Cutaneous Presentation of Pre-B Cell Acute Lymphoblastic Leukemia in a 3-Month-Old Boy.

We present a rare case of leukemia cutis as the sole presenting sign of pre-B cell acute lymphoblastic leukemia in a 3-month-old boy. The patient exhibited a solitary, erythematous scalp nodule without systemic symptoms or abnormal peripheral laboratory findings, ultimately diagnosed via biopsy and treated successfully. This case highlights the importance of early dermatologic evaluation and biopsy in persistent or atypical infant scalp lesions.