Mucosal appendicitis: How can it be differentiated from nonappendicitis?

Objectives: Mucosal appendicitis is defined by neutrophilic infiltration limited to the mucosa, with no transmural invasion; it is currently a controversial entity. The aim of our study was to determine whether mucosal appendicitis represents an early stage of acute appendicitis (AA) or should be considered a negative appendectomy.

Methods: A retrospective study was performed of children with suspected AA who underwent surgical treatment between 2017 and 2020. The participants were divided into 2 groups according to histologic appendiceal findings: mucosal appendicitis (MA) and negative appendicitis (NA). Demographic, clinical, ultrasound, and laboratory features were compared between the groups.

Results: A total of 1269 patients with suspected appendicitis in whom appendectomy was performed were included, with a median age of 10.5 years. Mucosal appendiceal inflammation was histologically confirmed in 30 cases (MA group), while no inflammation or other pathologic findings were observed in 25 cases (NA group), with no differences in demographic, clinical, or ultrasound features between the groups. Those in the MA group presented with significantly higher leukocyte and neutrophil counts and higher neutrophil to lymphocyte ratios (NLRs) than those in the NA group (P < .001). The NLR was the parameter with the highest area under the curve (0.736) for the diagnosis of MA. A cutoff of 3.20 was established, with a maximum sensitivity and specificity of 62.5% and 78.9%, respectively.

Conclusions: Mucosal appendicitis presents with laboratory and histologic inflammatory features that can be distinguished from nonappendicitis and should therefore be considered a pathologic entity within the spectrum of AA. Preoperative leukocyte and neutrophil counts and NLRs may help reduce the number of negative appendectomies.