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Gangrenous appendicitis in a patient with severe congenital neutropenia

Severe congenital neutropenia (SCN) is a rare congenital hematological disorder usually caused by heterozygous mutations in ELANE, encoding neutrophil elastase. Before granulocyte colony-stimulating factor (G-CSF) is used, patients with SCN have absolute neutrophil count (ANC) <0.5 9 10/L and frequently develop serious infections including mouth ulcers (80%), pneumonia (49%), abscesses (19%), sepsis (17%), cellulitis (12%), and peritonitis (3%). Here, we report the case of a 12-year-old girl with SCN. The diagnosis of SCN had been established soon after birth based on family history: father with SCN, normal white blood cell count without neutrophils, normocellular marrow with an extremely decreased number of myeloid progenitor cells, and the genetic characteristics of ELANE mutation. ANC was consistently <50 cells/lL and did not increase even during infections. G-CSF had never been used due to parent refusal. The patient had frequent febrile episodes, complicated by severe oral ulcers, requiring 1–2 week i.v. antibiotics. The patient was admitted to hospital because of a 7 day episode of mild but persistent pain in the right lower quadrant of the abdomen, accompanied by fever and oral ulcers, despite i.v. antibiotic treatment with piperacillin-tazobactam for 4 days as an outpatient. Abdominal examination indicated local, mild tenderness and rebound without guarding at McBurney’s point. On laboratory testing, white blood cell count was 4970/lL with 1.8% neutrophils, 8.3% eosinophils, 0.9% basophils, 41.3% monocytes, and 47.7% lymphocytes and C-reactive protein was 13.1 mg/dL. Contrast-enhanced computed tomography showed a swollen appendix with wall thickening and fluid accumulation in the lumen, along with pericecal fat stranding (Fig. 1a,b). Based on these findings, a diagnosis of acute appendicitis was made and surgical appendectomy was performed. During open surgery, the non-perforated, gangrenous appendix was resected. On macroscopic examination, the appendix had diffused thickening of the appendix wall and purple discoloration on the serosal surface. Histologically, the mucosa was partly destroyed and necrosed, and there was extensive inflammatory cell infiltration extending throughout the mucosa, submucosa, and muscularis and into the subserous layer, indicating gangrenous appendicitis (Fig. 1c). This inflammatory infiltrate predominantly consisted of a large number of lymphocytes and eosinophils, although neutrophils were virtually absent (Fig. 1d). Acute appendicitis is a suppurative inflammatory process of the vermiform appendix and is characterized by infiltration of neutrophils into the mucosa and submucosa. SCN is a rare disorder characterized by severe neutropenia from birth and sometimes presents in an atypical inflammatory fashion because of lack of adequate inflammatory response. The present SCN patient developed acute gangrenous appendix presenting with non-progressive, mild but persistent symptoms and signs in the lower abdomen. The atypical presentations of appendicitis were probably due to the lack of neutrophil inflammation. Such atypical presentations of appendicitis have sometimes been observed in patients with hematologic malignancies during chemotherapy. Similar to the present case, recognition of appendicitis may be difficult in such patients because therapy-induced neutropenia and multiple medications cause an altered inflammatory response. Even in therapy-induced neutropenic patients, however, true appendicitis predominantly consists of neutrophilic infiltration, which was not present in the current case. Therefore, patients with SCN possibly develop acute gangrenous appendicitis with an indolent clinical course.