Case Report

A 37-year-old man complained about progressive right lower-quadrant abdominal pain for 6 months. He had a 7-year-long history of paroxysmal nocturnal hemoglobinuria (PNH) presenting as recurrent abdominal pain with dark urine. His abdominal pain had been assumed to be PNH-associated intestinal ischemia, relieved after transfusion. Recently, computed tomographic (CT) scan revealed parietal thickening and fistula in the right colon, and abdominal abscess with psoas and iliac muscle involvement this time (Figure 1). Colonoscopy showed multiple ulcers and pseudopolyps in the right colon (Figure 2). Laparoscopic right hemicolectomy was performed. Postoperative pathology found transmural and discrete ulcerations, neutrophil infiltration with features of crypt abscess, and the formation of pseudopolyps, which was compatible with Crohn disease (CD).

FIGURE 1. Computed tomographic scan revealed parietal thickening and fistula in the right colon and abdominal abscess.

FIGURE 2. Colonoscopy showed multiple ulcers and pseudopolyps in the right colon.

Discussion

PNH is a rare acquired disease characterized by intravascular hemolysis, bone marrow aplasia, and thrombosis. Some patients suffer from recurrent abdominal pain, secondary to intestinal microthrombi and ischemia (Hillmen, Lewis, Bessler, Luzzatto, & Dacie, 1995). Several studies showed endoscopic images of PNH-associated intestinal ischemia conforming to typical manifestation of intestinal ischemia, and characterized by congestive and edematous mucosa with multiple erosions and ulcerations (Torres, Benedicte, Noel, Notteghem, & Colombel, 2010). However, our patient manifested with intestinal fistula, abdominal abscess, and multiple intestinal pseudopolyps, entirely different from previous PNH cases. The patient was finally diagnosed as having CD based on the postoperative histological result.

The differential diagnosis between CD and intestinal ischemia is difficult. For example, a PNH patient with complication of intestinal ischemia was misdiagnosed as CD with poor response to all modes of CD treatment (Slvakumaran, Hoyles, Hunter, & Middleton, 1999). In our study, the patient's initial presentation was compatible with PNH-associated intestinal ischemia. However, the alterative diagnosis of CD finally rested on the clinical, endoscopic, and histological findings. Although several studies revealed that intestinal ischemia might be a potential pathogenesis for CD (Angerson, Allison, Baxter, & Russell, 1993; Anthony, Dhillon, Pounder, & Wakefield, 1997), the causal relationship between PNH and CD was unclear. To our knowledge, this is the first case report of PNH complicated with CD.

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