Abstract
INTRODUCTION: Arteriovenous malformations (AVMs) are rare congenital vascular abnormalities involving direct connections between arteries and veins, bypassing capillaries. While they can occur throughout the body, AVMs in the forearm are uncommon, representing a diagnostic and therapeutic challenge when they produce symptoms, such as neurovascular compressions, such as unspecified swelling or mass, throbbing pain, localized or radiating tingling, and numbness. These lesions often remain asymptomatic until adolescence, when growth spurts and hormonal changes can trigger enlargement and clinical symptoms. CASE REPORT: We describe a 15-year-old female with a 2-year history of an enlarging, non-painful mass in her right forearm, accompanied by tingling and numbness in the ulnar nerve distribution of her hand. On examination, a subcutaneous, non-tender swelling extending from her elbow to the distal forearm without overlying skin changes. MRI showed a complex vascular lesion within the intramuscular plane, mass effect on the extensor digitorum and extensor digiti minimi muscles compressing the ulnar nerve, and suspecting an AVM.Given the lesion's proximity to the ulnar nerve and the disturbing symptoms in the right dominant hand, surgical intervention was planned. An excision of the localized swelling was performed under a tourniquet control, with precise dissection to protect the epineurium and vasa nervosum of the ulnar nerve, however since no frank bleeding was observed post-excision, no vascular anastomosis or repair was performed. Histolo-pathology of the soft tissue sample confirmed an AVM consisting of dilated vascular channels.The patient's recovery was smooth, with complete symptomatic relief and no evidence of recurrence at 1-year follow-up. CONCLUSION: This case underscores the need to consider AVMs as an important differential in adolescent patients presenting with progressively enlarging soft tissue masses and neurovascular symptoms not amenable to common etiology, such as radiculopathy, epicondylitis, and trauma. MRI provides essential insight into lesion extent and guides surgical planning, which remains the primary treatment modality for symptomatic AVMs causing nerve compression. Although recurrence is a common risk, especially in pediatric patients, careful excision and follow-up are key to reducing this risk and ensuring better long-term outcomes. This case reinforces the importance of multidisciplinary care involving radiology, vascular surgery, and pathology for effective diagnosis, and management of occult symptomatic vascular malformations in adolescents.