1991, The British Journal of Radiology, 64, 1163-1164
Case of the month Mistaken identity of a neck mass By M. J . Warren, BSc, MRCP, FRCR and \ J . Walton, BSc Department of Radiology and *Nuffield Department of Surgery, Vascular Research Laboratory, John Radcliffe Hospital, Headington, Oxford 0X3 9DU, UK {Received August 1990 and in revised form December 1990)
A 64-year-old woman presented at another hospital with a 4 year history of an asymptomatic left sided neck mass. On examination it was firm, non-tender and nonAddress correspondence to: Dr M. J. Warren, Department of Radiology, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
Figure 1. CT with intravenous enhancement at the level of C4 vertebra.
Vol. 64, No. 768
pulsatile. In addition she had an enlarged left tonsil. Computed tomography (CT) was performed (Fig. 1). Following a left tonsillectomy surgical exploration of the neck was commenced. This was abandoned because of haemorrhage and the patient was referred for further investigation. B-mode ultrasound showed an inhomogeneous mass of medium intensity echoes, splaying the left internal and external carotid arteries at the bifurcation. Doppler shift frequency signals were sampled at multiple sites within the tumour using two duplex machines (Acuson 128 5 MHz, Diasonics DRF 400 4.5 MHz). Figure 2 shows a representative recording. What is the most likely diagnosis?
Figure 2. Duplex sonography of the neck mass, longitudinal section (Acuson 128).
1163
Keywords: Carotid body tumour, Computed tomography, Doppler ultrasound, Embolization
Figure 3. Digital subtraction angiogram left external carotid injection, lateral projection. An intensely hypervascular mass displaces the external carotid anteriorly.
On review CT showed a well defined homogeneous 3 cm mass in the left parapharyngeal space, extending from C1/2 to C4/5. The attenuation value was similar to that of adjacent muscle and enhancement of 50 HU occurred following an intravenous bolus of contrast (18.5 g of iodine). Common carotid angiography showed a highly vascular mass at the bifurcation characteristic of a carotid body tumour. Left external carotid angiography (Fig. 3) showed that the tumour was fed by multiple branches and the larger ones were embolized with Ivalon (polyvinyl alcohol sponge) prior to surgical resection. Histology confirmed the diagnosis and the tonsillectomy specimen showed benign hyperplasia. Discussion Carotid body tumour is one of the commoner nonchromaffin branchial paraganglionomas with a wide age distribution and no sex dominance. Multiple tumours occur in 15% of all cases and are more commonly of the familial type. Malignancy occurs in up to 15% but histological diagnosis is not definitive (Lasjaunias & Berenstein, 1987). The differential diagnosis of a mass at the carotid bifurcation includes pathologically enlarged lymph nodes (inflammatory, lymphomatous, metastatic), ectasia or aneurysm of the carotid arteries, carotid body tumour, branchial cyst and tumours of neurogenic origin (Lasjaunias & Berenstein, 1987). In most cases B-mode ultrasound will distinguish solid tumours from branchial cysts and great vessel aneurysms. However, branchial cysts may be complex,
1164
Case of the month
containing debris, and schwannomas may contain cystic areas. The ultrasonic appearance of the solid tumours is non-specific and duplex Doppler ultrasound has been advocated as a method of differentiation. Gritzmann et al (1987) using a 5 MHz probe recorded Doppler shift, indicating blood flow in three carotid body tumours; but no signal was obtained from cervical lymph node metastases. On the contrary, Mountford and Atkinson (1979) recorded Doppler shift (10 MHz probe) in pathologically enlarged lymph nodes. In our case no Doppler signal was detected in the carotid body tumour, belying its true vascularity. Unfortunately, colour flow Doppler, which is more sensitive, was unavailable. Our case illustrates that the absence of a Doppler signal in a tumour does not necessarily indicate avascularity. Slow blood flow below the minimum threshold for detection may still be present. Similarly, the assessment of the vascularity of enhancing neck masses on CT is not clear-cut. Enhancement may reflect either high vascular flow or gradual extravascular accumulation of contrast, especially when an infusion technique is used. As a result enlarged lymph nodes, neuromas and carotid body tumours may all appear to enhance to a similar extent as major vessels (Som et al, 1985). In this case the CT appearance had originally been interpreted as lymphadenopathy (possibly metastatic in view of the tonsillar enlargement). This pitfall might have been avoided if dynamic CT, as advocated by Som et al (1985), had been performed. Carotid body tumour embolization may be performed either in patients unsuitable for surgery or to reduce tumour vascularity pre-operatively (Lasjaunias & Berenstein, 1987). Embolization should only be performed by an experienced specialist to reduce the risk of complications, the most serious of which is stroke. Acknowledgments We thank Professor P. J. Morris for allowing us to report this case and Dr A. J. Molyneux for details of the embolization.
References GRITZMANN, N.,
HEROLD, C ,
HALLER, J.,
KARNEL, F.
&
SCHWAIGHOFER, B., 1987. Duplex sonography of tumours of the carotid body. Cardiovascular and Interventional Radiology, 10, 280-284. LASJAUNIAS, P. & BERENSTEIN, A., 1987. Surgical Neuroangio-
graphy, Vol. 2, Endovascular Treatment of Craniofacial Lesions. (Springer-Verlag, Berlin, Heidelberg, New York), pp. 127-162. MOUNTFORD, R. A. & ATKINSON, P., 1979. Doppler ultrasound
examination of pathologically enlarged lymph nodes. British Journal of Radiology, 52, 464-467. SOM, P. M.,
LANZIERI, C. F., SACHER, M.,
LAWSON, W.
&
BILLER, H. F., 1985. Extracranial tumour vascularity; determination by dynamic CT scanning Part II: The Unit Approach. Radiology, 154, 407-412.
The British Journal of Radiology, December 1991
Case of the month Mistaken identity of a neck mass By M. J . Warren, BSc, MRCP, FRCR and \ J . Walton, BSc Department of Radiology and *Nuffield Department of Surgery, Vascular Research Laboratory, John Radcliffe Hospital, Headington, Oxford 0X3 9DU, UK {Received August 1990 and in revised form December 1990)
A 64-year-old woman presented at another hospital with a 4 year history of an asymptomatic left sided neck mass. On examination it was firm, non-tender and nonAddress correspondence to: Dr M. J. Warren, Department of Radiology, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK.
Figure 1. CT with intravenous enhancement at the level of C4 vertebra.
Vol. 64, No. 768
pulsatile. In addition she had an enlarged left tonsil. Computed tomography (CT) was performed (Fig. 1). Following a left tonsillectomy surgical exploration of the neck was commenced. This was abandoned because of haemorrhage and the patient was referred for further investigation. B-mode ultrasound showed an inhomogeneous mass of medium intensity echoes, splaying the left internal and external carotid arteries at the bifurcation. Doppler shift frequency signals were sampled at multiple sites within the tumour using two duplex machines (Acuson 128 5 MHz, Diasonics DRF 400 4.5 MHz). Figure 2 shows a representative recording. What is the most likely diagnosis?
Figure 2. Duplex sonography of the neck mass, longitudinal section (Acuson 128).
1163
Keywords: Carotid body tumour, Computed tomography, Doppler ultrasound, Embolization
Figure 3. Digital subtraction angiogram left external carotid injection, lateral projection. An intensely hypervascular mass displaces the external carotid anteriorly.
On review CT showed a well defined homogeneous 3 cm mass in the left parapharyngeal space, extending from C1/2 to C4/5. The attenuation value was similar to that of adjacent muscle and enhancement of 50 HU occurred following an intravenous bolus of contrast (18.5 g of iodine). Common carotid angiography showed a highly vascular mass at the bifurcation characteristic of a carotid body tumour. Left external carotid angiography (Fig. 3) showed that the tumour was fed by multiple branches and the larger ones were embolized with Ivalon (polyvinyl alcohol sponge) prior to surgical resection. Histology confirmed the diagnosis and the tonsillectomy specimen showed benign hyperplasia. Discussion Carotid body tumour is one of the commoner nonchromaffin branchial paraganglionomas with a wide age distribution and no sex dominance. Multiple tumours occur in 15% of all cases and are more commonly of the familial type. Malignancy occurs in up to 15% but histological diagnosis is not definitive (Lasjaunias & Berenstein, 1987). The differential diagnosis of a mass at the carotid bifurcation includes pathologically enlarged lymph nodes (inflammatory, lymphomatous, metastatic), ectasia or aneurysm of the carotid arteries, carotid body tumour, branchial cyst and tumours of neurogenic origin (Lasjaunias & Berenstein, 1987). In most cases B-mode ultrasound will distinguish solid tumours from branchial cysts and great vessel aneurysms. However, branchial cysts may be complex,
1164
Case of the month
containing debris, and schwannomas may contain cystic areas. The ultrasonic appearance of the solid tumours is non-specific and duplex Doppler ultrasound has been advocated as a method of differentiation. Gritzmann et al (1987) using a 5 MHz probe recorded Doppler shift, indicating blood flow in three carotid body tumours; but no signal was obtained from cervical lymph node metastases. On the contrary, Mountford and Atkinson (1979) recorded Doppler shift (10 MHz probe) in pathologically enlarged lymph nodes. In our case no Doppler signal was detected in the carotid body tumour, belying its true vascularity. Unfortunately, colour flow Doppler, which is more sensitive, was unavailable. Our case illustrates that the absence of a Doppler signal in a tumour does not necessarily indicate avascularity. Slow blood flow below the minimum threshold for detection may still be present. Similarly, the assessment of the vascularity of enhancing neck masses on CT is not clear-cut. Enhancement may reflect either high vascular flow or gradual extravascular accumulation of contrast, especially when an infusion technique is used. As a result enlarged lymph nodes, neuromas and carotid body tumours may all appear to enhance to a similar extent as major vessels (Som et al, 1985). In this case the CT appearance had originally been interpreted as lymphadenopathy (possibly metastatic in view of the tonsillar enlargement). This pitfall might have been avoided if dynamic CT, as advocated by Som et al (1985), had been performed. Carotid body tumour embolization may be performed either in patients unsuitable for surgery or to reduce tumour vascularity pre-operatively (Lasjaunias & Berenstein, 1987). Embolization should only be performed by an experienced specialist to reduce the risk of complications, the most serious of which is stroke. Acknowledgments We thank Professor P. J. Morris for allowing us to report this case and Dr A. J. Molyneux for details of the embolization.
References GRITZMANN, N.,
HEROLD, C ,
HALLER, J.,
KARNEL, F.
&
SCHWAIGHOFER, B., 1987. Duplex sonography of tumours of the carotid body. Cardiovascular and Interventional Radiology, 10, 280-284. LASJAUNIAS, P. & BERENSTEIN, A., 1987. Surgical Neuroangio-
graphy, Vol. 2, Endovascular Treatment of Craniofacial Lesions. (Springer-Verlag, Berlin, Heidelberg, New York), pp. 127-162. MOUNTFORD, R. A. & ATKINSON, P., 1979. Doppler ultrasound
examination of pathologically enlarged lymph nodes. British Journal of Radiology, 52, 464-467. SOM, P. M.,
LANZIERI, C. F., SACHER, M.,
LAWSON, W.
&
BILLER, H. F., 1985. Extracranial tumour vascularity; determination by dynamic CT scanning Part II: The Unit Approach. Radiology, 154, 407-412.
The British Journal of Radiology, December 1991
