British Journal of Radiology (2004) 77, 600-606
© 2004 British Institute of Radiology
doi: 10.1259/bjr/15671187
Vascular lesions of parotid gland in adult patients: diagnosis with high-resolution ultrasound and MRI
K T Wong, FRCR,
A T Ahuja, FRCR,
A D King, FRCR,
E H Y Yuen, FRCR and
S C H Yu, FRCR
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong SAR
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Abstract
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Three adult patients with rare vascular lesions in the parotid gland including pseudoaneurysm, arteriovenous fistula and haemangioma are discussed. All patients presented with non-specific unilateral parotid mass. In all cases high-resolution ultrasound and MRI allowed accurate diagnosis and delineation of the extent of lesion. Conventional angiogram was utilized for planning definitive surgical or endovascular treatment.
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Introduction
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Vascular lesions are rarely encountered within parotid glands in adults. There are isolated case reports describing mainly the angiographic findings of these rare parotid vascular lesions. We present three cases of parotid vascular lesions including pseudoaneurysm, arteriovenous fistula (AVF) and haemangioma with particular emphasis on the role of high-resolution ultrasound and MRI in making an accurate diagnosis and assessment of extent of involvement.
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Case reports
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Case 1
A 75-year-old man presented with a palpable mass over the left parotid region for 2 months. The mass fluctuated in size during this period and there was mild associated pain over that region. There was no previous history of surgery or trauma. Physical examination revealed a 2 cm firm mass in the left parotid region. The overlying skin was normal with no discolouration and facial nerve function was intact. The rest of examination of the neck was unremarkable. The clinical diagnosis suggested was a benign parotid tumour such as Warthin's tumour.
Ultrasound examination using high-frequency linear transducer (5–12 MHz) (ATL HDI 5000, Phillips Ultrasound, USA) showed a 2 cm round heterogeneous hypoechoic mass with well-defined margins involving both deep and superficial lobes of left parotid gland. There was internal calcification and cystic spaces within the lesion (Figure 1a
). On power Doppler ultrasound, colour flow was demonstrated within the cystic spaces. There was a supplying artery deep to the parotid lesion with blood jetting into the cystic spaces (Figure 1b).
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Figure 1. 75-year-old man with pseudoaneurysm in the left parotid gland. (a) Transverse grey-scale ultrasound of the left parotid gland shows a well-circumscribed hypoechoic heterogeneous mass with internal "cystic" spaces (arrows) and calcification (arrowheads). (b) Transverse power Doppler ultrasound of the left parotid gland reveals the presence of colour flow within "cystic" spaces and a supplying artery (arrow) deep to the left parotid mass. (c) Axial spin-echo T1 weighted MRI (450 ms/13 ms/2 [repetition time/echo time/number of signal averaging]) shows a well-circumscribed mass (arrows) with signal intensity similar to muscle centred in the deep lobe. (d) Coronal post-gadolinium fat-suppressed spin-echo T1 weighted MRI (520/13/2) shows avid homogeneous enhancement of the lesion. (e) Digital subtraction angiogram of left external carotid artery (lateral projection) confirms a pseudoaneurysm (arrow) with slightly lobulated outline arising from the distal portion of posterior auricular artery (arrowhead). (f) Magnified digital subtraction external carotid arteriogram (lateral projection) shows successful embolisation of the posterior auricular artery by fibred microcoil. Note absence of contrast filling of the aneurysmal sac after the procedure.
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MRI using 1.5 Tesla scanner (Gyroscan ACS, Phillips Medical System, Best, Netherlands) showed a well-circumscribed lesion centred at the deep lobe of left parotid gland which was isointense on T1 weighted, hyperintense on T2 weighted scans and with avid homogeneous enhancement after intravenous gadolinium (Figures 1c,d
).
The overall ultrasound and MRI appearances were suggestive of a pseudoaneurysm within the left parotid gland. Digital subtraction angiography (DSA) was performed for delineation of the exact vascular anatomy to help plan further treatment. Selective left external carotid arteriogram confirmed the presence of a pseudoaneurysm arising from the distal left posterior auricular artery (Figure 1e), which was successfully embolised by three straight fibred microcoils proximal to the site of aneurysm (Figure 1f). The patient remained asymptomatic 3 months after the procedure, with a small area of skin induration left over the left parotid area.
Case 2
A 57-year-old woman presented with swelling over the left parotid region for 2–3 months. There was no recent history of surgery or trauma at this area. Physical examination showed a 2 cm pulsatile mass in the left parotid region. A palpable thrill and audible bruit were noted. Facial nerve function was intact and examination of the rest of neck was unremarkable. The clinical diagnosis suggested was a vascular abnormality probably with high flow within.
Ultrasound examination showed a 2.5 cm well-circumscribed cystic lesion with internal septations in the left parotid gland (Figure 2a). There were enlarged serpiginous vascular channels adjacent to the cystic lesion (Figure 2b). On power Doppler imaging, the lesion demonstrated marked intralesional flow with a central supplying vessel and enlarged draining vein connected to the external jugular vein. The ultrasound appearances were suggestive of an AVF. The diagnosis was substantiated by MRI, which showed numerous serpiginous signal voids within both superficial and deep lobes of left parotid gland (Figure 2c). On MR angiography, the lesion was fed by branches from external carotid artery. Venous drainage was predominantly via external jugular vein.
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Figure 2. 57-year-old woman with arteriovenous fistula in the left parotid gland. (a) Transverse grey-scale ultrasound of left parotid gland shows a well-circumscribed cystic lesion with internal septation involving both superficial and deep lobes (arrow). (b) Transverse grey-scale ultrasound of the left parotid region shows dilated and tortuous vascular channels in the vicinity of the lesion (arrows). (c) Axial fat-suppressed spin-echo T1 weighted MRI (520/13/4) shows conglomerate serpiginous signal void involving superficial and deep lobe of left parotid gland. (d) Digital subtraction left external carotid angiogram in anteroposterior projection. (e) Digital subtraction left external carotid angiogram in lateral projection. Numerous tortuous dilated veins in the left parotid region are shown (d, e) supplied by a hypertrophied feeder from external carotid artery (arrow) and drain into left external jugular vein (arrowhead). (f) Post-embolisation digital subtraction left external carotid angiogram in lateral projection shows complete obliteration of the arteriovenous fistula.
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DSA was performed with the intention of endovascular intervention. The AVF over the left parotid region was supplied by a single hypertrophied feeder from external carotid artery. The bulk of the vascular structures within the parotid gland were dilated draining veins of the AVF (Figures 2d,e). Successful embolisation was achieved with a 2 mm x 6 mm fibred Guglielmi detachable coil (GDC) after selective catheterization of the arterial feeder (Figure 2f). A small new AVF with progressive increase in flow from internal maxillary artery was detected after initial coil embolisation. This was successfully embolised with histoacryl–lipiodol mixture. The parotid mass progressively decreased in size and was barely palpable on 6 months' follow-up.
Case 3
A 35-year-old man who was an intravenous drug abuser presented with swelling over the right parotid region, which was increasing in size over the previous 3 months. There was no history of recent trauma or surgery. It was not painful and there was no associated fever. Physical examination revealed a soft mass in the right parotid region. The overlying skin appeared normal without any discolouration. No definite pulsation or palpable thrill was demonstrated. Examination of the rest of neck was unremarkable. No specific clinical diagnosis was made and imaging investigation was suggested.
Ultrasound examination showed a hypoechoic heterogeneous lesion with ill-defined margins involving both superficial and deep lobes of right parotid gland (Figure 3a). It comprised of septated sinusoidal spaces with slow flow demonstrated on real time grey scale imaging. Multiple echogenic foci casting posterior acoustic shadowing suggestive of phleboliths were seen within the lesion. Colour flow was seen within on power Doppler imaging. The ultrasound appearances were diagnostic of a haemangioma.
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Figure 3. 35-year-old man with haemangioma in the right parotid gland. (a) Transverse grey-scale ultrasound of the right parotid gland shows a heterogeneous hypoechoic mass (white arrows) with sinusoidal spaces (arrowheads) and phlebolith (black arrow). (b) Axial spin-echo T1 weighted MRI (450/13/2) shows a mass involving superficial and deep lobes (arrows) which shows signal intensity similar to muscle. (c) Fat-suppressed fast spin-echo T2 weighted MRI (2500/120/2) shows markedly hyperintense signal intensity of the right parotid mass. Internal small round (arrows) and serpiginous (arrowhead) signal voids represent phleboliths and small vessels within the lesion, respectively. A similar smaller lesion is seen in right submandibular region (white arrow). (d) Fat-suppressed spin-echo T1 weighted MRI (520/13/2) shows enhancement of the intraparotid lesion after intravenous gadolinium administration.(e) 99mTechnetium pertechnetate labelled red blood cell scan in anterior acquisition shows red cell sequestration in right parotid region (arrow). Smaller areas of red cell sequestration are also demonstrated in right submandibular region (arrowhead) and left tongue base (open arrow).
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On MRI the lesion was isointense on T1 weighted imaging, markedly hyperintense on T2 weighted imaging with avid enhancement after intravenous administration of gadolinium (Figures 3b,c,d). There were small rounded foci of signal void which were best seen on T2 weighted images compatible with phleboliths. Small serpiginous vessels were also demonstrated within the lesion. Two smaller lesions with similar signal characteristics were detected in right submandibular region and left tongue base.
The diagnosis of haemangiomas was further confirmed by subsequent radionuclide red blood cell scan (in vitro red blood cell labelling with 25 mCi 99mTechnetium pertechnetate) which showed abnormal red cell sequestration at the corresponding sites (Figure 3e).
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Discussion
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Parotid mass is a common clinical presentation for head and neck imaging. In adult patients benign tumours such as pleomorphic adenoma or Warthin's tumour are the most common diagnosis [1]. Vascular lesions are rarely considered in this age group. The three cases in this series highlight the ultrasound and MRI features of pseudoaneurysm, AVF and haemangioma of parotid gland.
Aneurysm involving external carotid artery and its branches are rare, constituting 0.4% to 4% of all aneurysms [2]. A few case reports have previously described aneurysms of the external carotid artery [3–6] and superficial temporal artery [7, 8] presenting as parotid swelling. The aetiology of these reported cases of pseudoaneurysms are mostly traumatic or mycotic in origin. To the best of our knowledge, pseudoaneurysm arising from the posterior auricular artery has not been previously reported. The cause of pseudoaneurysm in our case is likely idiopathic as there is no preceding history of trauma, surgery or evidence of infection in the parotid region.
High-resolution ultrasound supplemented by power Doppler study allows accurate diagnosis of a parotid pseudoaneurysm. The role of conventional angiogram is mainly for delineation of exact vascular anatomy prior to definitive treatment.
The location of the facial nerve and the vascular nature of pseudoaneurysm would increase the risk associated with surgical excision. Other treatment options such as endovascular embolisation have been previously used [3, 4]. Braun et al reviewed various techniques of endovascular occlusion [9] and concluded that coils were better than balloon because of the ability to use smaller catheters, the necessity for fewer catheter manipulations and the reduced likelihood of migration of the embolised material. In our case, in view of the small calibre and tortuosity of the posterior auricular artery, the parent artery proximal to the aneurysm was embolised with no inadvertent complications.
Most of the reported cases of AVF are spontaneous with no preceding history of trauma or surgery [10, 11]. On high-resolution ultrasound and MRI, the presence of dilated vascular channels with high flow allows for an accurate diagnosis of an AVF. MRI, in particular, helps to identify the origin of the feeding artery and where the dilated veins drain into. Conventional angiogram is therefore not routinely necessary for diagnosis. The role of selective angiography in planning endovascular treatment has been highlighted in literature [11] and endovascular balloon occlusion and surgical excision are the accepted modality of treatment. Successful embolisation with coils, to the best of our knowledge, has not been reported in the literature.
Benign haemangiomas are the most common tumours of parotid gland in children and the vast majority are found below the age of 1 year [12]. These are usually of cavernous type although capillary haemangiomas of parotid gland have been reported [13].
Imaging features of parotid haemangioma are similar to those in the rest of head and neck. Typically they are heterogeneous hypoechoic lesions with sinusoidal spaces, internal slow flow and phleboliths on ultrasound [14]. On MRI, marked T2 hyperintense signal and the presence of signal voids representing blood vessels and phleboliths are the hallmark features [15]. In our experience, confident diagnosis can be established for most cases of head and neck haemangiomas on good quality high-resolution ultrasound. The extent of involvement is better assessed by MRI, especially for deep-seated haemangiomas and the presence of intraosseous involvement. Conventional angiography is not necessary as majority of haemangiomas are of slow flow and endovascular treatment is not useful.
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Conclusion
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Pseudoaneurysm, AVF and haemangioma are rare vascular lesions within parotid gland in adult. The radiologist must be aware of their appearances and should consider them in the differential diagnosis of a parotid mass. High-resolution ultrasound and MRI can establish the diagnosis and the extent of involvement. The main role of conventional angiogram is to delineate the vascular anatomy for planning surgical or endovascular treatment.
Received for publication July 8, 2003.
Revision received September 1, 2003.
Accepted for publication October 2, 2003.
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References
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|---|
- Som PM, Brandwein M. Salivary glands: tumors and tumorlike conditions. In: Som PM, Curtin HD, editors. Head and neck imaging (3rd edn). St Louis, MO: Mosby, 1996:877–914.
- Goldstone J. Aneurysms of the extracranial artery. In: Rutherford RB, editor. Vascular surgery (3rd edn). Philadelphia: WB Saunders, 1989:1600–9.
- Bartoli JM, Triglia JM, Farnarier P, et al. Embolization of an intraparotid false aneurysm of the external carotid artery. Cardiovasc Intervent Radiol 1991;14:173–4.[Medline]
- Lewis R, Lampe H. An aneurysm of the external carotid artery presenting as a parotid mass. J Otolaryngol 1993;22:413–4.[Medline]
- Rhee CS, Jinn TH, Jung HW, Sung MW, Kim KH, Min YG. Traumatic pseudoaneurysm of the external carotid artery with parotid mass and delayed facial nerve palsy. Otolarygol Head Neck Surg 1999;121:158–60.[CrossRef]
- Uguz MZ, Onal K, Oncel S, et al. Giant external carotid artery pseudoaneurysm presenting as a parotid mass. Otolaryngol Head Neck Surg 2000;122:307–9.[CrossRef][Medline]
- Buckspan RJ, Rees RS. Aneurysm of the superficial temporal artery presenting as a parotid mass. Plast Reconstr Surg 1986;78:515–7.[CrossRef][Medline]
- Pochaczevsky R, Richter RM. Traumatic arteriovenous aneurysm of the superficial temporal artery. J Can Assoc Radiol 1970;21:108–9.[Medline]
- Braun IF, Battey PM, Fulenwider JT, et al. Transcatheter carotid occlusion: an alternative to the surgical treatment of cervical carotid aneurysms. J Vasc Surg 1986;4:299–302.[CrossRef][Medline]
- Halbach VV, Higashida RT, Hieshima GB, Hardin CW. Arteriovenous fistula of the internal maxillary artery: treatment with transarterial embolization. Radiology 1988;168:443–5.[Abstract/Free Full Text]
- Gabrielsen TO, Deveikis JP, Introcaso JH, Coran AG. Congenital arteriovenous fistulas supplied by a single branch of the maxillary artery. AJNR Am J Neuroradiol 1994;15:653–7.[Abstract]
- Robertson JS, Wiegand DA, Schaitkin BM. Life-threatening hemangioma arising from the parotid gland. Otolaryngol Head Neck Surg 1991;104:858–62.[Medline]
- Mantravadi J, Roth LM, Kafrawy AH. Vascular neoplasms of the parotid gland. Oral Surg Oral Med Oral Pathol 1993;75:70–5.[CrossRef][Medline]
- Yang WT, Ahuja AT, Metreweli C. Sonographic features of head and neck hemangiomas and vascular malformations: review of 23 patients. J Ultrasound Med 1997;16:39–44.[Abstract]
- Baker LL, Dillon WP, Hieshima GB, Dowd CF, Frieden IJ. Hemangiomas and vascular malformations of the head and neck: MR characterization. AJNR Am J Neuroradiol 1993;14:307–14.[Abstract]
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Abstract
Introduction
