Decreased skin response to intradermal histamine in cancer patients.

The skin response to intradermal injections of serial dilutions of histamine was studied in 68 cancer patients and 29 noncancer, nonallergic subjects. In cancer patients with primary tumor with or without metastasis, incidence and size of wheals and flare were markedly depressed by comparison with control subjects. Pseudopods were rare, and itching was absent. Similar results were observed in patients in which excisions of the primary tumor dated from less than 5 weeks. In contrast, when excision dated from greater than 2 months, skin tests returned to almost normal values. Intermediate values were obtained in patients with metastases alone. This decrease in skin response to histamine was not due to a peripheral neuropathy in cancer patients, since results of electrophysiologic studies were not different in cancer and noncancer patients. The presence of a tumor mimics the effects of general administration of histamine H1 antagonists on the skin response to histamine.