A 48-year-old Hispanic man presented to our clinic with multiple, bright red, firm nodules limited to the right side of the scalp (Fig. 1). The patient had first noted a lesion 6 months previously, and complained of mild associated pruritus and ease of bleeding. The first lesion developed at the exact site at which the patient had accidentally hit his head against a filing cabinet 2 years previously. The trauma had been associated with significant bleeding, which required more sutures than expected. In a magnetic resonance image, the initial nodule was visualized and, because of its firm consistency, the diagnosis of a lipoma was made. Surgical excision of the tumor was attempted, but was complicated by significant bleeding, which required extensive electrocoagulation. Shortly thereafter, multiple new lesions slowly began to develop around the original nodule. In addition, the patient complained of new-onset migraine headaches.
On physical examination, the right side of the patient's scalp showed multiple, erythematous, firm papules and nodules measuring 0.5–2.5 cm in diameter. These were slightly alopecic, and the largest and earliest tumor was pulsatile. There was no associated lymphadenopathy or peripheral eosinophilia. On angiography, an arteriovenous malformation was detected. Specifically, branches from the occipital arteries bilaterally appeared to feed the malformation (Fig. 2). Skin biopsy of one of the nodules revealed lobular proliferations of capillary-sized vessels around larger central vessels, with a mild perivascular infiltrate of lymphocytes and eosinophils in the dermis. The larger vessels were lined by characteristic “hobnail” endothelial cells, which protruded into the lumen (Fig. 3). As this vascular anomaly was thought to underlie his skin lesion, the patient was treated with embolization using polyvinyl alcohol particles and fiber coils, which resulted in increased pallor of the lesions, a greater than 50% decrease in size, decreased pulsatility, and resolution of his migraine headaches. Six months after this successful procedure, no new lesions had developed. Presently, the patient is opting to defer further treatment in the hope that the lesions will resolve entirely. A second endovascular treatment with polyvinyl alcohol particles and acrylic glue is pending based on the course of his disease.