ABSTRACT
Cyclic vomiting syndrome is a disorder characterized by recurrent, discrete, stereotypical episodes of nausea and vomiting. Although chronic or recurrent appendicitis may be a cause of recurrent abdominal pain, it rarely meets the diagnostic criteria for cyclic vomiting syndrome. Furthermore, mast cell counts are histologically high in chronic appendicitis. We report a 10-year-old Japanese girl with a cyclic pattern of vomiting that met the stringent diagnostic criteria for cyclic vomiting syndrome, and which was resolved after appendectomy. Histopathologic examination of the resected appendix showed not only acute mucosal inflammation but also chronic inflammatory changes. Because we speculated that recurrent or chronic appendicitis may have been related to the patient's vomiting bouts, we also immunohistochemically investigated the density of mast cells in the specimen. We found that the mast cell density was markedly high in the lamina propria of the appendix. In our patient, a type I hypersensitivity reaction with release of mediators by mast cells could have been the initial factor triggering the recurrent appendicitis, and this stressor could have initiated the vomiting cascade. In conclusion, chronic or recurrent appendicitis could be one of the causes of cyclic vomiting, and must be considered in the differential diagnosis of cyclic vomiting syndrome.