British Journal of Radiology (2006) 79, 295-297
© 2006 British Institute of Radiology
doi: 10.1259/bjr/74329476
Diagnosing a parotid lump: fine needle aspiration cytology or core biopsy?
D C Howlett, MRCP(UK), FRCR
Department of Radiology, Eastbourne District General Hospital, Kings Drive, Eastbourne, East Sussex BN21 2UD, UK
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Abstract
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Fine needle aspiration cytology (FNAC) has been widely adopted for the cytological diagnosis of parotid lumps. FNAC does have drawbacks, even under optimum conditions and may be associated with poor levels of diagnostic accuracy, particularly outside the specialized clinic environment. Ultrasound-guided core biopsy (USCB) is a relatively recently described technique in the parotid gland which has been well tolerated and has demonstrated a high degree of diagnostic accuracy in several studies. This article discusses the merits and pitfalls of FNAC, together with the technique of USCB and also highlights the potential advantages benefit provided by USCB in parotid diagnosis.
A broad spectrum of pathologies that present with parotid swelling and extraglandular masses can also mimic parotid lesions clinically. It is frequently difficult on clinical grounds alone to distinguish between neoplastic and non-neoplastic causes for a parotid mass and also to reliably differentiate between benign and malignant neoplasms. If an accurate pre-operative diagnosis can be achieved using a combination of imaging and cytology or histology, then many non-neoplastic lesions will not require excision. Surgery may also be avoided for certain parotid neoplasms in the elderly or unfit, e.g. Warthin's tumour. To ensure that surgery is indicated and to allow appropriate operative planning and patient consent an accurate pre-operative diagnosis is essential.
Following initial demonstration and characterization of a parotid lesion with imaging, usually ultrasound or MRI, needle biopsy is used to confirm its nature if required. Following the demise of open biopsy due to high rates of tumour seeding [1] fine-needle aspiration cytology (FNAC) has become an established technique. FNAC is most commonly performed blindly in the outpatient clinic and has a number of advantages – it is quick, safe and accurate in the hands of a skilled practitioner and high levels of diagnostic accuracy have been quoted [2–4]. This process may occur within a specialized clinic and diagnostic accuracy can be improved using ultrasound-guidance and an on-site cytologist [5]. Clinics may also be cytologist-led, although this may necessitate multiple aspirations and there is currently a severe shortage of cytology staff available with the necessary expertise, making it difficult to offer this facility outside larger centres.
In the absence of ultrasound-guidance, or an on-site cytologist the diagnostic accuracy of FNAC often falls off dramatically. A recent study reported a sensitivity of only 38% in distinguishing benign from malignant disease using blind FNAC [6].
There are also well-recognized pitfalls of FNAC even in experienced hands – particular difficulties may occur in the cytological diagnosis of pleomorphic adenoma [7, 8], Warthin's tumour [9] and lymphoma [10]. Indeed the diagnosis of lymphoma with FNAC is not generally considered definitive, with FNAC often acting solely as a guide for the need for surgical biopsy if lymphoid proliferation is present cytologically [11]. There are specialized ancillary cytological techniques, e.g. flow cytometry and in situ hybridization, which are used to improve the diagnosis of lymphoid proliferation but these are not widely available outside larger centres. The cytological diagnosis of parotid involvement by systemic disease, e.g. sarcoidosis and Sjögren's syndrome may be difficult and it is also not possible to accurately grade or type malignant tumours or lymphomas or to distinguish in situ from invasive disease with FNAC. FNAC has a low predictive value for benign non-neoplastic lesions [3] and similarly there is a low negative predictive value if a negative FNAC result is obtained [4]. As a consequence of the diagnostic difficulties that may arise with FNAC there is a high incidence of surgical biopsy with subsequent delays in referral to the appropriate clinical team.
Performing ultrasound-guided core biopsy (USCB) using a spring-loaded biopsy device does provide a recently described alternative to parotid FNAC. Core biopsy possesses an inherent advantage over FNAC in that it provides a sample of tissue for immunohistochemical analysis. This allows typing and grading of carcinomas and lymphomas and also improved differentiation of reactive nodal hyperplasia from lymphoma. A core of tissue can also be used to evaluate parotid involvement by systemic disease. An on-site cytologist is not required and USCB can be combined with an initial diagnostic ultrasound, allowing lesion characterization and compartmentalization into superficial or deep lobe.
In two series of patients with parotid masses USCB has shown promising results with diagnostic samples obtained in all patients and reported accuracies of 100% [12] and 97% [13] when comparing core biopsy with final surgical histology. There were no reported complications of USCB and 26 out of 54 [12] and 22 out of 53 [13] patients avoided surgery as a result of core biopsy.
USCB utilizes a small bore needle (18 G or 20 G) which is introduced through a small skin incision following informed written consent and infiltration with 1% lignocaine local anaesthesia. Using a high-resolution linear-array transducer for guidance, the needle-tip is positioned just adjacent to the lesion, such that following discharge the needle traverses, but does not exit deep to the lesion (Figures 1 and 2
). The use of ultrasound is important as it allows avoidance of adjacent structures during biopsy and also ensures that both the periphery and core of the lesion are sampled, with bypassing of necrotic areas, increasing diagnostic yield [12]. Some biopsy devices can allow the needle throw to be varied (Magnum gun; Bard, Covington, GA – 15–22 mm variable throw), which is useful for smaller or deeper lesions in proximity to the parotid vessels. There are important potential complications of needle biopsy including haemorrhage and facial nerve injury and also tumour seeding in the needle tract. The identification of the intraparotid vessels on ultrasound should allow the main parotid vessels and thereby the adjacent facial nerve to be avoided during biopsy. There are two reports of tumour seeding post needle biopsy [14, 15] although these occurred with large bore needles and this phenomenon is not described using smaller needle sizes. Some surgeons may choose to excise the biopsy tract at the time of operation. USCB is a little more invasive than FNAC in that it requires local anaesthesia and a skin incision. USCB also does not lend itself to the "one-stop" clinic setting due to longer requirements for histological reporting than a cytology aspirate.
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Figure 1. Ultrasound through the tail of the right parotid gland demonstrates a 12 mm pleomorphic adenoma overlying the angle of the mandible (M). The biopsy needle has been placed just anterior to the lesion, using a 15 mm setting on a variable-throw biopsy device.
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Figure 2. The biopsy device has been discharged and the needle can be seen to traverse the mass, sampling periphery and core, but has not exited deep to the lesion.
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In conclusion USCB represents a recently described technique for diagnosing a parotid mass which has potential benefits over FNAC. These advantages may be particularly relevant in the district general hospital setting where ancillary cytological facilities are not routinely available. The use of USCB may help reduce the need for diagnostic surgical biopsy and thereby facilitate referral to the appropriate clinical team.
Received for publication April 21, 2005.
Revision received August 25, 2005.
Accepted for publication October 11, 2005.
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References
|
|---|
- McGuirt WF, McCable BF. Significance of node biopsy before definitive treatment of cervical metastatic carcinoma. Laryngoscope 1978;88:594–7.[Medline]
- Das DK, Petkar MA, Al-Mane NM, et al. The role of fine needle aspiration cytology in the diagnosis of swellings in the salivary gland regions: a study of 712 cases. Med Princ Prac 2004;13:95–106.
- Cohen EG, Patel SG, Lin O, et al. Fine needle aspiration biopsy of salivary gland lesions in a selected patient population. Arch Otolaryngol Head Neck Surg 2004;130:773–8.[Abstract/Free Full Text]
- Zbären P, Schär C, Hotz MA, Loosli H. Value of fine needle aspiration cytology of parotid gland masses. Laryngoscope 2001;111:1989–92.[CrossRef][Medline]
- Robinson IA, Cozens NJ. Does a joint ultrasound – guided cytology clinic optimize the cytological evaluation of head and neck masses? Clin Radiol 1999;54:312–6.[CrossRef][Medline]
- Balakrishnan K, Castling B, McMahan J, Imrie J, Feeley KM, Parker AJ, et al. Fine needle aspiration cytology in the management of parotid mass: a two centre retrospective study. Surgeon 2005;2:67–72.
- Brachtel EF, Pilch BZ, Khettry V, et al. Fine needle aspiration biopsy of a cystic pleomorphic adenoma with extensive adnexa-like differentiation: differential diagnostic pitfall with mucoepidermoid carcinoma. Diagn Cytopathol 2003;28:100–3.[CrossRef][Medline]
- Verma K, Kapila K. Role of fine needle aspiration cytology in the diagnosis of pleomorphic adenoma. Cytopathology 2002;13:121–7.[CrossRef][Medline]
- Parwarni AV, Ali-Sayed Z. Diagnostic accuracy and pitfalls in the fine needle aspiration interpretation of Warthin's tumour. Cancer 2003;99:166–71.[CrossRef][Medline]
- Loggins JP, Urquhart A. Pre-operative distinction of parotid lymphomas. J Am Coll Surg 2004;199:58–61.[Medline]
- Lioe TF, Elliot H, Allen DC, Spence RA. The role of fine needle aspiration cytology (FNAC) in the investigation of superficial lymphadenopathy – uses and limitations of the technique. Cytopathology 1999;10:291–7.[CrossRef][Medline]
- Kesse KW, Manjaly G, Violaris N, Howlett DC. Ultrasound-guided biopsy in the evaluation of focal lesions and diffuse swelling of the parotid gland. Br J Oral Maxillofac Surg 2002;40:384–9.[CrossRef][Medline]
- Yung-Liang W, Siu-Cheung C, Yao-Liang C, et al. Ultrasonography-guided core-needle biopsy of parotid gland masses. Am J Neuroradiol 2004;25:1608–12.[Abstract/Free Full Text]
- Yamaguchi KT, Strong MS, Shapsey SM, Soto E. Seeding of parotid carcinoma along Vim-Silverman needle tract. J Otolaryngol 1979;81:49–52.
- Peacock EE, Byars LT. Management of tumours of the parotid gland. N C Med J 1958;19:1–9.[Medline]
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