When a Simple Rash Unmasks a Systemic Crisis: Persistent Inflammatory Skin Lesions Leading to the Diagnosis of Infantile Acute Leukemia

Skin manifestations can be an early but often overlooked sign of systemic malignancy in infancy. We report the case of an eight month old male infant who presented with persistent napkin dermatitis and progressive nodular skin lesions, ultimately leading to the diagnosis of acute leukemia with cutaneous involvement. The child initially developed a diaper area rash that was treated as napkin dermatitis with standard measures but failed to improve and progressively worsened. Weeks later, firm nodular lesions appeared over the hands and forearms, accompanied by pallor, low grade fever, reduced feeding, and increased sleepiness. Physical examination revealed severe diaper dermatitis, multiple non tender nodular skin lesions, pallor, hepatosplenomegaly, and faint bruising. Initial laboratory evaluation showed marked anemia, thrombocytopenia, and leukocytosis with circulating immature cells. Peripheral blood smear raised concern for acute leukemia. Bone marrow aspiration and biopsy confirmed acute leukemia with extensive blast infiltration. Skin biopsy from a nodular lesion demonstrated dermal infiltration by malignant cells, confirming leukemia cutis. Imaging revealed hepatosplenomegaly without focal lesions or evidence of infection. Infectious causes of the skin findings were excluded. Management focused on stabilization, supportive care, and early coordination with pediatric hematology. The infant received blood product support and empiric antibiotics while diagnostic evaluation was completed. Given the confirmed diagnosis and the need for specialized therapy, the patient was transferred to a tertiary pediatric oncology center for definitive management. This case highlights the importance of recognizing persistent or atypical skin findings in infants as potential indicators of serious systemic disease. Failure of common conditions such as diaper dermatitis to respond to standard therapy, especially when accompanied by systemic signs, should prompt thorough evaluation. Early recognition of leukemia cutis can shorten diagnostic delay and improve clinical outcomes in infantile acute leukemia.