We diagnosed histologically 178 cases of malignant melanoma in 1990. Thirteen cases were recorded in which the diagnosis of malignant melanoma was not considered by the clinician prior to biopsy or, in retrospect, following pathologic diagnosis. Eight of the 13 lesions were amelanotic. The majority were deeply invasive at the time of biopsy, implying poor prognosis. Despite improvements in early detection of malignant melanoma, a significant subcategory of melanomas escapes clinical diagnosis.
Andersen WK, Silvers DN. 'Melanoma? It Can't Be Melanoma!' A Subset of Melanomas That Defies Clinical Recognition. JAMA. 1991;266(24):3463-3465. doi:10.1001/jama.1991.03470240085038