Diagnosis: Malignant melanoma
Our patient’s excisional biopsy, which included 3-mm lateral margins, demonstrated clear architectural and cytological abnormalities consistent with superficial spreading malignant melanoma. Pronounced anisocytosis with prominent nucleoli and unevenly distributed melanin was noted, with atypical melanocytes extending into the papillary dermis. The Breslow thickness was 0.55 mm (Clark level II), and the TNM stage was T1a.
Incidence of malignant melanoma
The incidence of malignant melanoma has more than tripled among Caucasians in the US over the last 40 years; it is the fastest-growing1 and seventh most frequent cancer in the country.2 The risk of developing malignant melanoma is expected to reach 1 in 50 by 2010,3 increasing from 1 in 250 less than a quarter-century ago.1 Elderly men are particularly at risk.
Roughly 20% of melanomas develop in the head and neck regions, and of these approximately 7% to 14% are located on the external ear.4 Melanoma of the external ear most frequently develops on the left side (possibly due to increased sun exposure while driving), usually on the helix.1,4 In a small series by Benmeir et al,4 most patients reported having had an ear nevus whose features (size, color) began changing before diagnosis. Of note, only about one quarter of cutaneous melanomas are discovered directly by physicians.3 Moreover, neoplasms in certain regions of the ear may easily go unnoticed, causing a delay in diagnosis and treatment.1
Lesions are generally found in peripheral areas of the ear and are usually the superficial spreading type; however, nodular melanoma predominated in 1 relatively recent series.7 The lack of subcutaneous tissue on the external ear may contribute to the ease of invasion and poor prognosis identified in several reports.4,7 Hudson et al8 noted more deeply penetrating and thicker lesions at presentation on the external ear in comparison with malignant melanoma of other head and neck areas.
Risk factors
Risk factors for developing malignant melanoma include intense intermittent sunlight exposure (primarily UVB) and blistering sunburns at an early age; skin types and certain ethnicities with limited tanning capability; personal or family history of melanoma; multiple nevi; and immunosup-pression.3 The vast majority of malignant melanomas arise de novo, although very rarely a nevus (usually a giant congenital melanocytic nevus) may undergo malignant transformation.3
Differential diagnosis
The differential diagnosis of malignant melanoma includes atypical nevi, dermatofibromas, lentigos, basal and squamous cell carcinomas, keloids and hypertrophic scars, and seborrheic keratoses.2