Capillary malformations in unusual territory: Klippel–Trénaunay syndrome with penoscrotal involvement

Abstract Klippel–Trénaunay syndrome (KTS) is a rare congenital vascular disorder that typically presents with capillary and venous malformations, limb hypertrophy and, in some cases, lymphatic abnormalities. We report a 3-year-old boy with extensive vascular malformations affecting the left lower limb, predominantly involving the penoscrotal region – an uncommon presentation without systemic involvement. This case illustrates the diagnostic complexity of genitourinary KTS and emphasizes the need for vigilant monitoring, multidisciplinary input and tailored management to reduce complications and improve long-term outcomes.