Increased serum levels of squamous cell carcinoma-related antigen in pemphigus

Serum levels of squamous cell carcinoma-related antigen (SCC-RAG) were measured in five cases of pemphigus, five cases of bullous pemphigoid and 18 cases of benign and malignant dermatoses other than SCC. The SCC-RAG titres were significantly raised in four of five patients with pemphigus, while they remained within the normal range in the other dermatoses except in one case. In three pemphigus cases in whom serial measurements were made, SCC-RAG levels seemed to be related to disease activity. The SCC-RAG levels in blister fluids were much higher than those in serum, suggesting that the skin is a major source of serum SCC-RAG. These results show that SCC-RAG is increased not only in SCC, but also in some cases of pemphigus, and suggest that pemphigus antibodies may cause the production or release of SCC-RAG.