Leukemia cutis, a tricky diagnosis: a case report and literature review

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy, typically presenting with systemic symptoms and mediastinal involvement. Leukemia cutis (LC) and renal infiltration are rare, especially at disease onset. A 27-year-old man presented with a solitary scalp lesion without systemic symptoms or hematologic abnormalities. Histopathology revealed a blastoid lymphoid infiltrate with a T-ALL immunophenotype. Two weeks later, laboratory tests showed leukocytosis, lymphocytosis, and renal dysfunction. Imaging revealed a large mediastinal mass, scalp soft tissue involvement, and bilateral renal infiltration. Bone marrow biopsy confirmed T-ALL with a mature phenotype. FISH identified TRAD:NKX2 rearrangement and CDKN2AB deletion. The patient received three cycles of pediatric-inspired chemotherapy, achieving complete molecular remission and resolution of extramedullary disease. He subsequently underwent allogeneic hematopoietic stem cell transplantation (HSCT) from an HLA-matched sibling. Post-transplant complications included febrile neutropenia and mucositis. On day +100, he remained in minimal residual disease (MRD)-negative remission. This case illustrates a rare presentation of T-ALL with isolated skin involvement and renal infiltration at diagnosis, highlighting the importance of early biopsy and immunophenotyping of atypical skin lesions. Intensive chemotherapy followed by HSCT represents a viable strategy for young adults with high-risk T-ALL and extramedullary disease.