# Vascular bone tumors of the pelvis and extremities: an 18-case clinical and radiological analysis

## TL;DR

This study examines 18 cases of vascular bone tumors in the pelvis and extremities, identifying tumor size and soft tissue components as indicators of malignancy and highlighting poor outcomes for malignant cases.

## Contribution

The study identifies tumor size ≥5.5 cm and soft tissue components as key predictors of malignancy in vascular bone tumors of the pelvis and extremities.

## Key findings

- Soft tissue components were significantly more frequent in malignant tumors (57% vs. 9%).
- Tumor size ≥5.5 cm was associated with malignancy with 85.7% sensitivity and 90.9% specificity.
- Benign tumors had excellent outcomes with curettage, while malignant tumors showed high relapse and mortality rates.

## Abstract

Primary vascular bone tumors are rare, spanning from benign to highly malignant lesions. Pelvic and extremity involvement is uncommon, and differentiation between benign and malignant tumors remains challenging due to overlapping radiological and pathological features. This study aimed to identify imaging predictors of malignancy and evaluate clinical outcomes in vascular bone tumors of the pelvis and extremities.

We retrospectively analyzed 18 patients diagnosed with vascular bone tumors between 2013 and 2024. Tumors were classified as benign (hemangioma, epithelioid hemangioma; n = 11) or malignant (angiosarcoma, epithelioid hemangioendothelioma; n = 7). Demographic, radiological (plain radiographs, MRI, CT), and clinical data were collected. Cortical expansion/destruction, pathological fractures, soft tissue components, and tumor size were assessed. Statistical analysis included Fisher’s exact test, Mann–Whitney U test, Spearman correlation, and ROC analysis to identify predictors of malignancy.

Median age was 41.0 years for benign and 53.0 years for malignant tumors. Soft tissue components were significantly more frequent in malignant tumors (57% vs. 9%, p = 0.025), and tumor size was larger (mean 9.0 cm vs. 3.7 cm, p = 0.001). Cortical expansion, destruction, and pathological fractures did not differ significantly. ROC analysis suggested that larger tumor size (≥ 5.5 cm in this cohort) was associated with malignancy with 85.7% sensitivity and 90.9% specificity (AUC = 0.929, p = 0.003) and should be interpreted as an exploratory finding. All benign tumors underwent intralesional curettage, with no recurrences or complications observed. In contrast, malignant tumors exhibited high rates of relapse and mortality, with only one patient with epithelioid hemangioendothelioma surviving with stable disease at 112 months.

In vascular bone tumors of the pelvis and extremities, the presence of a soft tissue component and tumor size ≥ 5.5 cm are among the most useful radiological features associated with malignancy. While benign lesions generally have excellent outcomes with curettage, malignant tumors are associated with a poor prognosis. Histopathological confirmation remains essential, and larger series are needed to refine diagnostic and prognostic criteria.