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Soft tissue haemangiomas are common benign vascular lesions that can be accompanied by reactive changes in the adjacent bone structure. This study aimed to discuss the MRI features of soft-tissue haemangiomas with an emphasis on changes in bone.
The radiographic and MRI findings of 23 patients (9 males, 14 females; mean age 25 years; age range 2–46 years) with soft-tissue haemangiomas were analysed retrospectively. MR images were evaluated for location of the lesion, size, configuration, signal features, contrast patterns, proximity to adjacent bone and changes in the accompanying bone. Excisional biopsy was performed in 15 patients.
Radiographs demonstrated phleboliths in 8 patients (34%) and reactive bone changes in 4 (19%). On MRI, T1 weighted images showed that most of the lesions were isointense or isohyperintense, as compared with muscle tissue; however, on T2 weighted images all lesions appeared as hyperintense. Following intravenous gadolinium-diethylene triamine pentaacetic acid (DTPA) administration, homogeneous enhancement was observed in 3 lesions and heterogeneous enhancement was seen in 19. No enhancement was observed in one patient. Bone atrophy adjacent to the lesion was observed in four patients.
MRI is the most valuable means of diagnosing deep soft-tissue haemangiomas. Bone changes can accompany deeply situated haemangiomas; in four of our patients, we found atrophy of the bone adjacent to the lesion. To our knowledge, this is the first report in the literature regarding atrophy of the bone adjacent to a lesion.
Soft-tissue haemangioma, a frequently encountered benign vascular lesion, accounts for 7% of all benign soft-tissue tumours [1-5]. Such lesions can be cutaneous, subcutaneous, intramuscular or synovial . Intramuscular haemangioma is rare and responsible for 0.8–1.8% of all haemangiomas [3,5,6]. Superficial haemangiomas are diagnosed easily because they cause discolorations of the skin; imaging techniques are rarely needed . However, deep lesions are difficult to diagnose clinically, because they do not cause discolorations and grow slowly; imaging techniques are required to discriminate these deep haemangiomas from malignant lesions [1,2,7]. Bone changes accompanying haemangioma have been reported previously in the literature and include cortical thickening, erosion, medullary sclerosis, trabecular coarsening and hypertrophy [1,8]. Here, we present the MRI manifestations of soft-tissue haemangiomas and reactive changes to the neighbouring bones. To the best of our knowledge, this is the first report of its kind in the English literature.
This was a retrospective study of 23 patients (9 males, 14 females; mean age 25 years; age range 2–46 years) who presented at our hospital between May 2001 and April 2006 with pain and/or swelling at the site of lesions; on the basis of MRI and plain radiographs, these patients were thought to have soft-tissue haemangiomas. Two radiologists (AP, MAP) retrospectively reviewed both the radiographs and the MR images and arrived at a consensus regarding the interpretation of the imaging features. Although all patients had plain radiograph and MRI results, only four had angiography. Table 1 shows the distribution of patients by age, complaint, duration of complaint, type and size of lesion and the lesion's location based on the compartment anatomy and presence of phleboliths.
MRI was performed using an MR unit with a 1.5 T superconductive magnet and a body phased-array coil (Magnetom Vision, Siemens, Erlangen, Germany). Routine MRI involved T1 weighted spin echo (SE) (repetition time (TR) 550–750 ms; echo time (TE) 12–20 ms; number of excitations (NEX) 1–2; section thickness 3–4 mm; gap 1 mm), T2 weighted SE (TR 3500–4000 ms; TE 80–99 ms; NEX 1–2; section thickness 3–4 mm; gap 1 mm) and fat-suppressed T2 weighted turbo spin echo (TSE) (TR 4000–4500 ms; TE 90–99 ms; section thickness 3–4 mm; gap 1 mm) images in at least one plane. Following intravenous injection of 0.1 mmol kg–1 paramagnetic contrast medium, T1 weighted SE or fat-suppressed T1 weighted SE (TR 800–980 ms; TE 15–25 ms; NEX 1–2; section thickness 3–4 mm; gap 1 mm) images in at least two planes were obtained from all patients. The field of view (FOV) was adjusted for the location of the lesions. All MRI sequences had an image matrix of 192×256. Pathological biopsy results were available for 15 patients.
Table 2 shows the MRI signal properties, contrast patterns and bone changes of the lesions together with their distance to the neighbouring bones.
Plain radiographs showed phleboliths in 8 patients (34%; Figure 1). All lesions with phleboliths were located intramuscularly. On MRI, phleboliths were visualised in the form of nodular hypointense spots. The size of the focal lesions ranged from 1×1×2 cm to 6×11×14 cm. The lesions diffusely involved the extremities in four patients (Figure 2). Five patients (three of whom were children) had a lesion with a subcutaneous component; two of the children had both haemangioma and lymphangioma.
On T1 weighted MR images, the lesions and neighbouring muscle tissue were isohyperintense in 13 patients, isointense in 7 patients, slightly hyperintense in 2 patients and hypointense in 1 patient (Figure 3). A hyperintense rim in the margin of the lesion was observed in three patients (Figure 3d).
On T2 weighted MR images, all lesions had hyperintense signals. On T2 weighted MR images, there were nodular hypointense areas in the lesions in 13 patients (Figure 4). There was lobulation and septation in 19 patients and septation alone in one patient. Two patients had a fluid–fluid level in the haemangioma (Figure 5). There was a neighbouring lesion with a haemosiderin ring in its membrane in one patient, suggestive of a haematoma in its chronic stage. The vessel supplying the lesion could be viewed in one patient.
Following injection of the contrast medium, 19 patients had heterogeneous enhancement patterns, while 3 patients had homogeneous enhancement patterns (Figure 6). One patient did not show contrast enhancement.
The lesion was in contact with the neighbouring bone cortex in 14 patients, 4 of whom had atrophy of the bone adjacent to the lesion. Of these four patients, one had a lesion extending from the elbow to the middle segment of the forearm involving both volar and dorsal compartments. Plain radiographs showed diffuse atrophy in one-third of the proximal radius, cortical thickening and trabecular coarsening in the ulna and soft tissue phleboliths. Another patient had an intramuscular lesion in the thigh with a subcutaneous component. The lesion was located in the anterior, medial and posterior compartments and the femur adjacent to the lesion had atrophy (Figure 7). Another patient had diffuse intramuscular lesions located in both the thigh and the lower leg. The lesions involved the anterior and posterior compartments. Both MRI and plain radiographs showed diffuse atrophy in the femur (Figure 8). The final patient had lesions unilaterally involving the entire lower extremity. The cutaneous, subcutaneous and intramuscular lesions involved all anatomical compartments of both the thigh and the lower leg. There was atrophy in the femur, expansion and sclerosis of the medullary bone distal to the fibula, a periosteal reaction of the lateral cortex of the tibia, thickening of the medial cortex of the tibia and sclerosis of the medullary bone (Figure 9). On MRI, none of the four patients had signal changes from the medullary bone. In the remaining 10 patients with lesions that were in contact with the bone, there were no reactive bone changes.
The diagnosis of soft-tissue haemangioma was based on excisional biopsy in 15 patients (65%) and on clinical signs and MRI findings in 8. Histological examination in 15 patients revealed that the tumour was cavernous haemangioma in 13 cases and arteriovenous haemangioma in 2. Of the four patients who underwent angiography, one had pre-operative embolisation and three had sclerotherapy. On pathological examination, two patients received a diagnosis of synovial haemangioma (Figure 10). Two children had haemangioma accompanied by lymphangioma. One child had had abdominal lymphangioma 1 year earlier. One patient with a lesion in the knee had a recurrence 3 years after surgery.
There is no general agreement regarding the aetiology of soft-tissue haemangioma. Although symptoms frequently appear after a trauma, most of these tumours are thought to be congenital [1,5,9]. Patients with haemangioma deeply located in tissue present with pain, swelling or both. Sometimes, patients note that the lesions grow and then get smaller .
The lesions are located in the lower extremities in 45% of patients . Patients with phleboliths (20–67%) have typical soft-tissue haemangioma [1,4]. Malignant transformation is rare [1,10]. Metastases of the lesions have not been reported . No sex preponderance was stated in the study by Wild et al , although the lesions appeared more frequently in women  as reported in the present study. In 90% of patients, lesions are diagnosed in the first three decades of life . In line with this observation, in 65% of our patients the lesions occurred in the first three decades of life.
Histologically, soft-tissue haemangioma can be classified into five types: capillary, cavernous, arteriovenous, venous and mixed haemangioma [1,3,4]. Capillary haemangioma is the most frequent haemangioma. This type of lesion is located in the cutaneous or subcutaneous tissues and is diagnosed in the first decade of life. Most instances of capillary haemangioma undergo involution spontaneously. Cavernous haemangiomas are large, deeply located and are diagnosed later in life; these lesions are frequently intramuscular, do not have spontaneous involution and require surgical treatment . Arteriovenous haemangioma is composed of shunts and prevalence rates vary ; these lesions can be superficial or deeply located . Venous haemangiomas are made up of clusters of large venous vessels with thick walls . These lesions are typically located deep in the retroperitoneum, mesentery and the extremities . Mixed haemangioma is, microscopically, a mixture of capillary and cavernous haemangioma [4,11].
Superficial haemangiomas are diagnosed easily because they cause discolorations of the skin and rarely require imaging techniques . However, lesions deep in the tissues are not diagnosed easily because they grow slowly and do not cause discolorations of the skin. Imaging techniques are necessary to differentiate such haemangiomas from malignant lesions [1,2,7].
MRI is the standard imaging technique for diagnosing soft-tissue haemangioma . On T1 weighted images, compared with muscle tissue, intensities of the lesions are isointense or hyperintense with unclear margins [6,7,11-13]. In the present study, in keeping with the literature, T1 weighted images showed haemangiomas to be isointense or hyperintense in 20 patients; however, in contrast with the literature, we found that two lesions were diffuse hyperintense and one was hypointense on T1 weighted images. On T2 weighted images, haemangiomas are typically hyperintense and have clear margins and lobulated contours. Although these signs are characteristic of haemangiomas, they are not pathognomonic . As previously reported, the present study demonstrates hyperintensity on T2 weighted images in all cases. In addition, all lesions had clear margins and most possessed lobulated contours. Marked hyperintensity of the lesions on T2 weighted images is due to increased fluid content secondary to stagnant blood flow in large vessels [12,13]. Ehara et al  reported five cases with a fluid–fluid level in haemangioma. In the present study, two patients with intramuscular haemangioma located in the forearm had a fluid–fluid level.
Thin, linear, hypointense structures inside the lesions on T2 weighted images result from fibrous septa between the vessels . Moreover, occasional punctuate or reticular hypointense areas might be due to fibrous tissue, fast blood flow in vessels, calcification, ossification, haemosiderin, smooth muscle components or a thrombosis in vascular structures [2,11,13]. In such cases, plain radiographs and CT can be useful in differentiating calcification from ossification. In this study, 13 patients (56%) had nodular hypointense areas on T2 weighted MRI images. Only eight of these patients had phleboliths on plain radiographs, a finding that led us to believe that not all nodular hypointensities on T2 weighted images corresponded to phleboliths.
Intramuscular haemangiomas contain various amounts of fat, smooth muscle, myxoid stroma, thrombi and haemosiderin [11,12]. In some cases, haemangiomas contain so much fat that they can be mistaken for lipomas . Lesions larger than 2 cm typically have different kinds of tissues and, therefore, have heterogeneous signals .
Deeply located, large haemangiomas sometimes cause changes in the neighbouring bone [1,3,8,10]. Ly et al  divided bone changes into three categories: periosteal, cortical and medullary. These authors classified the cortical changes into erosion, thickening, tunnelling and osteopenia; medullary changes were classified into osteosclerosis and trabecular coarsening. A correlation was indicated between bone changes and the distance between the lesion and the bone. Moreover, the authors reported medullary changes to be correlated not only with the proximity of the lesion to the bone, but also with the lesion's size . Sung et al  classified bone changes into periosteal reaction, osteopenia, bone enlargement, cortical erosion, trabecular coarsening and a combination of all these. Some authors emphasise an enlargement in the neighbouring bone in cases of diffuse haemangiomas [8,15]. In the present study, four patients had atrophy in the neighbouring bone. The precise mechanism of reactive bone changes in soft-tissue haemangioma remains unknown. Several factors could contribute to the development of such bone changes, including an extrinsic pressure effect of the lesion, dilated vessels and hyperaemia secondary to vascularity of the tumour . In our opinion, the mechanism for the development of bone atrophy might be related to the size, formation and duration of development of the mass prior to completion of bone growth. We believe that hypervascularity in the large and deeply seated soft-tissue haemangiomas might have caused disturbance of bone nutrition. In this study, in three of the four cases of bone atrophy, insufficiency of bone vascularisation could have resulted from the fact that the lesion was present in both subcutaneous and intramuscular compartments. Histopathological studies were undertaken of three of the four cases of bone atrophy; all three revealed cavernous haemangioma.
To our knowledge, in the English literature, there have been no reports of soft-tissue haemangioma associated with bone atrophy.
Although some researchers have noted that small haemangiomas rarely cause a periosteal reaction [7,10], Goto et al  claim this is not rare. These authors also proposed that a periosteal reaction could result from passive hyperaemia caused by a tumour, retraction or irritation of a tumour. Goto et al  claimed that a periosteal reaction was not stimulated by the size of the lesion, but that the distance between the lesion and the bone played an important role . De Filippo et al  hypothesised that the periosteal reaction results from increased local vascularity caused by the tumour. There have been conflicting comments on the relationship between bone changes and pain. Ly et al  found no relation between pain and bone changes, whereas Goto et al  reported that patients with haemangiomas associated with periosteal reaction more frequently had pain. None of the four patients with bone changes in our study complained of pain.
Deeply located haemangiomas are mostly intramuscular, but they can also be synovial . Intramuscular haemangiomas are frequently located in the trunk and lower extremities; these lesions rarely appear in the upper extremities . Synovial haemangiomas are rare and almost always involve the knee joint; patients with synovial haemangiomas complain about pain, swelling and effusion; these lesions most frequently appear in the suprapatellar region . Rare vascular tumours such as haemangioendothelioma and angiosarcoma, arteriovenous malformation, lymphangioma, lipoma, liposarcoma and other soft-tissue sarcomas might mimic haemangiomas [10,12,13].
Biopsy of soft-tissue haemangiomas can cause bleeding. In the present study, one patient with intramuscular haemangioma located in the forearm developed a spontaneous haematoma.
As for treating haemangiomas, symptomatic cases are treated with surgical resection or a laser [4,9,10]. Haemangioma has been reported to recur in 18% of patients who undergo surgery . Mixed haemangioma tends to recur most frequently, followed by capillary and cavernous haemangiomas. In our study, haemangioma recurred in one patient 3 years after surgery. When excision is not appropriate, radiotherapy or embolisation can be useful . We treated 15 patients with surgery, 3 with sclerotherapy under angiography and 1 with embolisation.
In conclusion, MRI is the most useful imaging technique for diagnosing soft-tissue haemangiomas and for determining tumour margins in that it provides multiplanar images and has excellent soft-tissue contrast enhancement. The presence of lobulation, septation and nodular hypointense foci on T2 weighted images makes the diagnosis easier. The presence of hypointense signals on T1 weighted images should not rule out haemangioma. In the present series, four patients with haemangioma had bone atrophy. This has not been reported previously in the literature. It should be kept in mind that soft-tissue haemangioma can be accompanied by bone atrophy as well as reactive bone changes, which has previously been reported.