Journal of Cancer Research and Therapeutics

: 2013  |  Volume : 9  |  Issue : 1  |  Page : 148--150

Detection of atypical metastases in recurrent adenoid cystic carcinoma of parotid gland

Anshu Tewari, Subramanyam Padma, Palaniswamy Shanmuga Sundaram 
 Department of Nuclear Medicine & PETCT, Amrita Institute of Medical Sciences, Cochin, Kerala, India

Correspondence Address:
Anshu Tewari
Department of Nuclear Medicine & PETCT, Amrita Institute of Medical Sciences, Cochin, Kerala


We report a known case of adenoid cystic carcinoma of right parotid gland in a 36-year-old Indian male, diagnosed 5 years ago for which he underwent surgery followed by radiotherapy. Now the patient has presented to the surgical oncologist with a mass near angle of right jaw. Computed tomography (CT) performed elsewhere was reported negative for local recurrence. Subsequently, 18 F Fluorodeoxyglucose positron emission tomography-CT (FDG PET-CT) demonstrated local recurrence in right parotid bed. Surprisingly, metabolically active metastatic skeletal deposits were also identified, thus the disease was upstaged and management was changed. Trucut biopsy from left iliac bone lesion confirmed metastases from adenoid cystic carcinoma. Thus a whole body PET-CT has a significant impact on management of patients with salivary gland malignancies in assessing both local recurrence as well as distant metastases, especially in atypical and unsuspected sites.

How to cite this article:
Tewari A, Padma S, Sundaram PS. Detection of atypical metastases in recurrent adenoid cystic carcinoma of parotid gland.J Can Res Ther 2013;9:148-150

How to cite this URL:
Tewari A, Padma S, Sundaram PS. Detection of atypical metastases in recurrent adenoid cystic carcinoma of parotid gland. J Can Res Ther [serial online] 2013 [cited 2020 Mar 30 ];9:148-150
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Tumors of salivary glands are rare and represent less than 1% of all cancers and approximately 5% of head and neck cancers. Parotid glands, being the largest salivary gland are also the most common site of salivary tumors, accounting for 75% of salivary gland malignancies. Among the salivary neoplasms, adenoid cystic carcinoma also known as cylindroma is very rare and constitutes 1% of major and minor salivary glands malignancies and accounts for only 15% of parotid malignancies. [1]

 Case Report

We report a known case of adenoid cystic carcinoma of right parotid gland in a 36-year-old Indian male, diagnosed 5 years ago for which he underwent total parotidectomy followed by postoperative adjuvant radiotherapy (RT) elsewhere (60 Gy/30 fractions). Now patient has presented to the surgical oncologist with a mass near right angle of jaw. 18 F Fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) was performed on a PET 8 slice CT scanner to assess the present disease status. Eight millicurie of 18 F FDG was injected intravenously in euglycemic status and head to mid thigh imaging was performed an hour later. The whole body PET-CT scan revealed abnormal enhancing lesions with increased FDG uptake in right parotid bed, that is, posterior to mandibular condyle, anterior to external auditory canal and another lesion in digastric groove lying posterior to styloid process (standard uptake value (SUV) max is 5.7 g/ml) consistent with local tumor recurrence and associated infiltration of tumor into facial nerve [Figure 1]. Although clinically only a local recurrence was suspected, PET-CT revealed metabolically active skeletal metastases involving the spine of right scapula and left iliac bone (SUV max 4.1 and 2.6 g/ml, respectively) [Figure 2] and [Figure 3]. Thus PET-CT has upstaged the disease and changed the management. Trucut biopsy from left iliac bone lesion and fine needle aspiration cytology (FNAC) from right parotid bed confirmed the lesions to be metastases from adenoid cystic carcinoma and local recurrence [Figure 4]. Patient underwent completion parotidectomy along with right sural nerve graft and gold weight right upper eye lid repair for ptosis followed by a palliative RT to the scapula and iliac crest with 30-45 Gy in 15 fractions. Three months post therapy PET-CT scan showed partial metabolic response (reduction in SUV) of right parotid, left iliac, and right scapular lesions with no further progression of disease [Figure 5].{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}


Salivary gland tumors are usually benign and by far the most common site is the parotid. Of the parotid gland malignancies, mucoepidermoid carcinoma is the most frequent with an incidence of 21.8%. [1],[2] Other parotid malignancies that are known to occur are adenocarcinoma, squamous cell carcinoma, and adenoid cystic carcinoma in descending order of incidence. [2] 18 F-FDG PET has been shown to be superior to conventional imaging in evaluating patients with head and neck malignancies. [3] In major types of head and neck malignancies like squamous cell carcinoma and lymphomas, FDG PETCT is now used in initial staging, management of recurrent cancers, and therapeutic monitoring. [4] According to recent reports, [5] the higher sensitivity and diagnostic accuracy of PET-CT endows it with many advantages over CT alone in managing malignancies around the salivary gland, especially in high-grade types. Enhanced glucose metabolism, as determined by the SUV, is a strong index of tumor grade in several malignancies. [4] A correlation exists between 18 F-FDG uptake and tumor invasiveness. Tumour histologic grade is significantly related to FDG uptake. The tumour is aggressive if SUV is greater than 4.0. High-grade salivary malignancies tend to have higher 18 F-FDG uptake than low- or intermediate-grade salivary tumors. The preoperative diagnosis of salivary gland masses should include fine needle aspiration biopsy (FNAB), CT, or magnetic resonance imaging (MRI) as well as 18 F-FDG PET. In detecting metastatic neck disease, preoperative FDG PET is more sensitive than CT. Main limitation with FDG PET-CT is the fact that low-grade salivary gland malignancies with relatively low FDG uptake may be easily obscured by the normal physiologic FDG uptake of the salivary glands with reported SUV of less than 2.9 g/ml. [5] In addition, FDG uptake may be increased by inflammatory processes, contributing to false-positive results. [5] These errors can be corrected when conventional CT or MRI is combined with FDG PET.

The sensitivity and specificity of CT in detecting extracranial adenoid cystic carcinoma of oral cavity and oropharyngeal tumors with perineural spread are 88% and 89%, respectively. [8],[9] However, false negative results on CT are commonly associated with inherent insensitivity in identifying especially lymph nodal micro metastases (nodes less than 1 mm in size) and skeletal deposits [6],[8] suggesting that CT alone may be insufficient in staging, particularly in patients with high-grade salivary gland malignancies. [9]

Distant metastases from primary malignant parotid tumors are quite rare, [5] lungs being the most common followed by bone and liver. Although literature review reported metastases in context to adenoid cystic carcinoma, acinic cell carcinoma, [5] none of them reported scapular and ilium as site of distant metastases. Only one humeral metastases from parotid adenocarcinoma has been described in a canine. [7] Our case may be the first report of parotid adenoid cystic carcinoma presenting with scapular and iliac bone metastases. These tumors are slow growing with propensity to recur to adjacent structures easily. Recurrence and metastases usually happens years after initial presentation, therefore long-term follow up and constant vigilance is necessary . . On the contrary, this patient presented with local recurrence as well as skeletal metastases in a span of 5 years. FDG PECT-CT has a significant role in diagnosing such atypical and highly unsuspected site of distant metastases in the management of patients with adenoid cystic carcinoma of parotid gland.


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