Venous malformations, previously called cavernous haemangiomas, are categorized as slow-fiow vascular malformations. A few cases of venous malformations with a dermatomal distribution have been described previously (1^). We call this clinical entity "zosteriform venous malformations", while the terms "zosteriform cavernous haemangiomas" and "unilateral dermatomal cavernous haemangiomatosis" were previously used to describe the lesions. We report here a case of venous malformations with a unilateral C6 dermatomal distribution and summarize the available literature regarding venous malformations with this characteristic distribution pattern. CASE REPORTA 58-year-old Japanese man presented with a 5-year history of two gradually-enlarging, bluish nodular lesions involving the right upper extremity. The patient was otherwise healthy. No pain or pruritus was noted. The lesions were sessile, spherical, smooth-surfaced, and were located on the lateral flexor surface of the right forearm and the radial aspect of the wrist joint (Fig. 1). They measured 35 mm and 25 mm in diameter, respectively. They were distributed along the C6 dermatome. No tenderness was noted, but palpable pulsations and surrounding dilated veins were found on the wrist lesion. Neither hyperhidrosis over the lesions nor hypertrophy of the right arm was detected. The patient's family history was negative for similar lesions. Laboratory examinations were unremarkable. No visceral masses were detected in imaging studies, including computed tomography, esophagogastroduodenoscopy, and colonoscopy.Magnetic resonance imaging (MRI) revealed two intramuscular masses, both measuring approximately 30 mm in diameter, in addition to two peripheral ones corresponding to the skin lesions (Fig. 2). All four lesions were oriented along the long axis of the extremity, strictly following radial neurovascular distribution: two intramuscular lesions followed the deep branch of the radial nerve that runs along the radius, while two superficial lesions followed the superficial branch of the radial nerve. These masses had signal intensities similar to that of skeletal muscle Fig. 1. Pedunculated, spherical, smoothly surfaced, bluish tumours on the lateral flexor surface of the right forearm and the radial aspect of the wrist joint, distributed along the C6 dermatome.