Arteriovenous Malformation Involving Digital Nerves in the Hand: Case Report and Review of the Literature.

Intraneural vascular anomalies are rarely encountered specimens as these are not commonly resected. To the best of our knowledge, this is the first report of the histologic findings in an arteriovenous malformation (AVM) within a digital nerve. We report a rare case of an 18-year-old man with a painful mass in the left hand and middle finger who was referred to our hospital for a treatment strategy consultation. According to Schobinger's clinical classification, the patient was diagnosed with Early-Stage 3 AVMs of the left hand and was followed up for approximately 1 year. Due to increasing pain and dark purple discoloration of the finger, the AVM on the left middle finger was removed en bloc, including the skin, subcutaneous fat, and digital nerve, leaving the tendon and the periosteum. Histology revealed the abnormal vasculature of the AVM within the digital nerve and adjacent subcutaneous fibroadipose tissue. Histologically, two patterns of nerve involvement were recognized: arterioles that pushed into the nerve fascicle in a non-destructive manner, compressing the perineurium, and numerous microvessels in the endoneurium surrounded by microvascular proliferation found on the outside of the perineurium. The presence of intraneural abnormal vessels suggested that one cause of AVM pain was neuropathic.