What is the differential diagnosis (D/D) for a hypopigmented raised lesion over the cheeks just below the lower eyelids?

Differential Diagnosis for Hypopigmented Raised Lesion on Cheeks Below Lower Eyelids

The most critical first step is to exclude melanoma (particularly amelanotic melanoma) and other malignancies through complete excision with a 2 mm margin of normal skin if there is any suspicion of malignancy, rather than performing a partial biopsy. 1, 2, 3

Primary Differential Considerations

Benign Lesions

• Seborrheic keratosis - Can present as raised lesions and must be distinguished from pigmented basal cell carcinoma, as these lesions can mimic melanoma and other malignancies 4
• Pityriasis alba - Typically presents as ill-defined, scaly patches of hypomelanosis on the cheeks of children with atopic diathesis, though these are usually flat rather than raised 5
• Nevus depigmentosus - A stable, congenital leukoderma that shows reduced melanin content but typically presents as flat hypopigmented patches rather than raised lesions 5, 6

Malignant/Premalignant Lesions to Exclude

• Amelanotic or hypopigmented melanoma - Can present with reduced pigmentation and must be excluded through complete excision rather than biopsy 1, 2
• Hypopigmented mycosis fungoides - Presents as hypopigmented macules or patches, more common in darker skin types (Fitzpatrick IV-V), often with pruritus, and requires histologic confirmation 7, 8
• Basal cell carcinoma - Can be pigmented or hypopigmented and must be differentiated from seborrheic keratosis 4

Clinical Assessment Algorithm

Warning Signs Requiring Immediate Excision

• Change in size, shape, or color - Any pigmented lesion with one or more of these major signs requires referral or excision 4, 3
• Diameter ≥ 7 mm - Increases suspicion for melanoma 3
• Inflammation, sensory change, crusting, or bleeding - These are major warning signs for malignancy 3
• Progressive growth - A progressive change in lesion size is a major sign requiring excision 2

Physical Examination Specifics

• Examine the entire skin surface including scalp - To detect second primary melanoma or metastases 1, 2
• Palpate all regional lymph nodes (preauricular and cervical for facial lesions) - Regional lymph node enlargement is highly suggestive of melanoma with nodal metastasis 1, 2
• Assess for scale - Presence of scale may suggest pityriasis alba or tinea versicolor (though tinea versicolor favors upper trunk) 5
• Evaluate for pruritus - Common in hypopigmented mycosis fungoides 7

Diagnostic Approach Based on Clinical Suspicion

If Any Suspicion of Malignancy

• Perform complete excision with 2 mm margin using a scalpel (not laser or electrocautery) to preserve tissue for histopathological examination 1, 2, 3
• Send all excised tissue for histopathology - Frozen sections should be discouraged 1
• Document excision margins in the operation note 1

If Clearly Benign Appearance

• Seborrheic keratosis can be treated with surgical excision, electrocautery, or laser therapy once confirmed as benign 4
• Pityriasis alba typically resolves spontaneously and is associated with atopic diathesis 5

Critical Pitfalls to Avoid

• Never perform partial biopsy of a potentially melanocytic lesion - There is risk of misdiagnosis if only partially examined, and entire lesion examination is necessary to assess maximum thickness 1, 2
• Do not use laser or electrocoagulation for initial excision of suspicious lesions - Tissue destruction compromises diagnosis and assessment of histological prognostic factors 1, 4, 2
• Do not rely on photographic evaluation alone - Cases of melanoma mimicking seborrheic keratosis have been documented 3
• Do not assume hypopigmentation excludes melanoma - Amelanotic melanoma exists and hypopigmented mycosis fungoides can mimic benign conditions 7, 8
• Consider patient's skin type - Hypopigmented mycosis fungoides is more common in darker skin types (Fitzpatrick IV-V) 7