Tramlines Emerging on a Lower Leg

A 54-year-old diabetic man presented with a linear erythema newly appearing on his right lower inner leg (Picture A). He had a history of repeated tinea pedis, and physical examination revealed the presence of redness on his right fourth toe (Picture B). The “tramline” seemed to originate from the toe, ascending to his inner thigh (Picture C). He was febrile, and laboratory testing showed leukocytosis. Under a diagnosis of acute lymphangitis induced by a diabetic foot infection (the pathogenic organism was unknown), he was treated with oral trimethoprim/sulfamethoxazole. Shortly after the treatment, the striated rash disappeared completely. Acute superficial lymphangitis is typically induced by a cutaneous bacterial infection (1). The differential diagnosis includes erysipelas, cellulitis, superficial thrombophlebitis, and allergic reaction (2), but the characteristic “tramline” appearance may lead us to a correct diagnosis without much difficulty. A diabetic foot infection may be an underlying cause of lower leg lymphangitis in diabetes patients, and physicians need to examine the toes of such patients carefully.