[Histopathologic classification of malignant melanoma of the skin. Retrospective study of 149 cases].
In a retrospective study, the histological slides of 149 cutaneous melanomas are classified according to CLARK et al. (1969) into four levels of dermal invasion and three types of melanoma. Simultaneously, the depth measured in millimeters is added in a slightly modified version of BESLOW's method. This demonstrates the practicability of CLARK'S classification with only a few routine sections. The presumptions are (1) The tumor must be cut through its largest extension. (2) The bordering parts of the lesion in the epidermis must be examinable. (3) The specimen must be excised down to the subcutaneous fat. (4) Beside the Hämalaun-Eosin stains, a Van Gieson Elastica stain should be available to determine the level of invasion. Although it is easy to recognize level V, it is difficult to distinguish level II from III or III from IV in some cases. Our material, as compared to the literature, contained more nodular melanomas and lesions of levels IV and V. The reasons for this are discussed. The prognosis of nodular melanomas is worse than that of superficial spreading melanomas even when they are classified into the same level of invasion. A good correlation between the survival rate and the level of invasion is shown. In addition, the prognostic value of the histological staging can probably be optimized by measuring the vertical extent of the lesions in millimeters.