Purpose <p>Simple bone cysts (SBCs) involving the mandibular ramus in pediatric patients are exceedingly rare and present a notable diagnostic dilemma, owing to their radiological resemblance to more aggressive jaw pathologies such as odontogenic keratocyst (OKC) and ameloblastoma. The potential for misdiagnosis may result in unnecessarily aggressive surgical intervention, particularly in the pediatric population where conservative management is paramount. This report aims to illustrate the diagnostic complexities and management considerations associated with a large, multilocular SBC of the mandibular ramus in a child, highlighting the imperative for a systematic and judicious diagnostic approach.</p> Case report <p>We present the case of a 13-year-old girl with mild swelling of the left mandibular ramus. Cone beam computed tomography revealed a multilocular radiolucent lesion associated with an impacted second molar, raising initial concern for an odontogenic tumor. Aspiration produced straw-colored fluid, while surgical exploration demonstrated an empty osseous cavity. Histopathological examination confirmed the diagnosis of SBC. The lesion was managed with conservative curettage and extraction of the impacted tooth, resulting in uneventful recovery and radiographic evidence of satisfactory bone regeneration at one-year follow-up.</p> Conclusion <p>This case underscores the critical importance of considering SBC in the differential diagnosis of multilocular radiolucencies of the pediatric mandibular ramus. Careful integration of clinical, radiological, and histopathological data is essential to avoid unwarranted aggressive treatment and to optimize patient outcomes. This report contributes to the limited literature on ramus SBCs in children and reinforces the value of a conservative therapeutic strategy in such presentations.</p>