Cutaneous metastasis of renal cell carcinoma with Zellballen-like inflammatory reaction pattern on immunohistochemical studies.

Skin tumors show variable infiltration by subtypes of inflammatory cells. The composition of these cellular infiltrates, particularly tumor-associated macrophages and dendritic cell numbers, may be responsible for skin tumor progression or regression. In addition, these cells may give rise to diagnostic dilemmas on immunohistochemical studies. The authors report on the local inflammatory reaction to a metastatic renal cell carcinoma to the skin. Histologic examination and immunohistochemical studies demonstrated zellballen-like changes with S-100-positive spindled cells identified around and within tumor cell nests. The role of tumorassociated macrophages and dendritic cells in the skin is discussed.