Dialysis-related amyloidosis on the buttocks.

A 69-year-old man presented with a few years’ history of nodules on the buttocks. Past history included chronic renal failure controlled with haemodialysis for 19 years and a decompression operation for carpal tunnel syndrome. Physical examination revealed a red-brown pediculated nodule 50×20 mm in diameter on the sacral region (Fig. 1A). In addition, 120×80 mm elastic, hard subcutaneous masses were palpable beneath the skin of the buttock. Laboratory findings showed increased levels of blood urea nitrogen (38 mg/dl; normal range 7–19 mg/dl), serum creatinine (6.5 mg/dl; normal range 0.5–0.8 mg/dl) and β2-microglobulin (24.8 mg/dl; normal range 0.9–1.9 mg/dl). Serum electrophoresis yielded normal results. Histological examination of the pediculated nodule and subcutaneous masses revealed massive eosinophilic amorphous deposits throughout the entire dermis and subcutaneous tissues. Eosinophilic materials were amyloid, as revealed by Cotton dyes (Dylon) staining (Direct Fast Scarlet 4BS; Muto Pure Chemicals Co. Ltd, Tokyo, Japan) (1) (Fig. 1B). Immunohistochemical staining showed that amyloid materials comprised β2-microglobulin (rabbit polyclonal anti-Human β2-microglobulin Ab. DAKO cytomation Co. Ltd, Kyoto, Japan) (Fig. 1C). The patient died of pneumonia. Autopsy revealed amyloid nodules in subcutaneous regions of the chest, neck and shoulders. Nodules were also found in the pelvic spaces and greater omentum. However, no amyloid was detected in the heart or gastrointestinal tract. Dialysis-related Amyloidosis on the Buttocks