Serial cases of vascular anomalies seen as musculoskeletal tumors

Abstract Background Vascular anomalies constitute a heterogeneous spectrum of vascular tumors and vascular malformations that often mimic musculoskeletal neoplasms, particularly when presenting as soft tissue masses. Because conventional MRI may show nonspecific morphology, misclassification is common, and inappropriate biopsy may expose patients to significant bleeding risk. A multimodality imaging strategy incorporating Doppler ultrasound, CT angiography, and time-resolved MR angiography is therefore essential for accurate characterization. This case series reinforces four distinct diagnostic pitfalls and demonstrates how multimodal imaging systematically resolves each misinterpretation. Case presentation Four patients presenting with long-standing soft tissue masses underwent sequential multimodal evaluation after initial MRI findings suggested possible musculoskeletal tumors. In the first case, a 49-year-old woman with a paraspinal mass exhibited ill-defined, T2-hyperintense features that mimicked infiltration; only after CT angiography demonstrated a clear nidus with feeding intercostal arteries and early venous drainage was an arteriovenous malformation confirmed. The second case involved a 14-year-old girl with a forearm lesion showing restricted diffusion, a malignant-appearing dynamic contrast curve, and flow voids on SWI but histopathology revealed a benign vascular tumor, illustrating the limited specificity of functional MRI parameters. The third patient, an 18-year-old woman with a lobulated mass on the second digit, demonstrated well-defined but non-diagnostic MRI morphology; Doppler ultrasound subsequently confirmed internal vascularity and FNAB supported the diagnosis of hemangioma. The final case, a 12-year-old girl with extensive involvement of the calf, ankle, and foot, showed heterogeneous enhancement that simulated malignant infiltration; TRICKS-MRA revealed slow delayed filling consistent with a low-flow malformation, and biopsy confirmed lymphangioma. Across all cases, diagnostic errors were consistently linked to inadequate assessment of vascular flow dynamics. Conclusion Vascular anomalies may closely resemble soft tissue malignancies when assessed with MRI alone. Dynamic and physiologic imaging provides decisive information on flow patterns and vascular architecture, enabling accurate classification and reducing unnecessary biopsy. A standardized, multimodal diagnostic algorithm is essential when evaluating soft tissue masses with atypical or ambiguous MRI features.