British Journal of Radiology (2004) 77, 68-70
© 2004 British Institute of Radiology
doi: 10.1259/bjr/11673389
Progressively enlarging paracardial lipoma in a child
A Trusen, MD
1
M Beissert, MD, PhD
1
G Schultz, MD
1
K Ergezinger, MD
2
A Marx, MD, PhD
3 and
K Darge, MD, PhD
1
1 Department of Paediatric Radiology, Institute of Radiodiagnostics, 2 University of Children's Hospital and 3 Institute of Pathology, University of Wuerzburg, Josef-Schneider-Straße 2, 97080 Wuerzburg, Germany
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Abstract
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Mediastinal lipomas are slowly growing tumours. Only very few cases have been reported in children. None of these included a rapidly enlarging lipoma. We present an 8-year-old severely adipose girl with an incidentally diagnosed mediastinal lipoma that showed rapid enlargement within 7 weeks.
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Introduction
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The list of differential diagnoses of a rapidly enlarging pericardial mass is very extensive and comprises among others pericardial cysts and tumours such as lymphoma or thymoma [1–3]. Additionally, the differential diagnosis of fat containing mediastinal masses include lipomas, mediastinal lipomatosis, omental fat herniation and mature teratomas. Liposarcomas and lipoblastomas must also be considered, even though they are very rare in children and have only been reported in few cases [4, 5]. Lipoblastomas are typically found in children below the age of 3 years [6–8].
To our knowledge, a fast growing mediastinal lipoma in a child has not previously been reported. The most common site for a mediastinal lipoma is the anterior inferior mediastinum [3]. Mediastinal lipomas have been divided into three groups according to their location and form: 1. Tumours confined within the thoracic cage; 2. Intrathoracic lipomas that extend upwards into the neck; and 3. Intrathoracic lipomas with an extrathoracic extension forming a dumbbell configuration [9]. We present a case of a very adipose 8-year-old girl with a rapidly growing intrathoracic lipoma in the anterior mediastinum.
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Case report
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A triangular mass in the cardiophrenic angle was found incidentally in an adipose 8-year-old girl when a chest radiograph was performed to rule out pulmonary infection (Figure 1a
). She was admitted to our hospital for further investigations of the mass. On admission the patient had cough, fever and vomiting. The body weight of 53.5 kg was considerably above the 97th percentile, while her height of 137 cm was on the 75th percentile.
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Figure 1. (a) Chest radiograph performed to rule out pulmonary infection shows incidentally a triangular shadow in the cardiophrenic angle on the right side [Date of examination 20.11.00]. (b) Follow-up chest radiograph performed 7 weeks later due to recurrent airway infection demonstrates an enlargement of the mass even allowing for a slightly different inspiration [Date of examination 12.1.01].
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B-mode ultrasound (Sonoline Elegra®, Siemens, Issaquah, USA) demonstrated a 4 x 5 cm (transverse plane) solid mass in the anterior compartment of the mediastinum in the right pericardial angle with a moderately low echogenicity (Figure 2a). Colour Doppler was not very informative due to cardiac motion-artefacts, but hyperperfusion of the mass was not detected.
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Figure 2. (a) Ultrasound shows a solid mass in the transverse plane with 4.4 x 5.0 cm2 [Date of examination 20.12.00]. (b) Follow-up ultrasound 5 weeks later demonstrates an enlargement of the mass in the transverse plane (5.9 x 5.7 cm2) [Date of examination 29.1.01].
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An MRI examination (1.5 T Siemens Symphony®, Erlangen, Germany) of the thorax was carried out using the following examination protocol: pre-contrast and post-contrast enhanced T1 (0.1 mmol Gd-DTPA/kg body weight) and T2 weighted turbo spin echo (TSE)-sequences in transverse and frontal planes. An additional sequence with fat suppression complemented the protocol. The mass with a volume of 43 ml in the right cardiophrenic angle, had signal intensities equivalent to fat, hyperintense in T1 weighted and T2 weighted images (Figure 3a) as well as decreased signal intensities with fat suppression. Contrast enhancement was not observed. No infiltration of the mass into adjacent tissues such as chest wall, heart and diaphragm was seen. Since no signs of malignancy were present, a conservative approach was taken.
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Figure 3. (a) MRI of the chest, T1 weighted turbo spin echo (TSE) sequence, repetition time (TR) 600 ms, echo time (TE) 32 ms, in transverse plane shows a fatty mass in the right cardiophrenic angle consistent with a lipoma [Date of examination 21.12.00]. (b) The follow-up MRI of the chest was performed due to the rapid enlargement of the mass. T1 weighted TSE-sequence, TR 600 ms, TE 32 ms, in the same plane as in the first examination. A significant enlargement of the fatty mass was noted without signs of malignancy. At the same time the thickness of the subcutaneous tissue had increased [Date of examination 30.1.01].
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Recurrent pulmonary infection prompted a second chest radiograph outside our clinic 7 weeks later. This chest radiograph (Figure 1b
) revealed enlargement of the mass compared with the first chest film (Figure 1a). The patient was subsequently referred to our hospital for further evaluation. B-mode ultrasound confirmed that the lesion had increased in size. It measured 6 x 6 cm in the transverse plane (Figure 2b). Due to the expansion of the mass, a follow-up MRI was initiated. Scanning parameters were the same as in the previous examination. Again the typical features of a benign lipoma with no signs of malignancy were detected (Figure 3b). The enlargement of the mass was confirmed, the volume in this examination was found to be 90 ml. In the axial plane it was observed to extend adjacent to the anterior chest wall. An additional finding on the MRI was the marked increase in the thickness of the subcutaneous tissue of the chest and the upper abdomen. No clinical signs were present and the physical examination was unremarkable except for the severe adiposity. Between the first and second admission there was an increase of 3 kg body weight. A decision to undertake thoracotomy and excision of the mass was made because of the rapid growth, despite the benign findings on MRI.
The mass was completely excised without any complication. Intraoperatively the paracardiac location of the lesion was confirmed. Histological examination confirmed the diagnosis of a benign lipoma (Figure 4). No evidence for malignancy was found histologically. The patient was discharged 4 days after the operation in good clinical condition. A year after surgery the girl is free of symptoms and the tumour has not recurred.
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Figure 4. Representative histology of the paracardial lipoma located underneath the mediastinal pleura (arrow). Absence of lipoblasts and mitoses. (H&E; x 100).
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Discussion
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Among paracardial or pericardial masses pericardial cysts are frequent. In our case ultrasound ruled out a cyst. On MRI a fatty tumour was diagnosed. Among fat containing masses, pericardial fat pads as well as lipomas can be found in children. The borders of the lesion were sharp and no signs of malignancy were present, supporting the diagnosis of a mediastinal lipoma. Lipomas are benign fatty tumours with slow growth rate. Lipomas of the retroperitoneum and the mediastinum may show malignant degeneration. So far only a few mediastinal lipomas in children have been reported, all of which were completely confined to the thorax [9]. As in our case, most of the lipomas are detected incidentally on chest films, or during autopsies. Symptoms arise through compression of lung tissue or by altering ventricular function. Upper respiratory infections, chest pain and dyspnoea have been described in patients with lipomas. In our patient recurrent pulmonary infections occurred, but no other clinical symptoms were evident. Among thoracic lipomas thymolipomas are a histological subgroup. Rosado-de-Christenson et al found in their analysis of 27 mediastinal thymolipomas in 22 cases the common location to be in the anterior inferior mediastinum [3]. In 12 patients, the masses draped along the ipsilateral diaphragm, as was seen in our patient. Contrary to our patient they found varying thymic tissue within the lesions.
Our adipose patient had gained weight, at the same time the lipoma increased in size. No underlying disease was found. The rapid growth of the tumour within 7 weeks may have been due to the general weight increase of the patient in terms of an increase in size of the fat cells or to an increase in their number. This unique clinical course demonstrates that a mediastinal lipoma in a child can show rapid size increase and still be benign. Unfortunately, this single case cannot serve to make a general recommendation to refrain from surgical intervention in cases of progressively enlarging mediastinal lipoma.
Received for publication August 23, 2002.
Revision received March 3, 2003.
Accepted for publication April 24, 2003.
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References
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- Chiyo M, Fujisawa T, Yasukawa T, Shiba M, Shibuya K, Sekine Y, et al. Successful resection of a primary liposarcoma in the anterior mediastinum in a child: report of a case. Surg Today 2001;31:230–2.[CrossRef][Medline]
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- Kendig EL, editor. Kendig's disorders of the respiratory tract in children. Philadelphia, PA: W.B. Saunders company, 1998;780.
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Abstract
Introduction
