Acquired progressive lymphangioma.

A 5-year-old Japanese boy, who developed dark brown, erythematous lesions (two separate lesions) on his face, scalp, and left upper arm within 2 years, was reported. Biopsy specimens revealed many dilated channels lined by a single layer of endothelial cells without obvious atypicality throughout the dermis. These channels split collagen bundles, giving a "dissection of collagen" appearance. From these clinical and histopathologic findings, we have diagnosed these lesions as acquired progressive lymphangioma. Our patient is the youngest reported patient in the literature, and we were interested in that the two lesions developed separately following previous trauma and they had the tendency to regress following oral prednisolone therapy.