British Journal of Radiology (2007) 80, e145-e146
© 2007 British Institute of Radiology
doi: 10.1259/bjr/49643955
Nasopharyngeal liposarcoma MRI imaging features and a review of the literature
S Chakraborty, MBBS, MRCP, DMRD
E E Kassel, MD, DDS, FRCPC
and
E Yu, MD, FRCPC
Princess Margaret Hospital, University Health Network, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9
Correspondence: Dr Eugene Yu, Medical Imaging, University of Toronto, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9, Canada. E-mail: eugene.yu{at}uhn.on.ca
 |
Abstract
|
|---|
We present a case of liposarcoma in a 37-year-old female with a chronic history of nasal stuffiness. MR imaging revealed a fatty lesion in the nasopharynx. Subsequent tissue sampling and histopathology demonstrated features consistent with a liposarcoma.
|
Introduction
|
|---|
Liposarcoma is a common soft tissue malignancy that occurs infrequently in the head and neck. Liposarcoma of the nasopharynx is exceptionally rare, with only two cases having been described in the English literature [1, 2]. We present a case of nasopharyngeal liposarcoma which was treated with radiotherapy.
|
Case report
|
|---|
A 37-year-old female presented with a 9 month history of nasal stuffiness and a sensation of 'blockage and popping' in the right ear. There was no history of epistaxis and she denied any headache or facial paresthesia. Endoscopic evaluation showed a 1 cm right-sided nasopharyngeal mass situated at the posterior aspect of her inferior turbinate just anterior to the eustachian tube orifice.
MRI showed a right-sided mass (Figure 1a
) measuring approximately 1.8x1.2x1.8 cm along the right lateral wall of the nasopharynx posteriorly. The lesion showed heterogeneous and predominantly high signal intensity on T1 weighted imaging (Figure 1a,b) and low signal intensity on the fat-saturated T2 weighted sequences (Figure 1d,e). The T1 weighted images showed faint internal striations. Enhancement was noted following contrast administration (Figure 1c). There was no evidence of adenopathy. Differential diagnosis included lipoma and liposarcoma.
View larger version (138K):
[in this window]
[in a new window]
|
Figure 1. (a–f) MR images show right-sided nasopharyngeal mass. (a) Axial T1 weighted image shows a high signal mass (arrowhead) in right nasopharynx. (b) Coronal T1 weighted image shows thick septations within this high signal mass. (c) Post-gadolinium T1 weighted image shows enhancement of the mass. (d) Axial T2 weighted fat-saturated image shows the lesion to be of low signal and is similar to the signal in the subcutaneous fat. (e) Coronal T2 weighted fat-saturated image shows saturation of signal as compared to (b). (f) Follow-up post-radiotherapy image shows no significant change in size or signal characteristics of the lesion.
|
|
Endoscopic debulking and biopsy of the mass was performed. Histopathological examination revealed a Grade 1 sclerosing liposarcoma. Definitive therapy involving surgical resection and radiotherapy was recommended but the patient declined surgery and opted to proceed with radical radiotherapy.
Following 70 Gy (56 Gy in 28 fractions, followed by 24 Gy as stereotactic radiotherapy using IMRT) of radiation therapy, follow-up MR imaging (Figure 1f
) did not reveal any significant change in the lesion. A repeat biopsy confirmed residual tumour. Surgical resection of the residual tumour was again suggested but the patient again declined.
|
Discussion
|
|---|
Liposarcoma is a tumour derived from primitive cells that undergo adipose differentiation. The American Cancer Society's "Key Statistics About Sarcoma" states that it is the second most common soft tissue sarcoma and accounts for 15% of all soft tissue sarcomatous tumours in the body. It typically occurs in the deep soft tissues of the extremities and in the retroperitoneum. Only 1.8–6.2% occur in the head and neck region [3], mostly affecting the neck (28%), larynx (20%) and hypopharynx (18%) [4]. It is largely a disease of adults, with the highest incidence in patients between the ages of 40 and 60 years. There is a slight male predominance. Cases of head and neck liposarcoma have been shown to arise in a slightly younger patient population, with a peak incidence around 40 years of age [3]. There is no known association with ethnicity or geography. Liposarcomas usually develop de novo rather than due to sarcomatous change in a pre-existing lipoma. The current classification system accepted by the World Health Organization for liposarcomas consists of five subtypes: (1) well differentiated (which includes the adipocytic, sclerosing, and inflammatory subtypes), (2) myxoid subtype, (3) dedifferentiated subtype (containing non-lipogenic sarcoma), (4) round-cell subtype and (5) pleomorphic subtype. The latter three subtypes are considered to represent the poorly differentiated high-grade liposarcomas.
On histology, the characteristic cell is the lipoblast. These cells have a characteristic hyperchromatic "chicken claw" shaped nucleus that is indented by cytoplasmic fat globules. While the lipoblast is frequently observed, its presence is not absolutely required for the tissue diagnosis, which does require the presence of atypical stromal cells. Myxoid liposarcomas are composed of three main tissue components: proliferating lipoblasts, a delicate plexiform capillary pattern and a myxoid matrix [5]. Pleomorphic liposarcomas show an extreme degree of cellular pleomorphism, including bizarre giant cells and it may be difficult to differentiate these tumours from malignant fibrous histiocytoma in the absence of characteristic lipoblasts. The pleomorphic, dedifferentiated and round-cell subtypes are the most aggressive types of liposarcoma. These three subtypes have a higher rate of metastases and frequently show haemorrhage and cystic necrosis.
The imaging characteristics vary considerably, depending on both macroscopic features and the tumour subtype. The well-differentiated type can appear identical to a benign lipoma and appear as a well-defined, lobulated fatty mass with thin septations. MR imaging shows a high signal intensity lesion on T1 weighted sequences and intermediate signal on T2 weighted sequences with signal attenuation following fat-saturation. The high-grade subtypes may show a less well-defined margin, the presence of thicker septa [6], a more heterogeneous internal architecture as well as the presence of non-adipose tissue. They may also show moderate or marked enhancement. The tumour grade is seen to increase with the degree of tumour haeterogeneity and contrast enhancement [5]. The aggressive subtypes may show areas of necrosis and haemorrhage. In this case, the presence of internal haeterogeneity and a striated appearance should be suggestive that this was not a simple lipoma and a more aggressive lesion was possible.
The management of liposarcomas in the head and neck has been based largely on experience with those tumours affecting the extremities and retroperitoneum. Wide surgical excision alone is considered appropriate for most low-grade liposarcomas. However, because it may be difficult or impossible to achieve complete excision of deep-seated low-grade liposarcoma, adjuvant radiotherapy/chemotherapy is employed in these cases in an attempt to reduce the risk of local recurrence.
The prognosis varies depending on the site of origin, the histological subtype, the tumour size, tumour necrosis and vascular invasion [7]. Liposarcomas occurring in deep anatomical sites such as the retroperitoneum and mediastinum tend to recur or metastasize at a far higher rate than those occurring in the limbs. This is almost certainly related to the late detection of these tumours, as well as the inability to obtain adequate surgical margins in many cases. Metastases are more common in high-grade subtypes. Oral cavity liposarcomas have a poorer prognosis compared with other locations in the head and neck [4]. Pharyngeal liposarcomas appear to have a more indolent course. The 5-year survival rate for a deep-seated and high-grade liposarcoma is less than 50%, whereas that of a well-differentiated subtype is almost 100% [4].
|
Conclusion
|
|---|
We describe a rare case of nasopharyngeal liposarcoma of the sclerosing subtype. This lesion was treated with a course of radical radiotherapy after the patient declined surgery.
Received for publication April 23, 2006.
Accepted for publication May 19, 2006.
|
References
|
|---|
- Nageris B, Feinmesser M, Brama I, Feinmesser R. Liposarcoma of the nasopharynx: a case report. Ear Nose Throat J 1991;70:520–2.[Medline]
- Knowles CH, Huggill PH. Liposarcoma: with report of a case in a child. J Pathol Bacteriol 1954;68:235–45.[Medline]
- Yueh B, Bassewitz HL, Eisele DW. Retropharyngeal liposarcoma. Am J Otolaryngol 1995;16:331–40.[CrossRef][Medline]
- Golledge J, Fisher C, Rhys-Evans PH. Head and neck liposarcoma. Cancer 1995;76:1051–8.[CrossRef][Medline]
- Arkun R, Memis A, Akalin T, Ustun EE, Sabah D, Kandiloglu G. Liposarcoma of soft tissue: MRI findings with pathologic correlation. Skeletal Radiol 1997;26:167–72.[CrossRef][Medline]
- Kransdorf MJ, Bancroft LW, Peterson JJ, Murphey MD, Foster WC, Temple HT. Imaging of fatty tumors: distinction of lipoma and well-differentiated liposarcoma. Radiology 2002;224:99–104.[Abstract/Free Full Text]
- Gustafson P, Rydholm A, Willen H, Baldetorp B, Ferno M, Akerman M. Liposarcoma: a population-based epidemiologic and prognostic study of features of 43 patients, including tumor DNA content. Int J Cancer 1993;55:541–6.[Medline]
Top
Abstract
Introduction
