Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital and National Yang-Ming University School of Medicine, Taiwan
Keywords: continuous ambulatory peritoneal dialysis; peritoneal eosinophilia
Case
A 71-year-old Chinese man presented in November 1995 with end-stage renal disease. He started on haemodialysis at an outpatient dialysis facility and then changed to CAPD 1 year later due to repeated occlusion of arteriovenous fistulae. Treatment was uneventful until three episodes of bacterial peritonitis developed from September to December 1998. At each episode, peritoneal effluent showed an increased leukocyte count with neutrophil predominance. The patient responded well each time to 2 weeks of antibiotics by intraperitoneal (i.p.) administration according to the susceptibility test of peritoneal effluent cultures. Unfortunately, abdominal pain and cloudy ascites occurred on 27 February 1999. Peritoneal effluent analysis showed leukocytes of 340/µl with 50% neutrophils, 17% lymphocytes, and 14% eosinophils. Empirical antibiotics with cefazolin plus tobramycin were administered i.p. However, cloudy ascites persisted and follow-up analysis of peritoneal effluent showed leukocytes of 140/µl with 29% neutrophils, 1% lymphocytes, and 65% eosinophils. Effluent cultures for bacteria and fungi were negative and antibiotics were used for 4 weeks until leukocytes of peritoneal effluent decreased to 43/µl. Three days after discontinuation of antibiotics, severe abdominal pain with cloudy ascites recurred. Peritoneal effluent disclosed white cells of 230/µl with 2% neutrophils, 7% lymphocytes, and 80% eosinophils (Figure 1), with Grams' stain negativity. The same IP antibiotics were used and the patient was referred to our institution in April 1999.
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Comments
Peritoneal eosinophilia is usually benign and self-limited in CAPD patients, but it becomes protracted in few cases complicated with fungal infection [1,2]. After exclusion of an infectious process, this entity is termed eosinophilic peritoneal serositis, characterized by allergic reaction and non-organismal inflammation [3].
Peritoneal eosinophilia is arbitrarily defined as an absolute eosinophil count of >100/µl [4] or eosinophils >10% of total effluent leukocytes in case of the eosinophil number >40/µl [5]. However, Chan et al. [4] declared that peritoneal eosinophilia should not be considered in patients even with eosinophils more than 15% of peritoneal fluid sediments, especially when total leukocyte count is below 250/µl. In our patient, the diagnosis was overlooked because of the antibiotics used as the first-line treatment for CAPD patients with evidence of peritonitis, and further impeded in the presence of effluent eosinophil count less than 100/µl. Following a series of peritoneal effluent analyses (Figure 2), eosinophils of >10% preceded the elevation of eosinophil count >100/µl for 34 weeks. Therefore we stress the point that an increase in percentage of eosinophils (>10%) in peritoneal effluent is a sensitive marker for early diagnosis of peritoneal eosinophilia and probably best reflects the allergic inflammatory state.
Peritoneal eosinophilia has been hypothesized as an allergic reaction. The offending agents included dialysate additives, air or blood introduced at the time of surgery, constituents in the peritoneal dialysis (PD) catheter, leaching of sterilants or plasticizers from the dialysis bag or tubing, or even mechanical trauma from too large a volume of exchange fluid or from catheter insertion. Accordingly, eosinophilic peritoneal serositis usually appears within 6 months after the start of peritoneal dialysis [4]. Our case had received CAPD treatment for more than 2 years and had been exposed to none of these offending factors recently. When faced with peritoneal eosinophilia, one should further differentiate eosinophilic peritoneal serositis from eosinophilic peritonitis complicated by fungal infection [1,2]. However, repeated effluent cultures for fungi were negative in our patient. Some investigators have proposed peritoneal eosinophilia as a reaction, to confer some immunity against peritonitis [6]. This might be a mechanistic explanation for our case, with evidence of blood eosinophilia and increased plasma IgE, following repeated bacterial peritonitis in the preceding 6 months.
Peritoneal eosinophilia is usually benign and self-limited. It deserves clinical observation without the necessity of antibiotic administration. Based on the allergic mechanism, oral antihistamine is advocated to achieve a sustained resolution in some cases [7]. The oral or i.p. administration of steroid has only been suggested for severe abdominal pain, for hypoalbuminaemia, or to maintain patency of the catheter if PD effluent is markedly turbid [4,8]. The response to loratadine was favourable initially but failed a week later in our patient. Oral prednisolone was added to loratadine on the 8th day of treatment because of progressive hypoalbuminaemia and lower extremity oedema. The combination therapy produced a dramatic improvement and sustained recovery, which corroborated the findings of Thakur et al. [8].
Teaching points
Notes
Supported by an educational grant from
Correspondence and offprint requests to: Dr Der-Cherng Tarng MD, Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112, Taiwan.
References