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ABCDE melanoma evaluation algorithm

The occurrence of melanoma has been on the rise in the United States throughout the last few decades. From 7.5 per 100,000 people affected in 1973, it increased to 22.6 per 100,000 in 2001 among the white populations, a group most prone to this disorder. The mortality rate associated with the occurrence of melanoma is also on the rise, which makes the accurate detection of melanoma at the earliest possible time period extremely vital for improving public health.

In 1985 the ABCD criteria was established as a simple tool for alerting lay persons and primary health care doctors and to help them diagnose the early incidence of potentially curable melanoma. It consists of a series of simple parameters that can be employed in daily life as a simple mnemonic to make people, as well as doctors, aware of the clinical features of melanoma.

The ABCD Criteria

In the mnemonic ABCD; A stands for asymmetry, B stands for border irregularity, C for color variegation and D for diameter greater than 6mm. Asymmetry, border irregularity, and color variegation are all associated with melanoma lesions whose diameter are more than 6 mm. This finding led to the framing of the ABCD criteria. Now these well known parameters are used by clinicians worldwide for determining melanoma malignancy and help to evaluate pigmented cutaneous lesions that may need a specialist’s attention. If required, the character of the pigmented lesions identified through the ABCD criteria are to be ascertained through advanced dermoscopy or biopsy or a combination of both methods for more accurate diagnosis.

Ulcerated lesions are not included in the evaluation as only characteristics of early melanomas are to be explained by means of ABCD. As ulcerated pigmented lesions that look suspicious would have been obviously considered for excision and pathology regardless of other parameters it is unnecessary to include these. Thus, ABCD is an aid to identify a sub group of melanoma, which are early thin tumors and are likely to be mistaken for benign pigmented lesions and left untreated. These criteria were defined to help non-dermatologists in distinguishing normal moles from cancerous melanomas.

Many critics of the ABCD criteria stress that atypical nevi and sebhorreic keratoses have properties similar to those included in the ABCD parameters of melanoma. However, the evidence of reliable sensitivity and specificity with sufficient inter-observer agreement in the application of melanoma established that this is indeed a vital screening tool to be used in clinical assessment. Not all melanomas have all ABCD characteristics but a combination of features makes cutaneous lesions most suspicious for melanoma.

Latest Addition to the ABCD Criteria

Over the later years this ABCD mnemonic as a screening tool for incidences of cutaneous lesions has been controversially debated, verified, and described in order to establish its utility. The parameter D, which stands for diameter of lesions more than 6 mm was reviewed but has not been changed for the time being. Small diameter melanomas are those which are 6 mm or less in diameter. It has been found that small diameter melanomas constituted less than 5% of all invasive melanomas. Thus, it is considered unwise to lower the diameter criteria of the ABCD parameters to increase the sensitivity of melanoma without compromising specificity leading to unnecessary excision. It should be borne in mind that ABCD tool has the greatest capability used in combination while analyzing small lesions.

More importantly, the addition of the parameter E, which recognizes evolving lesions (i.e. lesions that change over time), has been considered and accepted. Thus, the mnemonic now reads ABCDE. The parameter E has been included to emphasize the importance of evolving pigmented lesions in the natural process of melanoma progression. E, denoting “evolving”, explains the dynamic character of this skin malignancy, especially for the diagnosis of nodular melanomas, which greatly contribute to melanoma related deaths. These kinds of melanoma lack asymmetry, border irregularity, color variegation and diameter greater than 6 mm. Lesion change is noticed in 78% of nodular melanomas.

Evolving lesions are defined as those which change in respect to size, shape and symptoms, surface or shades of color. E for Evolving is a more accurate term than the also suggested E for “enlargement” as the latter focuses only on the size and excludes other important feature changes vital for development of melanomas. The role of lesion evolution as a primary characteristic of cutaneous melanoma and resulting in biopsy in diagnosed melanomas is well established. Changes in size, elevation and color taken together is the most probable pointer to melanoma malignancy, other symptoms being bleeding, itching, tenderness and ulceration. Lesions that are enlarged and non-uniform are four times more likely to be melanomas than those which did not meet these criteria.

Organizations like the American Cancer Society and the Skin Cancer Foundation have acknowledged lesion change to be a significant parameter in early diagnosis. Thus, ABCDE is a comprehensive, clear and simple tool to educate the public and physicians alike about the salient features of melanoma. Since early and accurate management of pigmented cutaneous lesions will help physicians to decide whether surgical procedure is necessary to remove such deadly cancers which can be still curable.

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