British Journal of Radiology (2003) 76, 750-752
© 2003 British Institute of Radiology
doi: 10.1259/bjr/29206613
Metastatic liposarcoma of the thyroid gland
A R Azar, MD
1
B Weynand, MD
2
C Daumerie, MD
3 and
E Coche, MD
1
Departments of 1 Radiology, 2 Pathology and 3 Endocrinology, Cliniques Universitaires St-Luc, Université Catholique de Louvain, Avenue Hippocrate 10, 1200 Brussels, Belgium
Correspondence: Emmanuel Coche
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Abstract
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Metastatic liposarcoma of the thyroid gland is exceptionally rare. A case of pleomorphic liposarcoma, which manifested as a soft tissue lump in the neck, is described in a 30-year-old woman. Fine needle aspiration cytology permitted prompt diagnosis. The ultrasound and CT appearance of this type of thyroid metastasis is described which has not been previously reported in the literature.
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Introduction
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The majority of soft tissue sarcomas metastasize to the lungs. Liposarcomas may have a different metastatic pattern, with a tendency to disseminate towards extrapulmonary sites.
We report the case of a 30-year-old woman with a known history of liposarcoma of the right thigh, presenting with a painless nodule in the right side of her neck, which was confirmed to be in the right thyroid lobe on imaging. An ultrasound-guided fine needle aspiration cytology (FNAC) was consistent with a diagnosis of metastatic liposarcoma.
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Case report
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A 30-year-old woman consulted our institution, following the discovery of a recent swelling on the right side of her neck. 2.5 years previously she had presented with a liposarcoma of the right thigh, which had been treated by extensive surgical resection. The mass measured 120 x 90 x 50 mm. Histological examination revealed bizarre lipoblasts consistent with a high grade round cell liposarcoma. 10 months later, the patient re-presented with a local recurrence, treated by surgical resection and adjuvant radiotherapy (64.5 Gy). At consultation, physical examination demonstrated a painless large, soft tissue mass located in the right lower cervical area, mobile on swallowing. A neck ultrasound (Sequoia, Acuson, Mountain View, CA) was performed and revealed a large hypo-echoic nodule measuring 18 x 25 x 27 mm occupying the right lobe of the thyroid gland (Figure 1
). Ultrasound colour Doppler examination revealed a weak signal at the centre of the lesion. An ultrasound-guided fine needle aspiration of the nodule was performed using a 23 Gauge needle. Yellow viscous fluid was obtained and sent for cytological examination. On the thyroid FNAC, a few isolated atypical cells were observed in an haemorrhagic background. These atypical cells contained an irregular, hyperchromatic nucleus with a clearly visible nucleolus. Some cells were characterized by a huge intracytoplasmic vacuole, reminiscent of immature lipoblasts (Figure 2). A helical CT (MX Dual, Philips, The Netherlands) of the neck, chest and abdomen was then performed for staging. Neck CT was begun 35 s after intravenous contrast medium injection and confirmed the presence of a well defined, slightly heterogeneous mass occupying the right lobe of the thyroid gland. The density of the anterior part of the lesion was measured at 17 HU, and the periphery at –19 HU. Delayed CT of the neck was performed 3 min after contrast medium injection and showed heterogeneous enhancement of the thyroid nodule. The anterior component was more enhancing than the periphery with a density measured at 128 HU and 46 HU, respectively (Figures 3 and 4). Chest CT examination did not reveal any suspicious nodule in the lung parenchyma. A large pelvic mass measuring 190 x 160 x 130 mm was discovered on pelvic CT (Figure 5). This mass appeared heterogeneous and consistent with metastatic liposarcoma. The patient underwent an extensive resection of the pelvic mass whilst the thyroid mass was left in place. The abdominal gross specimen weighed 1530 g and measured 19 x 16 x 13 cm. The tumour mass was mostly delimited by a well-defined capsule. On section, the tumour showed an alternance of firm and myxoid tissue. A few necrotic areas were also described.
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Figure 1. Ultrasound of the neck. A large hypoechoic mass is visualized in the mid portion of the right thyroid lobe. The hyperechoic tip of the needle used for fine needle aspiration is seen at the periphery of the lesion (arrow).
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Figure 2. Left: surgical specimen of the thigh; right: thyroid fine needle aspiration cytology. The two specimens are composed of the same atypical cell population containing immature lipoblasts (vacuolated cells).
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Figure 3. Axial contrast-enhanced CT scan of neck. Early (35 s delay) reveals an heterogeneous hypodense lesion located on the right thyroid lobe.
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Figure 4. Delayed (3 min delay) axial contrast-enhanced CT scan of neck. Demonstrating significant enhancement of the right thyroid nodule is noted apart its medial and lateral margins.
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Figure 5. Axial contrast-enhanced CT of pelvis. Demonstrating a large heterogeneous mass discovered incidentally. This mass was resected and pathological examination was consistent with liposarcoma.
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On microscopic examination, the myxoid areas were mixed with very cellular ones. Both areas contained mature and immature lipoblasts with a high mitotic count, with the characteristic vascularization pattern of a liposarcoma.
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Discussion
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Liposarcomas were first described by Virchow in 1857 [1]. This tumour of mesenchymal origin is typically large and bulky and tends to have multiple satellite lesions extending beyond its boundaries. It is the second most frequent soft-tissue sarcoma in adults after malignant fibrous histiocytoma with an incidence of 20% [2]. It occurs almost exclusively in adults with a peak incidence between the 5th and 6th decades. It arises mainly in the trunk (42%) and the lower limbs (41%). Less frequently, it can develop in the upper limbs (11%) and in the head and neck region (1.8% to 6.3%) [3].
Liposarcomas are divided into histological subtypes with different microscopic appearances and slightly different behaviour. Stout [4] described four major histological variants of liposarcomas. Although some modifications do exist, this classification remains widely accepted. Liposarcomas can be divided into 1) well differentiated, 2) myxoid, 3) round cell, and 4) pleomorphic liposarcomas. Well differentiated tumours have the most favourable outcome with a 5 year survival rate estimated between 75% and 100%. Round cell and pleomorphic liposarcomas have the worst prognosis with 0 to 20% survival rate at 5 years.
The lung is known as the most common site of metastasis for soft tissue sarcomas. However, some authors [5, 6] have reported liposarcomas to have an unusual propensity for extrapulmonary sites for first metastasis, including the retroperitoneum; mediastinum; and bone. Some case reports even describe liposarcoma metastases in unusual locations such as the kidney, brain, omentum, scalp, ovary, liver, or heart. Bashir et al [7] recently reported for the first time a case of a pleomorphic liposarcoma metastatic to the thyroid gland. This metastatic nodule appeared as a cold area on 99Tcm pertechnetate scan but its radiological appearance was not described. Other cases of primary liposarcomas of the thyroid gland have been reported [8–10]. To the best of our knowledge, the ultrasound and CT appearance of metastatic liposarcoma of the thyroid gland have not been previously described. This lesion appeared hypoechoic on ultrasound and heterogeneous on CT. We found negative density values at the periphery of the lesion on unenhanced CT with a central enhancement on delayed enhanced CT (Figures 3 and 4
). It is difficult to say if negative attenuation values observed at the periphery of the lesion are due to the presence of fat or due to volume averaging of attenuation value measurements. We do not have correlation with gross and histological examination of this thyroid nodule to elucidate this peculiar CT appearance.
The radiology aspect of metastatic disease to the thyroid has been previously reported [11, 12]. Takashima et al [11] reviewed the imaging findings of 11 cases of pathologically verified metastatic tumours to the thyroid gland. These tumours typically had well defined margins and no calcification and sometimes had cystic portions. Metastatic disease to the thyroid can appear as hypoechoic or markedly hypoechoic areas without halo on ultrasound, as low density areas on CT, and as areas of varying signal intensities on MRI.
In our patient, FNAC provided a rapid and accurate diagnosis of the thyroid nodule and helped the clinician to turn his investigations towards a cervical, chest and abdominal spiral CT examination which enabled the discovery of a large pelvic mass. Surgical resection with a wide surgical margin is the treatment of choice in the case of localized liposarcomas.
In general, any new thyroid mass or swelling occurring in patients with a known malignancy, should be regarded as possibly metastatic until proven otherwise. FNAC under ultrasound guidance may be used to help diagnose a metastatic disease.
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Acknowledgments
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The authors thank Claire de Burbure for her assistance with manuscript preparation.
Received for publication April 16, 2002.
Revision received October 7, 2002.
Accepted for publication February 13, 2003.
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References
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- Virchow R. Einfall von bosartigen, zum theil in der form des neurons auftretenden fettgeschwullsten. Virchows Arch A Pathol Anat Histopathol 1857;11:281–8.
- Springfield D. Liposarcoma. Clin Orthop 1993;289:50–7.
- Yueh B, Bassewitz HL. Retropharyngeal liposarcoma. Am J Otolaryngol 1995;16:331–40.[CrossRef][Medline]
- Stout AP. Liposarcoma-the malignant tumor of lipoblasts. Ann Surg 1944;119:86–107.[CrossRef][Medline]
- Cheng EY, Springfield DS. Frequent incidence of extrapulmonary sites of initial metastasis in patients with liposarcoma. Cancer 1995;75:1120–7.[CrossRef][Medline]
- Vassilopoulos PP, Voros DN, Kelessis NG, Katsilieris JN, Apostolikas NG. Unusual spread of liposarcoma. Anticancer Res 2001;21:1419–21.[Medline]
- Bashir H, Nawaz MK, Shah MA, Ahmad E. Pleomorphic liposarcoma metastatic to the thyroid gland. Clin Nucl Med 2002;27:9–10.[CrossRef][Medline]
- Andrion A, Gaglio A. Liposarcoma of the thyroid gland. Fine-needle aspiration cytology, immunohistology, and ultrastructure. Am J Clin Pathol 1991;95:675–9.[Medline]
- Nielsen VT, Knudsen N, Holm IE. Liposarcoma of the thyroid gland. Tumori 1986;72:499–502.[Medline]
- Griem KL, Robb PK, Caldarelli DD, Templeton AC. Radiation-induced sarcoma of the thyroid. Arch Otolaryngol Head Neck Surg 1989;115:991–3.[Abstract/Free Full Text]
- Takashima S, Takayama F, Wang JC, Saito A, Kawakami S, Kobayashi S, et al. Radiologic assessment of metastases to the thyroid gland. J Comput Assist Tomogr 2000;24:539–45.[CrossRef][Medline]
- Ferrozzi F, Campodonico F, De Chiara F, Uccelli M, Saccani A. Thyroid metastases: the echographic and computed tomographic aspects. Radiol Med (Torino) 1997;94:214–9.
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Abstract
Introduction
