British Journal of Radiology (2003) 76, 753-754
© 2003 British Institute of Radiology
doi: 10.1259/bjr/56644744
An incidental finding
H Roach, FRCR,
P Chowdhury, MRCP and
H Adams, FRCR
Department of Radiology, Llandough Hospital, Penlan Road, Penarth, South Glamorgan CF64 2XX, UK
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Introduction
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A 33-year-old man with a known history of Crohn's disease presented during an exacerbation. He reported no respiratory symptoms.
A posteroanterior chest radiograph was performed, however, and found to be abnormal (Figure 1
). A CT of the thorax was therefore carried out (Figure 2).
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Figure 2. (a) Axial CT image of the thorax scanned in the arterial phase following intravenous contrast medium administration (viewed on soft tissue windows). (b) Axial CT image of the thorax viewed on bone window settings.
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What are the abnormalities shown and what is the diagnosis?
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Answer
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The chest radiograph demonstrates a large left-sided anterior mediastinal mass obscuring the left heart border. CT confirms the presence of an anterior mediastinal mass containing several flecks of calcification. When the images are viewed on bone windows some of the calcification is seen to be ring-like, characteristic of phleboliths. Delayed images also demonstrated a large draining vein (Figure 3). The imaging features are all consistent with the diagnosis of anterior mediastinal haemangioma, which was confirmed via open surgical biopsy.
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Figure 3. Delayed post contrast axial CT image viewed on soft tissue settings demonstrating a large draining vein (arrows).
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Benign mediastinal haemangiomas are rare tumours, accounting for no more than 0.5% of mediastinal masses [1, 2]. They are classified according to the size of their vascular space into capillary, cavernous or venous haemangiomas [1]. Over 90% are capillary or cavernous [1]. Most are found in the anterior mediastinum [3] with fewer occurring in the posterior mediastinum.
There is no recognised sex predeliction and patients under 35 years old are most commonly affected [2, 4]. As with this patient, up to half of patients are asymptomatic, with most of the remainder presenting with non-specific symptoms such as cough, chest pain and dyspnoea [2]. Multifocal associated lesions in the mediastinum, skin, spleen, liver and kidneys have been recognised [4] and they may be associated with hereditary haemorrhagic telangiectasia [2].
Plain radiograph appearances are usually of a round or lobulated mass with smooth margins. Calcified phleboliths are thought to be reasonably specific [5] and are seen in up to 10% on chest radiography [1, 5]. CT probably shows them more frequently [5]. Non-specific punctate calcification is seen more often [2] and may appear similar to that seen in teratomas or cartilaginous lesions [2].
Mediastinal haemangiomas can appear homogeneous or heterogeneous on unenhanced CT [1, 2]. Following intravenous contrast medium administration, enhancement is heterogeneous [2, 3], but enhancement is often poor [1]. There may be central enhancement in vascular channels or less commonly peripheral enhancement. Homogeneous enhancement is very uncommon [2].
Most haemangiomas are well marginated on CT. They do not, however, usually have a true capsule. This, along with the lack of other compressive structures in the mediastinum, could explain the significant haemorrhagic risks of core needle biopsy [6].
Histological diagnosis is required to distinguish these lesions from malignant vascular tumours [6]. Surgery, rather than percutaneous biopsy, is recommended for diagnosis and treatment, but there is still potential for substantial blood loss. An infiltrative appearance on CT correlates well with invasive behaviour and unresectability [2]. CT can also demonstrate aberrant draining vessels (Figure 3
), which is vital for surgical planning [6].
Reports of MR appearances are rare, but a relative hypointensity with signal characteristics similar to skeletal muscle on T1 weighted images and hyperintensity on T2 weighted images have been reported [5].
In summary, the presence of soft tissue phleboliths is an important finding in mediastinal haemangioma. Recognition of this feature will direct the patient towards open surgical biopsy or resection, and should avoid potentially hazardous percutaneous image guided biopsy. Delayed images should also be performed to delineate any draining veins.
Received for publication November 6, 2002.
Accepted for publication December 16, 2002.
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References
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- Abe K, Akata S, Ohkubo Y, Park J, et al. Venous haemangioma of the mediastinum. Eur Radiol 2001;11:73–5.[CrossRef][Medline]
- McAdams HP, Rosado-de-Christenson ML, Moran CA. Mediastinal hemangioma: radiographic and CT features in 14 patients. Radiology 1994;193:399–402.[Abstract/Free Full Text]
- Klecker RJ, Sinclair DS, King MA. Case 1. Mediastinal hemangioma. AJR Am J Roentgenol 2000;175:866.[Free Full Text]
- Moran CA, Suster S. Mediastinal hemangiomas: a study of 18 cases with emphasis on the spectrum of morphological features. Hum Pathol 1995;26:416–21.[CrossRef][Medline]
- Seline TH, Gross BH, Francis IR. CT and MR imaging of mediastinal hemangiomas. J Comput Assist Tomogr 1990;14:766–8.[Medline]
- Cheung YC, Ng SH, Wan YL, Tan CF, Wong HF, Ng KK. Dynamic features of mediastinal hemangioma: more information for evaluation. Clin Imaging 2000;24:276–8.[CrossRef][Medline]
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