Answer:
Reasonable guidelines for appropriate margins of excision for cutaneous malignant melanoma are:
1. Malignant melanoma in situ: excisions with 0.5-cm margins
2. Lesions classified as < 1.0 mm in thickness: conservative excisions with margins no greater than 1.0 cm, thereby allowing a primary closure in virtually all instances.
3. Intermediate-thickness lesions (1.0–4.0 mm): 2.0-cm margins are appropriate.
4. Thick lesions (>4.0 mm): margins wider than 2.0 cm may be required to optimize local control.
The Hutchinson freckle (or lentigo malignant melanoma) most often occurs on the face of older individuals, preceded by a gradually enlarging pigmented lesion that is present for many years. It seems to be the least aggressive type of melanoma for which the treatment of choice is surgical excision with margins of 0.5-1.0 cm.
How did the 5-cm rule originate?
The rule was derived from Handley’s recommendations in 1907 which set the course for the management of primary malignant melanoma for the greater part of this century. Handley’s study of malignant melanoma evolved from his interest in cancer of the breast, a disease for which the microscopic studies of Virchow and others had led to the belief that regional lymph nodes served as a filter and temporary barrier, thereby providing a period of protection from systemic dissemination. The concept of early and orderly lymphatic permeation and dissemination was also in the forefront of Handley’s thinking on malignant melanoma when he asserted that the “growth of tendril-like cylinders of cells along the finer lymphatics that surround the primary growth” was the major mechanism of metastasis and that “embolic spread by way of the blood stream is a later event, dependent on the infiltration and invasion of the veins and arteries from concomitant permeated lymphatics.” It is noteworthy that these concepts of dissemination were based on the study of an autopsy of only one patient who had died of widely disseminated metastatic melanoma.
Handley addressed the appropriate extent of excision by advocating a margin of skin around a primary melanoma by “what is judged by present standards to be a safe and practicable distance.” This came to be viewed as 5 cm, although Handley never specified such dimensions. He also advised excising the area of deep fascia, and even a portion of muscle, beneath the origin of the tumor and removing “the lymphatic glands” as part of the first operation.