#00064954

18-year-old male with history of B-Acute Lymphoblastic Leukemia(B-ALL) treated with DFCI 11-001(Dana-Farber Cancer Institute Acute Lymphoblastic Leukemia (ALL) Consortium Protocol 11-001), and adrenal insufficiency who presented with testicular swelling for 2 weeks, left more than right, about 11 months after last chemotherapy. Subsequent bone marrow biopsy and flow cytometry were normal. Open biopsy of left and right testes was done. [Panel A,B- right testicular biopsy H&E showing neoplastic cells and fibrotic change; Panel C,D,E,F,G and H showing CD34+, TdT+, PAX5+, CD19+, CD79a+ and CD20 + respectively.]   This immunohistochemical profile, together with the patient’s clinical history, is consistent with B-ALL relapse. The frequency of isolated testicular relapse in B-ALL has shown a decline over time, yet maintaining a vigilant level of suspicion is crucial when B-ALL remission patients manifest testicular swelling, especially when no abnormalities were observed on bone marrow biopsy by morphology and flow cytometry immunophenotyping studies.