Un cas rare d’une péritonite hématologique compliquant une myélofibrose secondaire.

Résumé

La péritonite est l’une des complications fréquentes de la dialyse péritonéale. Son diagnostic repose sur des signes cliniques (douleur, effluent trouble), une hyperleucocytose intrapéritonéale (> 0,1×109/L avec plus de 50 % de polynucléaires), et/ou une culture positive. Bien que la majorité des péritonites soient d’origine infectieuse, il existe des formes d’origine non infectieuse qui peuvent entrainer un usage inapproprié d’antibiotiques et un retard diagnostic. Nous rapportons le cas d’un patient de 78 ans, atteint d’une hémopathie complexe qui associait hémoglobinurie paroxystique nocturne, malgré un traitement par ravulizumab, et une thrombocytémie essentielle transformée en myélofibrose. Après initiation d’un traitement par dialyse péritonéale, il a présenté un liquide de dialyse parfois trouble et riche en leucocytes (jusqu’à 0,442 ×109/L), aucune infection n’a été mise en évidence (cultures et PCR ADN16S négatives, CRP modérée, absence de cellules atypiques). L’origine de l’hyperleucocytose intra-péritonéale a été attribuée à l’hyperleucocytose sanguine liée à la myélofibrose. L’évolution clinique a été défavorable, menant à une prise en charge palliative.
Ce cas illustre la difficulté de la prise en charge de cette complication chez les patients en dialyse péritonéale. Bien que le diagnostic de première intention, par argument de fréquence, soit la péritonite infectieuse, il parait nécessaire d’évoquer les différents diagnostics différentiels en cas de péritonite à culture négative et notamment les différentes causes hématologiques (leucémies, lymphomes, myélofibrose). Cependant, les formes avec prédominance de polynucléaires neutrophiles dans le dialysat peuvent simuler une infection. L’absence de fièvre, de CRP élevée, et une corrélation entre hyperleucocytose sanguine et péritonéale devraient aider au diagnostic différentiel. L’immunophénotypage ou la biologie moléculaire dans le dialysat pourrait affiner le diagnostic. Ce cas met en évidence une cause possible de péritonite stérile, la myélofibrose avec hyperleucocytose, et invite à adapter les recommandations à des situations cliniques de plus en plus complexes.

INTRODUCTION

Peritoneal dialysis is one of the techniques used for renal replacement therapy. It is commonly used in France, although much less than hemodialysis[1]. Like any technique, it is not without complications, the most well-known of which is peritonitis[2][3].

The diagnosis of peritonitis is based on the presence of at least two of the following[4]:

- clinical features consistent with peritonitis, i.e., abdominal pain or cloudy dialysis effluent;

- a white blood cell count in dialysis effluent > 100/µL or > 0.1 × 10⁹/L (after a stasis time of at least 2 hours), with > 50% polymorphonuclear leukocytes (PMNs);

- a positive culture in the dialysis effluent.

The majority of peritonitis cases are infectious in origin, but other etiologies must be considered and investigated[5][6][7][8]. Signs of peritonitis are usually interpreted as infectious in origin to avoid delays in treatment, which can lead to significant morbidity and mortality. However, this can lead to complications, including the excessive use of antibiotics, which risks altering the bacterial ecology and promoting antibiotic resistance; it can also lead to delayed management of the underlying disease (which may be iatrogenic, an allergy, an oncological or hematological condition, or a surgical pathology). The recommendations for managing peritonitis [[4]] emphasize the need to initiate antibiotics promptly, given the potential severity of the infection; however, this recommendation must be qualified, and management must be adapted on a case-by-case basis.

Nephrology patients are often elderly, have multiple pathologies, and are on multiple medications. This presents us with a complex pattern of complications and observations, particularly in oncological and hematological contexts.

We report here a case of non-infectious peritonitis manifesting as sometimes cloudy peritoneal dialysis effluent, associated with an excess of intraperitoneal white blood cells secondary to blood hyperleukocytosis, itself a consequence of a hematological disease.

CASE PRESENTATION

A 78-year-old man developed stage V chronic kidney disease in the context of paroxysmal nocturnal hemoglobinuria that progressed despite treatment with ravulizumab (Ultomiris®, Alexion Pharma France) and then eculizumab (Soliris®, Alexion Pharma France). He had a history of paroxysmal nocturnal hemoglobinuria and also essential thrombocythemia with a cytogenetic diagnosis of MPL W515L and associated DNMT3A mutation, which secondarily transformed into myelofibrosis and had been treated with hydroxyurea (Hydrea®) and ruxolitinib (Jakavi®) since 2023 (with known hyperleukocytosis at 30G/L). He also presented with flutter and high blood pressure.

He began emergency extrarenal purification by hemodialysis after placement of a right internal jugular tunneled catheter on October 28, 2024, followed by peritoneal dialysis on January 6, 2025 (after placement of a peritoneal dialysis catheter accompanied by treatment for an inguinal hernia on December 9, 2024). His protocol included a short exchange (4 hours) of isotonic solution (Physioneal 40® with 1.36% glucose, Baxter International Inc.) and a long exchange of hypertonic solution (Extraneal®, Baxter International Inc.) for the rest of the nycthemeral cycle. The protocol was adapted to the patient's needs, his residual renal function, and the availability of registered nurses.

On January 13, 2025, his nurses reported difficulty with drainage and that the patient was suffering from abdominal pain. He was admitted to the day hospital and underwent an exchange, which restored the drainage fluid to a clear state. However, cytological examination revealed a white blood cell count of 0.139 × 10⁹/L, with 53% polynuclear cells. Blood tests showed a CRP of 8 mg/L, a hemoglobin level of 9 g/dL, and a white blood cell count of 63 × 10⁹/L, with 36 × 10⁹/L of polynuclear cells.

Bacteriological samples of dialysis fluid and blood were cultured. The ASP found the catheter in place but with an accumulation of fecal matter. Because of the possibility of infectious peritonitis related to peritoneal dialysis, he was given empirical intraperitoneal antibiotic treatment with cefazolin and ceftazidime (in accordance with the Toulouse University Hospital protocol). Given his stable clinical condition, the patient was discharged home.

On January 14, 2025, he was re-evaluated in consultation due to persistent abdominal pain and slightly cloudy drainage fluid. Cytological examination revealed an elevated white blood cell count of 0.197 × 10⁹/L, with 51% polymorphonuclear cells. He was admitted to the nephrology department on the same day.

Physical examination on admission showed no fever, a blood pressure of 160/80, and a heart rate of 70 bpm. Cardiopulmonary auscultation was normal. The abdomen was tender with no guarding or contracture. The results of laboratory and imaging tests after admission were as follows:

-Cytological analysis of the dialysis fluid revealed a white blood cell count of 0.201 × 10⁹/L, with 29 % polynuclear cells.

- The effluent culture was negative, as was the 16S DNA (bacterial DNA by PCR),

-Blood te sts revealed a CRP of 4.4 mg/L, a hemoglobin level of 8.7 g/dL, and a white blood cell count of 67 × 10⁹/L with a predominance of PNN.

-All blood cultures were negative.

-Computed tomography revealed parietal thickening of the colon associated with infiltration of peritoneal fat.

Given the results and despite no increase in CRP, a diagnosis of colitis without peritonitis was made, prompting a change in antibiotic therapy to intravenous tazocillin for a total duration of 7 days. The patient was discharged home.

On February 3, due to persistent asthenia, tests were performed to assess the progression of the patient's hematological disease:

-A myelogram showed poor

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