B-Lymphoblastic Lymphoma Presenting With a Facial Mass as the Initial Symptom.

This case report describes a 12-year-old girl with B-lymphoblastic lymphoma (B-LBL) initially presenting as a painless swelling on the right nose and cheek. The lesion began on the right nasal ala, expanded to the cheek, and transiently responded to oral corticosteroids. Physical examination and ultrasound initially suggested an inflammatory process. Diagnosis was confirmed by skin biopsy, revealing dense proliferation of immature B-cells positive for CD79a, PAX5, and TdT, with a high Ki67 index. Staging PET/CT demonstrated extensive cutaneous, nodal, and extranodal involvement, classifying the disease as stage III. Bone marrow aspiration showed no significant lymphoblastic infiltration. The patient was treated per an intermediate-risk pediatric lymphoma protocol, achieving complete resolution of the facial swelling after 3 weeks of induction chemotherapy. This case highlights that B-LBL is a highly aggressive lymphoma, most common in children, often involving the head and neck skin, and is prone to misdiagnosis, thus underscoring the importance of early biopsy and standardized treatment.