Background. Actinomycosis (ACM) is a rare infectious granulomatous disease caused by Actinomyces, a Grampositive, filamentous, saprophytic bacteria. There are several types of pediatric ACM, such as orocervicofacial (55%) and other less common forms: abdominopelvic and thoracic. We report a case of a 16-year-old who presented with abdominal ACM in the setting of acute appendicitis. After the case report, we provide a short literature review of pediatric appendicular ACM cases published.

Case. A 16-year-old boy presented with nausea, vomiting, pain in the upper part of the abdomen and fever (37.5°C) lasting for 24 hours. On physical examination, the patient`s epigastrium and lower right abdominal quadrant were tender. White cell count and C-reactive protein (CRP) were elevated at 16,300/μL and 48.6mg/L respectively. Ultrasonography (US) showed appendicolith and edema of the appendiceal wall, focally with stratification as well as periappendiceal inflammation. The patient underwent a classic appendectomy, and the postoperative course was without complications. Histopathological analysis showed diffuse transmural neutrophilic infiltration of the appendix, focally with areas of necrosis and abscesses. There were numerous brightly eosinophilic colonies made of filamentous bacteria, located predominantly in submucosa. Special stains Grocott-Gomori`s Methenamine Silver and Gram were positive and a diagnosis of ACM was made.

Conclusions. Although appendicitis is very common in the general population, appendicitis associated with ACM is very rare, accounting for 0.02% - 0.06%, especially in the pediatric population. Diagnosis can be very challenging because they usually present with non-specific symptoms, and can form masses that mimic malignancies. Although rare, clinicians and pathologists should be aware of this entity. Satisfactory results and complete cure are achieved with adequate antibiotic therapy and surgery. In most cases, if there are no associated diseases, early and accurate diagnosis ensure an excellent prognosis.

Keywords: actinomycosis, appendix, children