Multidisciplinary Management of Ultra-Rare Multifocal Epithelioid Hemangioendothelioma with Symptomatic Tibial Involvement: A Case Report

Objective: Epithelioid hemangioendothelioma (EHE) is an ultra-rare vascular neoplasm with an unpredictable clinical course and no established treatment algorithm. Osseous involvement is uncommon, and evidence for radiotherapy in bone EHE is limited. We report a patient in whom an initially asymptomatic tibial focus became painful several years after detection and was managed with orthopedic reconstruction and symptom-directed radiotherapy. Case Report: A 69-year-old woman had multiple pulmonary and hepatic lesions and pathological uptake in the proximal left tibia detected incidentally in 2021; she initially declined biopsy. Right pulmonary wedge resection in 2023 established the diagnosis of EHE, and pazopanib was started in 2025. In December 2025, she developed worsening left knee pain and impaired mobility; magnetic resonance imaging showed a 45 × 35 mm proximal tibial mass, and biopsy confirmed EHE. After orthopedic reconstruction, persistent pain prompted palliative radiotherapy using volumetric modulated arc therapy at 30 Gy in 10 fractions on March 9-20, 2026. Results: Pain decreased approximately one week after radiotherapy completion. A subsequent surgical-site infection during pazopanib treatment required reoperation on September 15, 2026; its relationship to radiotherapy could not be established. Validated pain scores, analgesic data, post-radiotherapy imaging, and graded toxicity were unavailable, precluding standardized response assessment and attribution of an independent radiotherapy effect. Conclusion: An initially asymptomatic osseous focus in multifocal EHE may later become a significant clinical problem. Pain improvement after radiotherapy in a patient who also underwent orthopedic intervention does not establish the independent efficacy of irradiation. Standardized pain, toxicity, and local control reporting is needed to clarify its role.