Primary mucin-secreting adenocarcinoma of the kidney.

A case of mucin-secreting renal cell carcinoma in a 65-year-old man is presented. Both luminal and cytoplasmic mucin was present as demonstrated by Mayer's mucicarmine and alcian blue stains at a pH of 0.9 and 2.5, respectively. In a control series of 18 consecutive renal cell carcinomas, only focal luminal staining with alcian blue at a pH of 2.5 was demonstrated in two cases. Neither cytoplasmic staining for alcian blue nor luminal or cytoplasmic reactivity with mucicarmine was present. The presence of mucin in a tumor does not exclude a possible renal origin.