Chronic appendicitis is a diagnosis unfamiliar to many clinicians, and with no official diagnostic criteria. A symptom duration of > 7 days of chronic or recurrent abdominal pain has previously been suggested to distinguish between acute and chronic appendicitis. The symptoms are often milder than in acute appendicitis, which can lead to misdiagnosis and diagnostic delay.
Acute appendicitis can be caused by luminal obstruction or infection. Genetic factors and environmental influences may also be of importance in the development of appendicitis. The etiology of chronic appendicitis is unknown but is likewise believed to be a result of partial or transient obstruction of the appendiceal lumen. It is unknown whether chronic appendicitis is always preceded by an untreated or insufficiently treated acute appendicitis, or if chronic appendicitis is an independent disease entity. In our first case, gastroenteritis was possibly the initial cause of the chronic appendicitis, however, the travel history contributed to the delay in diagnosis as a tropical disease was suspected. In the second case, suspicion of malignancy led to the 18F-FDG PET/CT scan, which diagnosed appendicitis, as well as mesenteric thrombosis. The recurrent episodes of fever and lower abdominal pain, during the 9 months preceding diagnosis were all self-limiting and therefore not considered characteristic of acute appendicitis.
The radiological findings by CT in chronic appendicitis have been estimated to be identical to the findings in acute appendicitis and include pericecal stranding, dilation of appendix, apical thickening, and adenopathy.
In several cases, pathological findings, rather than the clinical presentation, have led to the final diagnosis. The pathological findings of chronic appendicitis include infiltration by lymphocytes, histiocytes, and plasma cells in lamina propria; hyperplasia of lymphoid tissue; and fibrosis.
In two retrospective studies, including 269 and 322 patients with appendicitis, histological signs of chronic appendicitis were found in 14% and 23% of the cases, respectively.[3,6] In addition, these studies showed that 82–93% of the patients with chronic appendicitis became symptom-free after surgery. Antibiotic treatment is efficient in cases of acute appendicitis, but to our knowledge there are no clinical studies of antibiotic treatment in chronic appendicitis, hence optimal treatment strategy for this condition is unknown.
J Med Case Reports. 2022;16(51) © 2022 BioMed Central, Ltd.