Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

The classification of cutaneous melanoma as to histologic type and depth of invasion hasundergone considerable study in recent years, particularly in the United States and Australia with theevolution of similar classification schemes. The generally defined types of cutaneous melanoma aredescribed as follows:• Lentigo maligna melanoma: A melanoma arising in a Hutchinson's melanotic freckle. Theatypical melanocytes are confined to the basal layer of the epidermis during the radial growthphase. The entity is known as lentigo maligna or Hutchinson's melanotic freckle during theperiod of its intraepidermal growth. It is found primarily in elderly persons.• Superficial (radial) spreading type malignant melanoma: A melanoma characterized by gradualradial enlargement over a period of several months or even years before the onset of itsvertical growth phase.• Acral lentiginous melanoma: A specific biologic form of melanoma occurring commonly on thepalms of the hands and the soles of the feet. It may also occur in areas other than skin, i.e.,in the mucous membranes and subungual areas.• Nodular melanoma: A malignant tumor characterized by early and rapid dermal invasion withno radial growth phase as a developmental stage. These tumors are in vertical growth fromonset.• Malignant melanoma, unclassified: A malignant melanoma for which the radial growth phasehas not been determined.Breslow 1 has emphasized the importance of measuring the thickness (vertical growth) ofpenetration of the melanotic lesion. The measurement represents the thickness of invasion inmillimeters from the granular layer of the epidermis to the greatest depth of penetration of the tumorinto the dermis.The measurement categories for thickness are as follows:< 0.75 mm.0.76 - 1.50 mm.1.51 - 3.00 mm.3.01 - 4.00 mm.> 4.00 mm.Note: < = less than, > = greater than, and the symbol < = less than o_ equal to1Breslow, Alexander--He initiated the measurement of tumor thickness to evaluate the incidenceof recurrent disease in relationship to depth of invasion of the melanoma into the dermis.40