ClinicalRadiology(1992) 46, 253 256
Imaging of Alveolar Soft Part Sarcoma B. D. D A L Y , H. C H E U N G , P. A. GAINES*, M. J. B R A D L E Y t and C. M E T R E W E L I
Department of Diagnostic' Radiology and Organ Imaging, Chinese University, Prince of Wales Hospital, Hong Kong The imaging investigations in six patients with alveolar soft part sarcoma (ASPS) are reviewed. Five patients presented with a pelvic or lower limb mass and one with haemoptysis from pulmonary metastases. Magnetic resonance imaging (MRI), CT, Doppler US and angiography studies demonstrated the highly vascular nature of this rare tumour and the frequent occurrence of pulmonary and intracranial metastases. Previously unreported Doppler US and MR evidence of multiple enlarged vessels and high blood flow within primary and secondary ASPS tumours is emphasized. Imaging is of considerable importance both for pre-operative localization and long term surveillance of this slow growing but invariably disseminating tumour. Daly, B.D., Cheung, H., Gaines, P.A., Bradley, M.J. & Metreweli, C. (1992).
Clinical Radiology 46, 253-256. Imaging of Alveolar Soft Part Sarcoma Accepted for Publication 8 May 1992
Alveolar soft part sarcoma (ASPS) is a highly vascular malignant tumour which occurs most often in the soft tissues of the pelvis and lower limbs. It is rare, being one of the least frequently detected sarcomas and the pathological appearances were first recognized by Smetana and Scott in 1951 [1]. The cell of origin is as yet unknown and debated but the arrangement of cells on histopathological examination mimics that of the respiratory alveoli and hence the descriptive name [2,3]. ASPS is seen in all races, most frequently in young adults and usually presents clinically as a slow growing mass which may be pulsatile and have an audible bruit. Metastases to lungs, bone and brain are common and may occur many years after excision of the primary tumour [4,5]. The management of ASPS is mainly surgical with limited roles for both irradiation and chemotherapy [5]. Pre-operative knowledge of the very vascular nature of these tumours is of value to the surgeon. Unresectable tumour due to intraoperative haemorrhagic complications has been documented [6]. While a number of pathological reports have been published, few accounts of the imaging features of ASPS have appeared and this paper describes these appearances in a series of six-patients.
subsequently developed them. Cerebral metastases were noted in two patients. CT examinations were performed on a General Electric GE 8800 unit. Enhanced scans were done with a single bolus or bolus and infusion technique (36-45 g iodine dose) during scanning. Enhanced scan sequences were completed within 12 min of bolus completion. M R I examinations were carried out on a Siemens Magnetom 1 Tesla unit with Tl-weighted (SE 600/15-20) and T2-weighted (SE 2000/80) sequences. RESULTS
Primary Lesions Plain film studies revealed a soft tissue mass at the primary site in only one patient and no bone erosion was seen. US demonstrated a non-specific mixed echotexture or hypoechoic mass (Fig. 1) in four patients with well defined margins in only one of these. Large blood vessels were seen in all four tumours (Fig. 2) with a hypervascular appearance on colour Doppler in three. Continuous irregular high systolic and diastolic flow was detected on
PATIENTS AND M E T H O D S A review was carried out of the case records and imaging studies of six patients with histopathologically proven ASPS who were referred to our hospital over a 7 year period. Three were male and three female, age range 19-40 years (average 30 years). Five of these presented with a mass lesion (three thigh, one pelvis, one calf) and one with haemoptysis from pulmonary metastases, having had an ASPS tumour resected from the buttock 10 years previously. Two other patients also had lung metastases at presentation and a further two patients Correspondence to: Dr H. Cheung, Department of Diagnostic Radiologyand Organ Imaging, Prince of Wales Hospital, Shatin, NT, Hong Kong. Current addresses: *AcademicDepartment of Radiology,University of Sheffield, Royal Hallamshire Hospital, Sheffield, UK; tRadiology Department, District General Hospital, Rotherham, UK.
Fig. 1 - Longitudinal US image of large partially encapsulated mixed echotexture ASPS tumour within the quadriceps muscle group. Anterior margin of the femur(blackarrows), echogeniccapsuleof the tumour (white arrows).
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Fig. 4 CT scan o f a markedly enhancing necrotic ASPS tumour infiltrating the left quadriceps group and adductor longus muscle.
Fig, 2 - U S image of anechoic blood vessels (arrows) within same tumour as in Fig. 1.
spectral analysis (Fig. 3). CT demonstrated a low attenuation mass in only one of two unenhanced scans but showed a vigorously enhancing tumour in all four cases examined with contrast enhancement. Enlarged draining veins were noted in two of those studies. The tumour appeared well defined in only one CT study and both muscle infiltration and a necrotic core was seen in three (Fig. 4). M R ! of one primary lesion showed a high signal mass on Tl-weighted (T1-W) and very high signal on T2weighted (T2-W) sequences with evidence of muscle plane invasion. Tubular areas of signal void within the tumour on both T1-W and T2-W images were typical of rapid blood flow in enlarged vessels (Fig. 5). Angiography in one patient showed a hypervascular mass with multiple enlarged tortuous vessels, prolonged tumour stain and early draining veins (Fig. 6). Metastatic Disease
Chest radiographs showed pulmonary metastases in two of five patients on presentation but CT of the thorax subsequently demonstrated metastases not seen on initial chest films in three others. Cranial CT scans demonstrated recurrent haemorrhagic cerebral metastases in one patient and necrotic metastases in another. Two cranial M R scans in one patient showed evidence of subacute h a e m a t o m a within cerebral and cerebellar metastases with enlarged tumour vessels being shown as areas of signal void on both T1-W and T2-W images (Fig. 7).
DISCUSSION
Fig. 3 - Doppler spectrum of continuous turbulent high systolic and diastolic flow within ASPS tumour vessels.
The plain film findings of ASPS in our series showed no specific features. Chest radiographs detected typical pulmonary metastases in two patients at presentation but CT of the thorax was more sensitive in three others and should play a role in surveillance against the high risk of pulmonary spread, preferably with annual screening for an indefinite period. US showed variable encapsulation and echo pattern in four of the six patients (Fig. 1). Multiple enlarged blood vessels were noted in all of these with concordant spectral Doppler findings in three (Figs 2, 3). Lorigan e t al. [7] have previously reported non-specific US appearances in two cases. This study emphasizes the marked vascularity of ASPS on Doppler US and such findings may narrow
ALVEOLAR SOFT PART SARCOMA
255
(a)
Fig. 6 - Arterial phase of angiogram o f an ASPS tumour in the lower thigh showing multiple enlarged serpiginous vessels and dense tumour stain with early draining veins (arrows).
(b) Fig. 5 - (a) Axial TI-W (SE 600/15) and (b) coronal T2-W (SE 2000/80) M R images of ASPS within the anterior tibial compartment. High T1-W and very high T2-W signal is seen within the tumour in addition to signal void within enlarged tortuous tumour vessels (arrows). M, Medial; L, lateral.
the differential diagnosis of a non-specific soft tissue mass.
CT identified a vigorously enhancing mass in all four primary tumours in our study though one primary was a poorly detectable 4 cm diameter isodense lesion on an
initial unenhanced study. Lorigan et al. [7] noted that ASPS was hypodense on unenhanced CT compared to surrounding muscle in four of five patients. That same study surprisingly also found three primary ASPS which were isodense to skeletal muscle on contrast CT though all nine tumours imaged by angiography or CT were shown to be hypervascular on at least one of the two modalities. We feel that primary ASPS lesions could be overlooked without intravenous contrast and that a postcontrast study should always be performed. Previous CT reports of ASPS have not commented upon the margin of the tumour which was noted to be poorly defined at least in part in three of four primary lesions examined in our study (Fig. 4). This correlates with the incomplete encapsulation seen on pathological examination of m a n y ASPS tumours [1,2]. Only one of our patients had angiography of a primary tumour which showed a hypervascular mass and early draining veins (Fig. 6) similar to cases reported previously [8,9]. These angiographic appearances are non-specific and can be misdiagnosed as an arteriovenous malformation, angiosarcoma or synovial sarcoma [8,10,11]. Indeed
256
CLINICAL RADIOLOGY cerebral a n d cerebellar metastases (Fig. 7) a n d this previously u n r e p o r t e d finding concurs with the angiographic a p p e a r a n c e s o f such i n t r a c r a n i a l deposits n o t e d by R o s e n b a u m e t al. [15]. The D o p p l e r US, CT, M R I a n d a n g i o g r a p h y findings in our study have emphasized the very vascular n a t u r e o f ASPS t u m o u r s . D o p p l e r US a n d M R evidence o f multiple enlarged t u m o u r vessels with high b l o o d flow in both p r i m a r y a n d m e t a s t a t i c lesions has n o t been described previously. T o g e t h e r with the bright appearances o f the p r i m a r y t u m o u r o n b o t h T 1 - W a n d T 2 - W weighted M R i m a g i n g these radiological features m a y lead to early diagnosis of A S P S especially where the clinical present a t i o n is that o f a slow growing pelvic or lower limb mass in a y o u n g adult patient.
Acknowledgements. We thank Miss Irene Fu for preparation of the manuscript and Miss Alice Orh and Mr Thomas Fung for the illustrations.
REFERENCES
Fig. 7 Axial T1-W (SE 600/20) MR image of ASPS metastasis in the tip of the right cerebellar hemisphere with oedematous compression of the 4th ventricle(large arrow). Enlarged tortuous vesselssimilar to those seen in primary ASPS tumours (small arrows). histologically the t u m o u r m a y be m i s t a k e n for a paraganglioma, m y o b l a s t o m a or vascular metastasis [2,12]. The high signal on T I - W images with very high signal o n T 2 - W scans seen o n M R in one p r i m a r y ASPS t u m o u r in o u r study is p r o b a b l y due to slow b l o o d flow in some t u m o u r vessels (Fig. 5). This a p p e a r a n c e a l o n g with the signal void due to rapid flow within other t u m o u r vessels correlates with the a p p e a r a n c e s seen in two p r i m a r y lesions reported by L o r i g a n e t al. [7]. These a u t h o r s have p o i n t e d out that soft tissue sarcomas are usually isointense with respect to skeletal muscle o n T 1 - W images [13,14]. The u n u s u a l high T 1 - W signal a n d enlarged t u m o u r vessels seen b o t h in this study a n d that of L o r i g a n ' s g r o u p m a y prove to be suggestive M R findings o f ASPS, a l t h o u g h similar findings are to be expected from a r t e r i o v e n o u s m a l f o r m a t i o n s . The tendency o f ASPS metastases to bleed was shown o n two cranial C T studies a n d two M R scans which d e m o n s t r a t e d recurrent h a e m o r r h a g i c metastases in one patient. M R also showed enlarged t u m o u r vessels within
1 Smetana HF, Scott MW. Malignant tumours of non-chromaffin paraganglia. Military Surgery 1951;109:330-349. 2 Christopherson WM, Foote FW, Stewart FW. Alveolar soft part sarcomas. Cancer 1952;5:100-111. 3 Auerbach HE, Brooks JJ. Alveolar soft part sarcoma. Cancer 1987;60:66 73. 4 Liebermann PH, Foote FW, Stewart FW, Berg JW. Alveolar soft part sarcoma. Journal of the American Medical Association 1966;198:1047 1051. 5 Liebermann PH, Brennan MF, Kimmel M, Erlandson RA, GarinChesa P, Flehinger BY. Alveolar soft part sarcoma. A clinicopathologic study of half a century. Cancer 1989;63:1-13. 6 UdekwuFA, Pulvertaft RJ. Studiesof an alveolar soft part sarcoma. British Journal of Cancer 1965;19:744-748. 7 Lorigan JG, O'Keefe FN, Evans HL, Wallace S. The radiologic manifestations of alveolar soft part sarcoma. American Journal o[ Roentgenology 1989;153:335 339. 8 AsvallJ, Hoeg K, Kleppe K, Prydz PE. Alveolar soft part sarcoma. Clinical Radiology 1969;20:426-432. 9 Bateson EM. Radiological observation on an alveolar soft part sarcoma complicated by trauma and myositis ossificans. Clinical Radiology 1968;19:389 393. 10 Tegtmeyer CJ. Angiography of bones, joints and soft tissues. In: Abrams HL, ed. Abrams angiography. Boston: Little Brown, 1983:1959 1970. 11 Lo CM, Yeung HY, Siu KF. Misdiagnosedlocalised arteriovenous malformation. Journal of Vascular Surgery 1987;6:419-421. 12 Hurley JV. Alveolar soft part sarcoma. Australian andNew Zealand Journal of Surgery 1956;26:122-127. 13 PetesnickJP, Turner DA, Charters JR, Gitelis S, Zacharias CE. Soft tissue masses of the locomotor system: comparison of MR imaging with CT. Radiology 1986;160:125-133. 14 Pettersson H, GillespyT, Hamlin DJ, Enneking WF, SpringfieldDS, Andrew ER et al. Primary musculoskeletal turnouts: examination with MR imaging compared with conventional modalities. Radiology 1987;164:237-244. 15 Rosenbaum AE, Gabrielsen TO, Harris H, Goldberg S. Cerebral manifestations of alveolar soft part sarcoma. Radiology 1971;99:109 115.
Imaging of Alveolar Soft Part Sarcoma B. D. D A L Y , H. C H E U N G , P. A. GAINES*, M. J. B R A D L E Y t and C. M E T R E W E L I
Department of Diagnostic' Radiology and Organ Imaging, Chinese University, Prince of Wales Hospital, Hong Kong The imaging investigations in six patients with alveolar soft part sarcoma (ASPS) are reviewed. Five patients presented with a pelvic or lower limb mass and one with haemoptysis from pulmonary metastases. Magnetic resonance imaging (MRI), CT, Doppler US and angiography studies demonstrated the highly vascular nature of this rare tumour and the frequent occurrence of pulmonary and intracranial metastases. Previously unreported Doppler US and MR evidence of multiple enlarged vessels and high blood flow within primary and secondary ASPS tumours is emphasized. Imaging is of considerable importance both for pre-operative localization and long term surveillance of this slow growing but invariably disseminating tumour. Daly, B.D., Cheung, H., Gaines, P.A., Bradley, M.J. & Metreweli, C. (1992).
Clinical Radiology 46, 253-256. Imaging of Alveolar Soft Part Sarcoma Accepted for Publication 8 May 1992
Alveolar soft part sarcoma (ASPS) is a highly vascular malignant tumour which occurs most often in the soft tissues of the pelvis and lower limbs. It is rare, being one of the least frequently detected sarcomas and the pathological appearances were first recognized by Smetana and Scott in 1951 [1]. The cell of origin is as yet unknown and debated but the arrangement of cells on histopathological examination mimics that of the respiratory alveoli and hence the descriptive name [2,3]. ASPS is seen in all races, most frequently in young adults and usually presents clinically as a slow growing mass which may be pulsatile and have an audible bruit. Metastases to lungs, bone and brain are common and may occur many years after excision of the primary tumour [4,5]. The management of ASPS is mainly surgical with limited roles for both irradiation and chemotherapy [5]. Pre-operative knowledge of the very vascular nature of these tumours is of value to the surgeon. Unresectable tumour due to intraoperative haemorrhagic complications has been documented [6]. While a number of pathological reports have been published, few accounts of the imaging features of ASPS have appeared and this paper describes these appearances in a series of six-patients.
subsequently developed them. Cerebral metastases were noted in two patients. CT examinations were performed on a General Electric GE 8800 unit. Enhanced scans were done with a single bolus or bolus and infusion technique (36-45 g iodine dose) during scanning. Enhanced scan sequences were completed within 12 min of bolus completion. M R I examinations were carried out on a Siemens Magnetom 1 Tesla unit with Tl-weighted (SE 600/15-20) and T2-weighted (SE 2000/80) sequences. RESULTS
Primary Lesions Plain film studies revealed a soft tissue mass at the primary site in only one patient and no bone erosion was seen. US demonstrated a non-specific mixed echotexture or hypoechoic mass (Fig. 1) in four patients with well defined margins in only one of these. Large blood vessels were seen in all four tumours (Fig. 2) with a hypervascular appearance on colour Doppler in three. Continuous irregular high systolic and diastolic flow was detected on
PATIENTS AND M E T H O D S A review was carried out of the case records and imaging studies of six patients with histopathologically proven ASPS who were referred to our hospital over a 7 year period. Three were male and three female, age range 19-40 years (average 30 years). Five of these presented with a mass lesion (three thigh, one pelvis, one calf) and one with haemoptysis from pulmonary metastases, having had an ASPS tumour resected from the buttock 10 years previously. Two other patients also had lung metastases at presentation and a further two patients Correspondence to: Dr H. Cheung, Department of Diagnostic Radiologyand Organ Imaging, Prince of Wales Hospital, Shatin, NT, Hong Kong. Current addresses: *AcademicDepartment of Radiology,University of Sheffield, Royal Hallamshire Hospital, Sheffield, UK; tRadiology Department, District General Hospital, Rotherham, UK.
Fig. 1 - Longitudinal US image of large partially encapsulated mixed echotexture ASPS tumour within the quadriceps muscle group. Anterior margin of the femur(blackarrows), echogeniccapsuleof the tumour (white arrows).
254
CLINICAL RADIOLOGY
Fig. 4 CT scan o f a markedly enhancing necrotic ASPS tumour infiltrating the left quadriceps group and adductor longus muscle.
Fig, 2 - U S image of anechoic blood vessels (arrows) within same tumour as in Fig. 1.
spectral analysis (Fig. 3). CT demonstrated a low attenuation mass in only one of two unenhanced scans but showed a vigorously enhancing tumour in all four cases examined with contrast enhancement. Enlarged draining veins were noted in two of those studies. The tumour appeared well defined in only one CT study and both muscle infiltration and a necrotic core was seen in three (Fig. 4). M R ! of one primary lesion showed a high signal mass on Tl-weighted (T1-W) and very high signal on T2weighted (T2-W) sequences with evidence of muscle plane invasion. Tubular areas of signal void within the tumour on both T1-W and T2-W images were typical of rapid blood flow in enlarged vessels (Fig. 5). Angiography in one patient showed a hypervascular mass with multiple enlarged tortuous vessels, prolonged tumour stain and early draining veins (Fig. 6). Metastatic Disease
Chest radiographs showed pulmonary metastases in two of five patients on presentation but CT of the thorax subsequently demonstrated metastases not seen on initial chest films in three others. Cranial CT scans demonstrated recurrent haemorrhagic cerebral metastases in one patient and necrotic metastases in another. Two cranial M R scans in one patient showed evidence of subacute h a e m a t o m a within cerebral and cerebellar metastases with enlarged tumour vessels being shown as areas of signal void on both T1-W and T2-W images (Fig. 7).
DISCUSSION
Fig. 3 - Doppler spectrum of continuous turbulent high systolic and diastolic flow within ASPS tumour vessels.
The plain film findings of ASPS in our series showed no specific features. Chest radiographs detected typical pulmonary metastases in two patients at presentation but CT of the thorax was more sensitive in three others and should play a role in surveillance against the high risk of pulmonary spread, preferably with annual screening for an indefinite period. US showed variable encapsulation and echo pattern in four of the six patients (Fig. 1). Multiple enlarged blood vessels were noted in all of these with concordant spectral Doppler findings in three (Figs 2, 3). Lorigan e t al. [7] have previously reported non-specific US appearances in two cases. This study emphasizes the marked vascularity of ASPS on Doppler US and such findings may narrow
ALVEOLAR SOFT PART SARCOMA
255
(a)
Fig. 6 - Arterial phase of angiogram o f an ASPS tumour in the lower thigh showing multiple enlarged serpiginous vessels and dense tumour stain with early draining veins (arrows).
(b) Fig. 5 - (a) Axial TI-W (SE 600/15) and (b) coronal T2-W (SE 2000/80) M R images of ASPS within the anterior tibial compartment. High T1-W and very high T2-W signal is seen within the tumour in addition to signal void within enlarged tortuous tumour vessels (arrows). M, Medial; L, lateral.
the differential diagnosis of a non-specific soft tissue mass.
CT identified a vigorously enhancing mass in all four primary tumours in our study though one primary was a poorly detectable 4 cm diameter isodense lesion on an
initial unenhanced study. Lorigan et al. [7] noted that ASPS was hypodense on unenhanced CT compared to surrounding muscle in four of five patients. That same study surprisingly also found three primary ASPS which were isodense to skeletal muscle on contrast CT though all nine tumours imaged by angiography or CT were shown to be hypervascular on at least one of the two modalities. We feel that primary ASPS lesions could be overlooked without intravenous contrast and that a postcontrast study should always be performed. Previous CT reports of ASPS have not commented upon the margin of the tumour which was noted to be poorly defined at least in part in three of four primary lesions examined in our study (Fig. 4). This correlates with the incomplete encapsulation seen on pathological examination of m a n y ASPS tumours [1,2]. Only one of our patients had angiography of a primary tumour which showed a hypervascular mass and early draining veins (Fig. 6) similar to cases reported previously [8,9]. These angiographic appearances are non-specific and can be misdiagnosed as an arteriovenous malformation, angiosarcoma or synovial sarcoma [8,10,11]. Indeed
256
CLINICAL RADIOLOGY cerebral a n d cerebellar metastases (Fig. 7) a n d this previously u n r e p o r t e d finding concurs with the angiographic a p p e a r a n c e s o f such i n t r a c r a n i a l deposits n o t e d by R o s e n b a u m e t al. [15]. The D o p p l e r US, CT, M R I a n d a n g i o g r a p h y findings in our study have emphasized the very vascular n a t u r e o f ASPS t u m o u r s . D o p p l e r US a n d M R evidence o f multiple enlarged t u m o u r vessels with high b l o o d flow in both p r i m a r y a n d m e t a s t a t i c lesions has n o t been described previously. T o g e t h e r with the bright appearances o f the p r i m a r y t u m o u r o n b o t h T 1 - W a n d T 2 - W weighted M R i m a g i n g these radiological features m a y lead to early diagnosis of A S P S especially where the clinical present a t i o n is that o f a slow growing pelvic or lower limb mass in a y o u n g adult patient.
Acknowledgements. We thank Miss Irene Fu for preparation of the manuscript and Miss Alice Orh and Mr Thomas Fung for the illustrations.
REFERENCES
Fig. 7 Axial T1-W (SE 600/20) MR image of ASPS metastasis in the tip of the right cerebellar hemisphere with oedematous compression of the 4th ventricle(large arrow). Enlarged tortuous vesselssimilar to those seen in primary ASPS tumours (small arrows). histologically the t u m o u r m a y be m i s t a k e n for a paraganglioma, m y o b l a s t o m a or vascular metastasis [2,12]. The high signal on T I - W images with very high signal o n T 2 - W scans seen o n M R in one p r i m a r y ASPS t u m o u r in o u r study is p r o b a b l y due to slow b l o o d flow in some t u m o u r vessels (Fig. 5). This a p p e a r a n c e a l o n g with the signal void due to rapid flow within other t u m o u r vessels correlates with the a p p e a r a n c e s seen in two p r i m a r y lesions reported by L o r i g a n e t al. [7]. These a u t h o r s have p o i n t e d out that soft tissue sarcomas are usually isointense with respect to skeletal muscle o n T 1 - W images [13,14]. The u n u s u a l high T 1 - W signal a n d enlarged t u m o u r vessels seen b o t h in this study a n d that of L o r i g a n ' s g r o u p m a y prove to be suggestive M R findings o f ASPS, a l t h o u g h similar findings are to be expected from a r t e r i o v e n o u s m a l f o r m a t i o n s . The tendency o f ASPS metastases to bleed was shown o n two cranial C T studies a n d two M R scans which d e m o n s t r a t e d recurrent h a e m o r r h a g i c metastases in one patient. M R also showed enlarged t u m o u r vessels within
1 Smetana HF, Scott MW. Malignant tumours of non-chromaffin paraganglia. Military Surgery 1951;109:330-349. 2 Christopherson WM, Foote FW, Stewart FW. Alveolar soft part sarcomas. Cancer 1952;5:100-111. 3 Auerbach HE, Brooks JJ. Alveolar soft part sarcoma. Cancer 1987;60:66 73. 4 Liebermann PH, Foote FW, Stewart FW, Berg JW. Alveolar soft part sarcoma. Journal of the American Medical Association 1966;198:1047 1051. 5 Liebermann PH, Brennan MF, Kimmel M, Erlandson RA, GarinChesa P, Flehinger BY. Alveolar soft part sarcoma. A clinicopathologic study of half a century. Cancer 1989;63:1-13. 6 UdekwuFA, Pulvertaft RJ. Studiesof an alveolar soft part sarcoma. British Journal of Cancer 1965;19:744-748. 7 Lorigan JG, O'Keefe FN, Evans HL, Wallace S. The radiologic manifestations of alveolar soft part sarcoma. American Journal o[ Roentgenology 1989;153:335 339. 8 AsvallJ, Hoeg K, Kleppe K, Prydz PE. Alveolar soft part sarcoma. Clinical Radiology 1969;20:426-432. 9 Bateson EM. Radiological observation on an alveolar soft part sarcoma complicated by trauma and myositis ossificans. Clinical Radiology 1968;19:389 393. 10 Tegtmeyer CJ. Angiography of bones, joints and soft tissues. In: Abrams HL, ed. Abrams angiography. Boston: Little Brown, 1983:1959 1970. 11 Lo CM, Yeung HY, Siu KF. Misdiagnosedlocalised arteriovenous malformation. Journal of Vascular Surgery 1987;6:419-421. 12 Hurley JV. Alveolar soft part sarcoma. Australian andNew Zealand Journal of Surgery 1956;26:122-127. 13 PetesnickJP, Turner DA, Charters JR, Gitelis S, Zacharias CE. Soft tissue masses of the locomotor system: comparison of MR imaging with CT. Radiology 1986;160:125-133. 14 Pettersson H, GillespyT, Hamlin DJ, Enneking WF, SpringfieldDS, Andrew ER et al. Primary musculoskeletal turnouts: examination with MR imaging compared with conventional modalities. Radiology 1987;164:237-244. 15 Rosenbaum AE, Gabrielsen TO, Harris H, Goldberg S. Cerebral manifestations of alveolar soft part sarcoma. Radiology 1971;99:109 115.
