Making an accurate diagnosis
The ABCD approach
The ABCD approach to recognizing potentially malignant melanotic lesions is evaluation for Asymmetry, Border irregularity, Color variegation, and Diameter >6 mm (roughly pencil eraser size). Patients who report recent changes in the characteristics of existing nevi should be examined carefully.
Biopsy, histology, dermatoscopy
Excisional biopsy and histologic examination are required for diagnosis, which is facilitated by histochemistry and immunohistochemistry techniques. Architectural criteria are of greater diagnostic significance than cytologic features, rendering fine- needle aspiration or curettage less helpful and unnecessary for diagnosis.3 Before excision, corresponding areas of lymphatic drainage should be examined, and subsequently a full-thickness biopsy with 2- to 5-mm lateral margins should be performed.9
Dermatoscopy is an excellent noninvasive method for in vivo examination of suspected melanomas, being a potentially powerful resource for general practitioners and dermatologists alike. In this procedure, the suspected melanoma is covered with mineral oil, alcohol, or water and viewed with a hand-held dermatoscope, which magnifies from 10 to 100 times, allowing visualization of structures at and below the skin surface. In comparison with clinical analysis, the sensitivity of dermatoscopic diagnosis is increased by 10% to 30%.3
Management: Surgical excision and special considerations
Difficulties in managing ear melanomas arise due to the ear’s importance in daily functioning and to patient’s cosmetic concerns. Initial reports of malignant melanoma of the external ear indicated a poorer prognosis compared with lesions in other areas,5,6 but subsequent studies did not corroborate these findings.
Surgical excision
Surgical excision is the standard of care for malignant melanoma. The World Health Organization recommends excision margins of 5 mm for in situ lesions, and 20 mm for melanomas >2.1 mm thick,10 although treatment of external ear lesions must be individualized given the thin skin and various anatomic subdivisions of the ear. Pockaj et al1 found margins of at least 10 mm to be associated with the lowest recurrence risk.
Several techniques have been employed in lesion excision and postexcisional defect repair, including wedge resection, partial and total auriculectomy, wide excision and skin grafting, and Mohs micrographic surgery.4 Wedge resection was associated in 1 study8 with significantly increased melanoma recurrence when compared with wide local excision using 10-mm margins or total auriculectomy.
Skin and subcutaneous tissue should always be excised, but perichondrium is generally spared unless involved with the tumor.1 However, Narayan et al11 suggested cartilaginous excision in melanomas >1 mm thick, regardless of the presence of tumor infiltration. Various types of flaps are used in reconstructing surgical defects.11