented discoloration of the tongue?

Evaluation of Tongue Pigmentation

When evaluating pigmented discoloration of the tongue, immediately assess for warning signs of malignancy including asymmetry, irregular borders, color heterogeneity, diameter >5-7mm, and recent change in appearance, as oral melanoma carries significant mortality risk if not diagnosed early. 1

Initial Clinical Assessment

Key Historical Features to Obtain

• Age and demographics: Melanoma incidence peaks at 65 years; new pigmented lesions in elderly patients require urgent evaluation 1
• Timing and evolution: Progressive change in lesion size is a major warning sign requiring excision 1
• Medication history: Numerous medications cause benign black hairy tongue, including antibiotics and antipsychotics 2
• Tobacco and substance use: Smoking and excessive coffee/black tea consumption predispose to black hairy tongue 3, 2
• Autoimmune disease history: Screen for thyroid dysfunction when there is personal or family history of autoimmune disease, as 34% of adults with vitiligo have autoimmune thyroid disease 4
• Systemic symptoms: Inquire about fever, night sweats, weight loss suggesting systemic disease 5

Physical Examination Technique

• Use gauze to grasp the tongue to facilitate inspection of lateral aspects, as limited tongue mobility may indicate muscle or nerve invasion from tumor 5
• Examine with bright light and assess the entire oral cavity including floor of mouth, buccal mucosa, and oropharynx 5
• Document lesion characteristics: Note symmetry, border regularity, color uniformity, diameter, and presence of ulceration 1
• Palpate the lesion and base of tongue to detect masses not visible on inspection 5
• Examine regional lymph nodes: Palpate preauricular and cervical nodes, as nontender neck masses are more suspicious for malignancy 5, 1
• Inspect entire skin surface including scalp, face, and neck for other pigmented lesions or signs of melanoma 5

Wood's Light Examination

• Use Wood's lamp to delineate pigment loss in suspected vitiligo, particularly useful in lighter skin types 5, 4
• Wood's light helps differentiate epidermal from dermal pigmentation in fair-skinned patients 6

Differential Diagnosis Framework

Benign Focal Pigmentations

• Black hairy tongue: Elongated filiform papillae with carpet-like appearance on dorsum; typically asymptomatic and associated with smoking, poor oral hygiene, or medications 3, 2
• Amalgam tattoo: Localized gray-blue pigmentation from dental amalgam 7, 8
• Melanotic macule: Benign focal melanin accumulation 7, 8

Systemic/Diffuse Pigmentations

• Physiological/racial pigmentation: Common in darker skin phototypes 6, 7
• Drug-induced hyperpigmentation: Multiple medications can cause diffuse oral pigmentation 7, 8
• Postinflammatory hyperpigmentation: Following mucosal inflammation 7, 8

Concerning Lesions Requiring Biopsy

• Oral mucosal melanoma: Asymmetric, irregular borders, heterogeneous color, diameter >5-7mm, evolving 1, 7
• Melanoma-associated leukoderma: May indicate systemic melanoma 5

When to Biopsy

Perform full excisional biopsy with 2mm margin using surgical knife (not laser or electrocoagulation) for any lesion demonstrating: 1

• Asymmetry, irregular borders, or color heterogeneity 1
• Diameter >5-7mm 1
• Progressive change in size or appearance 1
• New pigmented lesion in elderly patient 1
• Ulceration, bleeding, or inflammation 1
• Diagnostic uncertainty after clinical assessment 6, 1

Histopathologic examination is mandatory to distinguish benign from malignant pigmented lesions, as oral melanoma carries significant mortality risk 1

When to Refer

Refer immediately to dermatology or oral surgery for: 6

• Atypical presentations or concern for malignancy 6
• Diagnostic uncertainty after initial clinical assessment 6
• Lesions requiring procedural interventions (chemical peels, laser therapy) 6
• Incomplete examination due to anatomic constraints (base of tongue not visualized) 5

Laboratory Evaluation

Order thyroid function tests and thyroid autoantibodies when depigmented patches (vitiligo) are present with family history of autoimmune disease, as 34% of adults with vitiligo have autoimmune thyroid disease 6, 4

Management of Benign Black Hairy Tongue

If black hairy tongue is diagnosed clinically: 3, 2

• Identify and discontinue offending medications
• Cease smoking and reduce coffee/black tea consumption
• Gentle brushing of tongue to promote desquamation
• Maintain adequate oral hygiene
• Reassure patient of benign nature

Critical Pitfalls to Avoid

• Never delay biopsy in elderly patients with new pigmented lesions, as melanoma incidence peaks at 65 years and progressive change is a major warning sign 1
• Do not perform partial biopsy of suspected melanoma; full excisional biopsy with 2mm margin is standard practice 1
• Avoid using laser or electrocoagulation for biopsy, as tissue destruction interferes with diagnosis 1
• Do not overlook systemic screening for thyroid disease in patients with depigmented patches, as autoimmune thyroid disease is present in 34% of vitiligo cases 6, 4
• Failing to examine the entire oral cavity and regional lymph nodes can miss synchronous lesions or metastatic disease 5, 1