PATHOLOGY OF TUMOR-STROMA INTERACTION IN MELANOMA METASTATIC TO THE SKIN

Tumor invasion and metastasis formation largely depend on tumor-stroma interaction. In the present study morphological correlates of tumor-s troma interaction were examined in 344 melanoma lesions metastatic to the skin. In particular, the presence of simple infiltration into the surrounding dermis or subcutis without evident stromal reaction, the i ncorporation of pre-existent dermal collagen or subcutaneous fat cells into the tumor bulk, and the formation of a peritumoral capsule or in tratumoral fibrous septa were evaluated. Our results showed that simpl e infiltration into the surrounding tissue as well as the incorporatio n of preexistent stroma tissue without destruction is associated with poor outcome, whereas capsule and fibrous septa are favorable prognost ic signs, particularly in subcutaneous lesions. Remarkably, simple inf iltration is a prognostic indicator independent of the location of the metastasis (locoregional or distant), as shown by multivariate analys is. These data indicate that morphological aspects of tumor-stroma int eraction in metastatic skin lesions of melanoma may reflect biological behavior of the tumor cells, may facilitate a pathological subclassif ication of metastatic melanoma in addition to clinical data, and are d irectly related to the patient's outcome. Copyright (C) 1995 by W.B. S aunders Company.