Deep Intramuscular Vascular Malformations in Pediatric Klippel–Trenaunay Syndrome Mimicking Maffucci Syndrome: A Case Report

ABSTRACT Klippel‐Trenaunay syndrome (KTS) is a rare congenital vascular overgrowth disorder characterized by capillary and venous or lymphatic malformations with limb hypertrophy. Deep intramuscular involvement in children is uncommon and may resemble other vascular‐overgrowth syndromes. We report a 12‐year‐old boy with right lower‐limb swelling since birth, recurrent cellulitis, chronic ulceration and purulent discharge, progressive limb enlargement, and four previous soft‐tissue excisions. Examination showed bilateral nodular ulcerated lesions and vascular skin changes. Laboratory testing demonstrated persistent microcytic anemia and raised inflammatory markers. Doppler ultrasonography identified soft‐tissue hypertrophy, macrodactyly, calcified cavernous vascular lesions, superficial venous dilatation, incompetent perforators, and venous reflux, while deep veins remained patent. Contrast‐enhanced magnetic resonance imaging showed extensive intramuscular malformations involving the gastrocnemius and tibialis muscles without marrow or joint involvement. The calcified lesions initially raised concern for Maffucci syndrome; however, the absence of enchondromas and histopathologic confirmation of benign cavernous vascular malformations supported KTS. Progressive symptomatic masses were treated with surgical debulking, drainage, wound care, and culture‐directed antibiotics. Recovery was uneventful, with continued conservative surveillance. This case shows how combined clinical assessment, Doppler ultrasonography, magnetic resonance imaging, and histopathology can distinguish atypical pediatric KTS from skeletal dysplasias and guide treatment when genetic testing and multidisciplinary vascular services are limited.