Patients with a metastatic carcinoid tumor can present with various symptoms, which depend on tumor site and size, the distribution of metastases, and hormonal activity [1]. These patients can present diagnostic and treatment challenges as a result of peculiar, disabling syndromes that are caused by massive hormone production. We describe a patient with the carcinoid syndrome and Quincke edema that improved after treatment with terfenadine (a selective histamine-1 [H₁]-receptor antagonist) and ranitidine (a selective H₂-receptor antagonist).

Our patient was a 50-year-old man with a history of hypertension. Sixteen years earlier, he had had a malignant midgut carcinoid tumor with metastases to local lymph nodes that was diagnosed after a right-sided hemicolectomy. He had also had liver metastases for the last 2 years. For 11 months, the patient received octreotide, 150 µg subcutaneously three times a day, for diarrhea and flushing. A few months ago he presented with episodes of tongue and neck swelling, which, on the basis of provocation test results, could not be related to octreotide or ingestion of food. Laboratory test results showed elevated urinary levels of 5-hydroxyindoleacetic acid and serotonin and a slightly increased methylhistamine excretion. The symptoms diminished during a short course of treatment with oral clemastine, an H₁-receptor blocker. These episodes, which arose primarily during the night at least five times per week, were accompanied by airway obstruction. The patient's medications were changed to a combination of octreotide and recombinant interferon-, 2.5 x 10⁶ IU/d and oral terfenadine (an H₁-receptor blocker), one 60-mg tablet three times a day. During treatment, the episodes of swelling slightly improved. The urinary levels of 5-hydroxyindoleacetic acid were decreased by half but remained elevated. Two months later, after the addition of oral ranitidine (one 150-mg tablet two times a day), his attacks disappeared rapidly. Nine months later, he remains free of symptoms.

In patients with the carcinoid syndrome, biogenic amines such as serotonin, histamine, kallikrein, substance P, prostaglandins, and catecholamines are excessively synthesized, stored, and released. Quincke edema has not been previously reported as part of the carcinoid syndrome. It is usually treated sufficiently by H₁ antihistaminic medication. In our patient, H₁ antihistaminic treatment alone was inadequate, but the attacks disappeared after the addition of ranitidine, a selective H₂ antagonist. Ranitidine has also been effective in treating mastocytosis, a rare disorder characterized by a pathologically increased number of mast cells in various tissues and overproduction of mast-cell mediators such as histamine [2]. This case suggests that, apart from general treatment such as that with octreotide and interferon, selective receptor blockade may be indicated to relieve symptoms in patients with carcinoid [3-5].