Arteriovenous Hemangioma of Foot

Case History: 38-year-old Asian male presented with complaint of left forefoot swelling for seven years associated with dull and vague pain. He further noticed gradual increase in size with continued activity. He denied recent or remote trauma with unremarkable medical history. On physical exam, a nontender soft tissue prominence was noted in 2^nd web space of left foot, predominantly in the plantar aspect of the foot. There was no evidence cellulitis. Radiographic examination of the left foot was negative except for the presence of mildly prominent soft tissue over the forefoot dorsum (Figure 1). Further magnetic resonance (MR) imaging was subsequently performed for characterization of lesion.

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Figure 1. Plain radiograph of left foot (antero-posterior view) showing subtle soft tissue radio-opacity between proximal phalanges of second web space of sole (arrow).

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Figure 2. T2 weighted axial image shows mixed intensity lesion (hyperintense on T2W containing multiple flow voids - arrow within and few low signal areas) in intramuscular plane of sole.

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Figure 3. T1 weighted axial image shows ill-defined lobulated hypointense lesion (arrow) extension in both dorsal and plantar in second web space.

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Figure 4. Axial T2-weighted image with fat suppression shows lobulated hyperintense mass lesion with scattered hypointensities within it representing clots, hemosiderin, smooth muscle and dense fibrous tissue (arrow).

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Figure 5. A, pre-contrast and B, post-contrast. Fat-suppressed T1-weighted image following gadolinium administration reveals a mild increase in homogeneity of the hyperintense mass with improved visualization of the serpiginous or serpentine pattern with enhancement, which is characteristic of soft tissue hemangiomas.

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Figure 6. Retained contrast and persistence of enhancement is noted on 15 minute delayed post contrast fat suppressed images.

Diagnosis: Arteriovenous hemangioma involving intramuscular plane of second web space with dorso-plantar extension.

Discussion: Soft tissue hemangiomas are one of the most common tumors of childhood and comprise 10 percent of all benign vascular tumors. They are composed of vascular elements embedded in fibrofatty tissue and can arise from cutaneous, intermuscular, synovial, subcutaneous, intramuscular or mixed tissues. Clinical manifestations may include pain, the presence of a mass, soft tissue swelling, subcutaneous discolorations and, less frequently, neurologic symptoms secondary to impingement of a nerve bundle. These symptoms may be present for years before a diagnosis is made.

MR imaging is the recommended follow-up study to further characterize a soft tissue mass. T1-weighted imaging usually shows a heterogeneous mass of intermediate signal with lacy-appearing interspersed high signal areas representing interspersed fat; fatty overgrowth is characteristic of soft tissue hemangiomas. T2-weighted imaging shows a predominantly high signal intensity, heterogeneous mass. Interspersed areas of signal void can occur on both T1- and T2-weighted imaging and may represent relatively high velocity blood flow, whereas rounded foci of low signal are due to thrombi, phleboliths, or dense fibrous tissue. Contrast-enhanced images may demonstrate enhancement in a serpiginous manner. Ultrasound is less helpful because of the low specificity of the hyperechogenic mass commonly found.

The definitive diagnosis is determined by biopsy. Treatment depends on the location, size and subtype of the soft tissue hemangioma. Superficial capillary hemangiomas are often treated conservatively as their natural history is involution with time. For deep-seated soft tissue hemangiomas, however, wide local excision is the optimal management in order to prevent recurrence.

References
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