Ultrasound guided wire localisation to aid surgical biopsy of impalpable parotid oncocytoma

Abstract

Ultrasound guided wire localisation (UGWL) is an effective way of helping a surgeon find an impalpable lesion but its use in the head and neck has only recently been described. The authors present an unusual case of bilateral multi-focal parotid oncocytoma, in which UGWL was combined with extracapsular dissection to obtain an impalpable lesion for histological examination following initial equivocal core biopsy.

Ultrasound guided wire localisation (UGWL) is a well recognised procedure in breast surgery as it is an effective way of locating impalpable lesions, including cysts and benign and malignant tumours . Its use in head and neck surgery has been described for locating a range of impalpable lumps including a brachial cyst and a thyroglossal cyst . The technique has not been previously used for locating parotid lesions. The authors present a case of bilateral multi-focal oncocytoma in which initial equivocal core biopsy could not exclude the possibility of malignancy without further histological examination of a larger specimen. Extracapsular dissection was to be used to excise a small superficial lesion. On palpation this lesion could not be distinguished from the main body of tumour so it was decided to use UGWL to locate the lesion and to ensure the adjacent dominant lesion did not have its capsule breached and contents spilt. It also facilitated a conservative surgical technique, as tissue was not damaged unnecessarily to locate the lesion.

Case report

A 77-year-old male presented with a 6-month history of a painless, non-progressive, right parotid swelling. On examination, a palpable, 5 cm by 3 cm, firm, rubbery swelling was noted in relation to the right parotid gland with no significant overlying skin deformity. There was no facial nerve palsy or dysphagia and the left parotid gland appeared normal. There were no palpable neck lymph nodes.

Ultrasound imaging demonstrated multiple circumscribed, hypoechoic lesions within both parotid glands, consistent with likely benign tumour, possibly Warthin’s. Multiple 18 gauge core biopsy samples were taken under ultrasound guidance from the dominant lesion in the right parotid gland, which was noted to extend into the deep lobe. Initial histology gave a provisional diagnosis of oncocytic tumour but malignancy could not be excluded without a larger specimen.

Magnetic resonance imaging (MRI) of the parotid glands was necessary to define the size and position of the tumour accurately. This confirmed multi-focal lesions of similar signal within each gland ( Fig. 1 ). The lesions were consistent with probable benign tumour, and deep lobe involvement on the right was confirmed. To confirm the likely benign diagnosis and to avoid parotidectomy it was decided to excise a superficial preauricular lesion from the right parotid identified on imaging. The lesion to be targeted was impalpable and in close proximity to the large adjacent mass, lying a few millimetres away. UGWL was to be used to locate the lesion accurately to reduce the risk of breaching the capsule of the larger body of tumour. Extracapsular dissection was favoured over superficial parotidectomy owing to the decreased associated morbidity .

Fig. 1
Coronal T1 weighting MRI with an arrow indicated the most superficial low signal right sided lesion. Inferior to this nodule a larger lesion can be seen extending in the deep lobe of the right parotid gland. No lesions of the left parotid are in the field of view here.

Method

The technique used for UGWL was as previously described by B reeze et al . The lesion was identified preoperatively using ultrasound and the surgical plane drawn onto the preauricular skin by the surgeon. A 19 gauge, 50 mm localisation needle was inserted behind the surgical plane, through an incision, under local anaesthetic and was directed into the lesion under ultrasound guidance using a high resolution linear array transducer ( Fig. 2 ). The bevelled tip was positioned centrally in the lesion and the hook wire was deployed from the centre of the needle. The needle was then removed leaving the anchored wire in situ. A cross was drawn onto the skin directly overlying the tip of the wire as a reference to the surgeon. The depth of the wire was recorded in the notes as 10 mm.

Feb 7, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Ultrasound guided wire localisation to aid surgical biopsy of impalpable parotid oncocytoma
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