PARENCHYMAL-STROMAL INTERACTIONS IN NEOPLASIA - THEORETICAL CONSIDERATIONS AND OBSERVATIONS IN MELANOCYTIC NEOPLASIA

The paper briefly reviews the reciprocal and continuous reciprocal int eractions between epithelia, mesenchyme, and extracellular matrix in t he development and maintenance of organismal form in multicellular org anisms in the animal kingdom and describes the progressive changes in parenchymal-stromal interactions in melanocytic neoplastic development and progression, In addition to the parenchymal stromal form in non-l esional skin seven different and unique stromal patterns are described . These have been termed: 1) The stroma (diff-regress) of programmed d ifferentiation leading to lesional regression characteristic of common nevi; 2) Concentric eosinophilic fibroplasia (cef), the hallmark of p recursor nevi (dyplastic nevi) with and without melanocytic nuclear at ypia; 3) Fibroplasia with angiogenesis (fa) commonly seen in superfici al spreading melanoma without metastic competence (SSM); 4) Lamellar f ibroplasia (If) seen in precursor nevi and melanomas with and without metastatic competence; 5) Diffuse fibroplasia with angiogenesis (dfa), 6) Narrow, uniform concentric eosinophilic fibroplasia (nucef), 7) No parenchymal-stromal interaction (nopsi); the last three being seen in the heterogeneous stroma of melanomas of the superficial spreading ty pe with metastatic competence, The changes in neoplastic stroma procee d in concert with the changes in the parenchyma characteristic of mela nocytic tumor progression.