Abstract
This case presents an 8-year-old girl diagnosed with B-cell acute lymphoblastic leukemia (B-ALL), who relapsed after 3 years of treatment and 1 year of complete remission, with an unusual extramedullary relapse in the ovary. Ovarian relapse of B-ALL is extremely rare in children, making this case noteworthy in scientific literature. The patient had an initial diagnosis of B-ALL with a deletion of chromosome 12, a genetic alteration previously associated with the ETV6-RUNX1 fusion gene, which is typically linked to a favorable prognosis but also carries a 20% risk of late relapse. The relapse was initially asymptomatic and went undetected until clinical symptoms of pelvic pain appeared. Imaging with pelvic ultrasound confirmed the ovarian involvement. The relapse was treated with standard chemotherapy protocols for B-ALL, resulting in a partial response. This case underscores the importance of considering extramedullary relapse in the differential diagnosis for pediatric ALL patients who present with atypical symptoms after remission. It also suggests that routine pelvic ultrasound could be a useful tool for early detection of ovarian and other extramedullary relapses, which are often associated with bone marrow relapse. The main take-away from this case is the necessity for vigilant follow-up, including targeted imaging, in ALL patient's post-remission to ensure early identification of extramedullary relapses, which can otherwise be easily overlooked. The presence of chromosome 12 deletion and its association with late relapse highlights the need for ongoing surveillance even in patients with initial favorable genetic abnormalities.