Seeing Spots: Eosinophilic Abscess as an Endoscopic Marker of Giardiasis

Abstract

Introduction:Giardia lamblia is recognized as the most common protozoan found in the gastrointestinal tract, with the prevalence up to 60% in developing countries. Though typical symptoms may include diarrhea, abdominal discomfort, nausea, and dyspepsia, these are certainly not ubiquitous. A large retrospective review delineated diarrhea in only 29% of patients and abdominal pain in 71%. Gross upper endoscopic features of Giardiasis are nonspecific, including duodenal ulcers and duodenitis, and may be unremarkable in 75% of cases. Colonoscopic features have rarely been reported. To our knowledge, this case represents the first documentation of eosinophilic microabscesses visualized on colonoscopic examination in association with Giardia lamblia. CASE: A 49-year-old Ethiopian man was evaluated for episodic melena over 6 months. He denied abdominal pain, weight loss, fevers, alcohol or NSAID use. Laboratory testing revealed a hemoglobin of 14.3 g/dL, thrombocytopenia to 83 K/uL and peripheral eosinophilia of 11.1%. On upper endoscopy, a normal esophagus and stomach were visualized, though within the duodenal bulb, edema, inflammation, and an apthous ulcer were identified. Biopsies from the stomach and duodenum noted varied degrees of eosinophilic infiltration in the lamina propria, most prominently in the duodenal bulb, without suggestion of Helicobacter pylori. Colonoscopy revealed multiple subcentimeter white mucosal plaques within the cecum with mild surrounding erythema, as well as 3 small “polyps”. Biopsies from these cecal lesions showed polypoid colonic mucosa with marked patchy eosinophilic infiltration in the lamina propria. Both trichrome staining on duodenal aspirate and stool microscopy revealed moderate Giardia lamblia cysts and trophozoites. The patient was treated with oral metronidazole with resolution of symptoms. DISCUSSION: Screening for Giardia with stool microscopy or stool antigen detection by ELISA can be misguided by false negatives due to irregular parasite shedding. Giardia cysts or trophozoites may be identified in duodenal aspirate or on small bowel biopsy. Visualization of similar mucosal and submucosal white plaques or exudates have been reported in association with other hypereosinophilic disorders such as Eosinophilic Esophagitis. Given our case, visualization of these lesions on colonoscopy may prompt consideration of biopsy and analysis of stool to evaluate for parasitic infections such as Giardia lamblia.1915_A Figure 1. Duodenal Bulb endoscopic findings of edema, erythema, erosions, and superficial ulceration.1915_B Figure 2. Multiple sub-centimeter white mucosal plaques seen in the cecum, and identified throughout the colon.1915_C Figure 3. Cecal biopsy showing polypoid colonic mucosa with marked patchy eosinophilic infiltration in the lamina propria.