Incidental Splenic Leiomyoma in a Child Uncovered During Workup for Eosinophilic Gastroenteritis

Eosinophilic gastroenteritis (EGE) is a rare, heterogeneous inflammatory disorder characterized by eosinophilic infiltration of the gastrointestinal tract in the absence of secondary causes. Clinical presentation is variable and often mimics other gastrointestinal conditions, making diagnosis challenging. Splenic leiomyoma, in contrast, is a rare benign smooth muscle tumor, typically reported in immunocompromised patients. Pediatric cases are exceedingly uncommon. We describe a 9-year-old boy presenting with persistent diarrhea and peripheral blood eosinophilia. Endoscopy showed esophageal furrowing, gastric and colonic erythema, and biopsies demonstrated marked eosinophilic infiltration in multiple gastrointestinal sites, consistent with EGE. During work-up, an abdominal ultrasound identified a well-defined splenic mass. Splenectomy revealed a solitary spindle cell tumor composed of bland smooth muscle fibers, diffusely positive for desmin and smooth muscle actin, and negative for C-Kit, CD34, and S100, confirming the diagnosis of splenic leiomyoma. The coexistence of EGE and splenic leiomyoma in an immunocompetent pediatric patient is highly unusual. While the splenic lesion may represent an incidental finding, its occurrence in a child with an inflammatory gastrointestinal disorder raises the possibility of broader clinical contexts for splenic leiomyoma beyond immunodeficiency. This case expands the clinical spectrum of splenic leiomyoma and underscores the importance of thorough investigation in children with persistent gastrointestinal symptoms. We present the first reported case of EGE associated with an incidental splenic leiomyoma in an immunocompetent child. Documentation of such cases contributes to understanding the spectrum, pathogenesis, and potential associations of this rare tumor.