Final answer:
Gastrinomas are a rare disease characterized by tumors that produce excessive gastrin, leading to high stomach acid and complications like ulcers and GERD, despite their typically malignant nature.
Step-by-step explanation:
Gastrinomas are a rare disease despite the malignant nature of most tumors. Gastrinomas are neuroendocrine tumors that typically arise in the pancreas or the duodenum and are characterized by the excessive secretion of the hormone gastrin, which in turn causes the stomach to produce too much acid. The malignant nature of these tumors can lead to complications, but they are considered rare, and symptoms can be managed with proper medical treatment. Additionally, because of the excessive acid production, patients with gastrinomas may suffer from recurrent ulcers and gastroesophageal reflux disease (GERD).