Differential Diagnosis for Dark Argyric Lines in Skin Lesion with Irregular Borders

Single Most Likely Diagnosis

• Melanoma: This is considered due to the irregular borders and the presence of dark lines, which could indicate a malignant process, particularly if the lines are asymmetric, have varying colors, or are changing over time.

Other Likely Diagnoses

• Seborrheic Keratosis: While typically benign, some variants can have irregular borders and pigmentation that might resemble dark argyric lines, especially if they become inflamed or irritated.
• Dermatofibroma: These can sometimes present with irregular borders and pigmentation, although the dark argyric lines are less characteristic.
• Lentigo or Solar Lentigines: These are benign lesions caused by sun exposure but can have irregular borders and pigmentation, potentially mimicking the described appearance.

Do Not Miss Diagnoses

• Malignant Melanoma with Satellite Lesions: It's crucial not to miss this diagnosis due to its high mortality rate if left untreated. The presence of satellite lesions around a primary melanoma can sometimes appear as dark, irregular lines or spots.
• Kaposi's Sarcoma: Especially in immunocompromised patients, this can present with pigmented, irregular lesions that might resemble dark argyric lines.

Rare Diagnoses

• Argyria: A condition caused by silver exposure, leading to blue-gray pigmentation of the skin and mucous membranes. While it typically presents more uniformly, in rare cases, it could mimic dark argyric lines in a skin lesion.
• Ephelides (Freckles) with Atypical Presentation: Though usually benign and uniform, in rare instances, freckles can present in an atypical manner, potentially mimicking the described lesion, especially if they are very dark or have irregular borders.

Each of these diagnoses requires careful consideration of the patient's history, physical examination, and potentially diagnostic tests like biopsies to determine the correct diagnosis and appropriate treatment.