Fig. 1

a Cutaneous mass HE × 200 Neoplastic round cells with numerous mitoses (arrows); b) Cutaneous mass Toluidine Blue × 400: numerous metachromatic granules in the cell cytoplasm; c) Renal biopsy: HEx200: Neoplastic round cells replacing the renal parenchyma (one residual tubule still visible); d) Renal biopsy: Toluidine Blue × 400: Regular inconspicuous metachromatic granulations (arrows)