Abstract and Introduction
Abstract
Background: The colon shows frequent eosinophilic infiltration in allergic proctocolitis of infants, whereas in adults, eosinophilic infiltration of the colon is less defined and may be found in different conditions including drug-induced colitis, even though the pathological findings are often inconsistent.
Aim: To quantify eosinophils in the mucosa of normal controls and to compare them with those of patients with abdominal symptoms related to 'drug colitis'.
Methods: Mucosal biopsies were obtained during colonoscopy in 15 controls and in 27 patients with abdominal symptoms, a history of probable 'drug-related colitis' and without obvious causes of eosinophilia.
Results: The drugs related to the patient symptoms were nonsteroidal anti-inflammatory drugs (70%), antiplatelet agents (19%) and oestroprogestinic agents (11%). Colonoscopy was normal in 30% of patients and abnormal in 70%. Histology showed low content of inflammatory cells and normal crypt architecture in-patients with endoscopy similar to inflammatory bowel diseases. The eosinophil score was significantly higher in the left side of the colon in the patient group compared with controls.
Conclusions: The finding of an increased eosinophil count limited to the left (descending and sigmoid) colon is an important clue towards a diagnosis of drug-related colitis
Introduction
The diagnosis of primary eosinophil-associated gastrointestinal disorders (EGID) is based on morphological evaluation of biopsy samples of the mucosa and/or deeper parts of a viscus in the different segments of the gastrointestinal tract. As for the colon, this is frequently involved by eosinophilic infiltration in allergic proctocolitis of infants, which represents a well-defined condition.
In adults, eosinophilic infiltration of the colon is less well-defined and may be found in several different conditions such as eosinophilic colitis, hypereosinophilic syndrome, systemic connective tissue diseases, infections, parasitoses, vasculitis and inflammatory bowel diseases (IBD).
Moreover, several recent studies and reviews have focused on the function of eosinophils in the pathophysiology of gastrointestinal hypersensitivity reactions and it has been stated that there is substantial evidence that allergic reactions similar to allergic proctocolitis in infants also exist in adults. Such patients, however, represent a diagnostic challenge as they display variable and nonspecific clinical features, and a final diagnosis is usually made after careful clinical examination and exclusion of several different pathological conditions.
Among these patients are included those with drug-induced eosinophilic colitis, mostly described as single case reports and with important clinical manifestations. However, the lack of accurate details in these case reports is remarkable and even in specific reviews, the role of these cells is completely skipped or considered with generic statements such as 'eosinophils are sometimes conspicuous'.
A substantial limiting factor is the consideration that there is lack of data on the quantity and location of eosinophils in the colon of healthy individuals, with studies in healthy controls stating that these cells are infrequently seen, with a maximum of one-three eosinophil/high power field (HPF). In paediatric subjects without apparent pathological diseases, the highest concentration of eosinophils (but no more than 50 cells/HPF) is found in the right colon, with lower concentrations in the left colon. Similar findings have been recently reported also in adults, where intramucosal eosinophils are commonly present in the proximal colon, but they show only mild fluctuations with ambient allergen exposure.
The aims of the present investigation were: (a) to quantify the presence of eosinophils in the mucosa of patients without gastrointestinal pathology (normal controls); (b) to compare the results achieved with those obtained in-patients with abdominal symptoms related to 'drug colitis' and to establish relationships, if any, with putative factors.