Early cutis marmorata telangiectatica congenita masquerading as ulcerated retiform purpura: a diagnostic trap

Cutis marmorata telangiectatica congenita (CMTC) is a rare congenital cutaneous vascular anomaly with a reticular marbled erythematous pattern, which can result in isolated benign skin lesions or less commonly be associated with systemic anomalies. Occasionally, the characteristic pattern of CMTC lesions is masked on initial presentation, creating a diagnostic conundrum that can result in unnecessary workups to rule out vasculopathy. We present the case of a female newborn with a red‐blue ulcerated skin lesion on the right leg and foot, which initially appeared as retiform purpura but evolved to exhibit the mottled pattern of CMTC by 5 days of age. Clinicians must be made aware of this potential diagnostic trap in early CMTC to avoid invasive skin biopsies and unnecessary laboratory testing in neonates.