Localized soft tissue angiomatosis with subsequent development of angiolymphoid hyperplasia with eosinophilia

We report an unusual case of arteriovenous (AV) malformation (localized form of soft tissue angiomatosis): a reaction of angiolymphoid hyperplasia with eosinophilia (ALHE) developed over the lesion of this pre-existing AV malformation. To the best of our knowledge, there is no other report of ALHE in association with a pre-existing bona fide AV malformation. A 71-year-old woman consulted our clinic because a reddish, dome-shaped tumor on her preauricular region, present as a slightly elevated, skin-colored tumor since her childhood, had rapidly enlarged and become more elevated with color change during the preceding two months. The histological features of most of the lesion corresponded to those of soft tissue angiomatosis (localized form). The proliferative vessels underlying the soft tissue angiomatosis streamed out and welled into the dermis with an accompanying prominent inflammatory infiltrate composed of lymphoid cells and eosinophils: these histological features were characteristic of ALHE. The recent abrupt clinical changes in the tumor were considered to represent a reaction to the angiomatosis with development of ALHE.