Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 10 5 2026 05 04 229 232 Mitra Ardakani Moghadam Pediatric Hematology and Oncology Department, Tehran University of Medical Sciences, Tehran, Iran. Maryam Noory Children’s Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran. Arghavan Tajalli Pediatric Hematology and Oncology Department, Tehran University of Medical Sciences, Tehran, Iran. Mohammad Kaji Yazdi Pediatric Hematology and Oncology Department, Tehran University of Medical Sciences, Tehran, Iran. 2025 12 15 2025 12 20 Acute lymphocytic leukemia (ALL) is a prevalent cancer in pediatrics. The cutaneous manifestation known as leukemia cutis is an unusual presentation of ALL, and patients with this manifestation have a poor prognosis. In this report, we present a 3-yearold boy who was referred to our clinic with cutaneous manifestations of ALL and responded well to treatment. A 3-year-old male patient was referred to our clinic for swelling in the left posterior thoracic region. The child’s parents reported an observable bulging in the abdominal area. Ultrasonography revealed splenomegaly and a hypoechoic mass measuring 11 mm × 8 mm in the anterior superior cortex of the right kidney. Laboratory studies indicated leukocytosis. Imaging findings suggested potential metastatic liver involvement, with a less probable diagnosis of secondary non-Hodgkin lymphoma (NHL). Bone marrow aspiration (BMA) and biopsy of the thoracic lesion were performed. The BMA confirmed a diagnosis of acute pre-B cell lymphoblastic leukemia (ALL), and the cutaneous biopsy indicated infiltration by leukemic cells. The patient was initiated on a standard treatment regimen, to which he responded well. Leukemia cutis is rare in children and may present as unresponsive swelling. Pediatricians should consider it when standard treatments fail. https://crcp.tums.ac.ir/index.php/crcp/article/view/1152 https://crcp.tums.ac.ir/index.php/crcp/article/download/1152/752