A 49-Year-Old with a 4-Week-Old Lesion on Her Toe

Differential Diagnosis

• Amelanotic melanoma
• Cutaneous squamous cell carcinoma
• Nodular basal cell carcinoma
• Subungual fibroma

Diagnosis

The correct diagnosis is amelanotic melanoma, a clinical subtype of cutaneous melanoma with little to no pigment on visual inspection. Amelanotic melanomas account for 2% to 10% of all melanoma cases. Any subtype of melanoma can present as amelanotic; however, nodular melanomas and unclassified melanomas (including desmoplastic and subungual melanomas) are most commonly reported.

Learnings/What to Look for

• Diagnosis is difficult as the appearance is more consistent with a mole, fibroma, hypertrophic scar, basal cell carcinoma, or squamous cell carcinoma
• Risk factors for amelanotic melanoma include exposure to UV rays, moles, fair skin, blond or red hair, older age, family or personal history of melanoma, and high amount of moles
• While no survival difference between pigmented and amelanotic melanomas exists, amelanotic melanomas tend to be associated with a worse overall survival rate than the pigmented counterpart, likely due to delay in diagnosis

Pearls for Urgent Care Management

• Referral to dermatology is warranted for further treatment considerations, including surgical excision

Acknowledgement: Image and case presented by VisualDx (www.VisualDx.com/jucm).

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