Farmer and Hood

 
"The clinical appearance of melanoma usually is that of a pigmented papule or nodule that generally is asymmetric. It is not necessarily round or oval in shape, and many times, the shape cannot fit into a definitive pattern. It has an indistinct border and a variable color, ranging from shades of brown to red to blue to black or white. At the time of diagnosis, the lesions usually are greater than 6 mm in diameter, although it is clear that a melanoma begins as a small lesion and then expands. The 6-mm measurement is used as one clinical guide to help determine when a biopsy should be performed on a new or suggestive lesion. Also, melanomas tend to have a different appearance from that of the other pigmented lesions in the patient. This has been described as the "ugly duckling" sign. Melanomas tend to have areas of regression, and this is made clinically evident by the appearance of a notch in a lesion, areas of hypopigmentation or depigmentation within the melanoma, or an asymmetric halo around the skin lesion."
 
Farmer ER, Hood AF. Pathology of the Skin. 2nd Edition. New York: McGraw-Hill Companies, Inc., 2000: 1136–7.
 

Brief critique

 
What Farmer and Hood advise for clinical diagnosis of melanoma is the ABCDs with the added distraction of the opening dizzying statement that "The clinical appearance of melanoma usually is that of the pigmented papular nodule . . ." In fact, melanoma, at the outset, is a tiny macule. At that flat stage melanoma is curable and that is precisely what must be driven home forcefully to both patients and physicians if prevention of death from melanoma is to be achieved consistently.
 
Phrases like "ugly duckling" for melanoma are as unhelpful as "funny-looking mole," a favorite expression of Clark and his acolytes for characterizing dysplastic nevus clinically. Clichés such as those do not enable a critical thinker to come to diagnosis with specificity and they surely are impediments to teaching repeatable, reliable criteria for diagnosis to physicians and patients. Criteria must be set forth logically and lucidly in a manner that any rational person can comprehend immediately and employ readily.
 
By the time that regression is seen in a melanoma, the lesion is many years old. Although such a lesion may be curable by simple excision because metastasis of neoplastic cells has not yet occurred, that is not true of all such lesions. In fact, the single worst sign for prognosis of primary cutaneous melanoma is complete regression of it; that finding is associated, nearly invariably, with death from metastasis. If complete regression of melanoma signifies a fatal outcome, partial regression of melanoma cannot herald glad tidings.