Targetoid Skin Lesions in a Child: Acute Hemorrhagic Oedema of Infancy and Its Differential Diagnosis

Acute hemorrhagic oedema of infancy (AHEI) is a cutaneous leukocytoclastic small-vessel vasculitis presenting with localized purpuric large skin plaques that are frequently associated with fever and oedema. It must be promptly differentiated from a number of diseases with similar dermatologic manifestations with potentially severe clinical courses that require adequate monitoring and prompt therapy to avoid the risk of a negative evolution. A 15-month-old girl with a negative personal medical clinical history was admitted for the sudden appearance of petechiae on the soft palate. The patient was moderately febrile during the following two days, with a maximum ear temperature of 38.3 °C. The fever disappeared on the third day, whereas the hemorrhagic rash progressively increased and extended to the limbs, face and auricles associated with a strong oedematous component. Moreover, on the second day of hospitalization, bilateral oedema of the metacarpophalangeal joints with joint pain appeared. The blood and serological tests showed an increase in C-reactive protein concentration (3.58 mg/dL) in the absence of leukocytosis and with a normal platelet count (180,000/mm³). The examination of the peripheral smear showed the presence of some large mononuclear elements with hyperbasophile cytoplasm. No alterations in platelet morphology were evidenced. The skin manifestations progressively diminished and disappeared spontaneously within 3 weeks, leaving no sequelae. Conclusion: This case shows the classic skin lesions of AHEI that require differentiation from those of more severe diseases that need prompt recognition and therapy. In this case, the age of the patient, the lack of systemic involvement and the favorable clinical course without therapy were typical. However, as these patients may present to the emergency department with an impressive clinical picture, the condition must be promptly diagnosed to avoid unnecessary diagnostic procedures and to reassure parents.