Abstract
Introduction/Objectives:
Neck lumps are a common presentation to primary care services. The aetiology of posterior neck lumps is poorly explored in the literature, and therefore remain a concern to patients and clinicians. This often results in an urgent referral for ultrasound assessment. The authors of this study sought to evaluate the aetiology of posterior neck lumps from a radiological perspective, to assess whether ultrasound can be used as a useful adjunct, rather than a first-line urgent investigation.
Methods:
A retrospective case series was carried out, examining all primary care referred ultrasound studies for assessment of posterior neck lumps, performed at a single institution in Essex, United Kingdom, over a period of over 10 years dating between 2nd February 2012 to 8th November 2022. Data was collected on: patient age at the time of study, patient sex, whether the lump was single or multiple as palpated and documented by the primary care physician, size of the lump to the nearest 0.5 cm as documented on ultrasound using the longest dimension, sonographic diagnosis and any follow up imaging (not limited to ultrasound).
Results:
A total of 623 neck ultrasounds were performed on 615 adults. Of the overall radiological diagnoses made from the 623 scans, 555 (89.09%) scans were benign, 63 (10.11%) scans had no lump found on sonography, and 3 (0.48%) scans showed malignancy. In the remaining 2 (0.32%) scans, the lump was deemed indeterminate. The most common aetiologies for benign lumps were due to: normal lymph nodes (n = 263; 42.21%), lipomas (n = 152; 24.39%), and benign dermal cysts (n = 105; 16.85%). All 3 malignant cases had co-existing anterior and posterior neck lumps.
Conclusions:
Given that the overwhelming majority of posterior neck lumps in our study had benign findings, we propose that patients with solitary or even multiple posterior neck lumps alone, regardless of size can either be investigated routinely or can be reassured depending on other clinical examination characteristics. Patients who have the presence of co-existing anterior and posterior neck palpable neck lumps justifies urgent or 2-week wait radiological investigation.
Keywords
Introduction
Neck lumps are a common presentation to primary care services. The different anatomical areas of the neck (anterior, lateral, and posterior) each constitute an array of underlying pathologies, consisting of both benign and malignant diagnoses. 1 Whilst anterior and lateral neck lump aetiologies have been well-documented, posterior neck lumps have been less explored and commented on in the literature, leaving malignancy a cause for concern to both patients and primary care referrers. In the United Kingdom, presentation of neck lumps to primary care services are commonly referred for ultrasound imaging evaluation as a first line investigation, 2 under a 2-week wait pathway, to assess for malignancy. Ultrasound imaging can be used to confirm the nature of the posterior neck lump as well as provide information regarding the position and size of the lump. However, previous small studies have suggested low rates of malignancy for posterior neck lumps. 1 A recent surgical case series of post-operative histology even demonstrated that all posterior neck lumps were benign in nature, however the study contained small patient numbers. 1 We sought to evaluate the aetiology of posterior neck lumps from a radiological perspective, on a larger sample of patients, to assess whether ultrasound can be used as a useful adjunct, rather than a first-line urgent investigation. We also sought to identify clinical characteristics which may indicate a malignant aetiology, necessitating more urgent specialist review on the 2-week wait pathway.
Methods
A retrospective case series was conducted, examining all primary care referred ultrasound studies for assessment of posterior neck lumps, performed at a single institution in Essex, United Kingdom, over a period of over 10 years dating between 2nd February 2012 to 8th November 2022. Additionally, all sonographic studies on the picture archiving and communication system (PACS) under the term neck and soft tissue using the key word “posterior” was searched to identify examinations for posterior neck lumps. Our definition of the location of a posterior neck lump is as defined by previous author: 1 posterior to the anterior margin of the trapezius, above the shoulder, below the occiput and including the post-auricular space. Our patient selection included adult patients from primary care referrals only. Paediatric patients under the age of 18 and other subspecialty inpatient requests were not included. Lesions were excluded if they were masses on the: scalp, shoulder, upper back, parotid, supraclavicular area, or arising from the skin.
We collected data on: patient age at the time of study, patient sex, whether the lump was single or multiple as palpated and documented by the primary care physician, size of the lump to the nearest 0.5 cm as documented on ultrasound using the longest dimension, sonographic diagnosis and any follow up imaging (not limited to ultrasound). Where lesions were indeterminate or lost to follow-up we reviewed the patient’s medical notes for further medical consultations and diagnosis. Approval for this study was granted by the HRA and Health and Care Research Wales (HCRW) (reference #334843). Given the retrospective nature of the study, and anonymised use of existing patient data, this study was deemed not to require ethical approval.
Results
A total of 623 neck ultrasounds were performed on 615 adults. During the study period, there were 8 patients who were scanned twice, resulting in the 623 ultrasound studies from 615 individual patients. The cohort consisted of 349 (56.02%) female patients, and 274 (44.98%) male patients. The age range was from 18 to 93 years old, and a mean age of 46 years old at the time of ultrasound. Table 1 shows the number of ultrasound scans per age group.
A Table Outlining the Number of Ultrasound Scans Per Age Group (n = 623).
On physical examination, 569 (91.33%) of patients had a single palpable lump, and the remaining 54 (8.67%) of patients had multiple palpable lumps. Of the 54 patients with multiple palpable lumps, 31 (57.41%) had multiple posterior neck lumps only, whilst 21 (38.89%) had both co-existing anterior and posterior neck lumps, and 2 (3.70%) had no physical lump found on sonography.
Of the overall radiological diagnoses made from the 623 scans, 555 (89.09%) scans were benign, 63 (10.11%) scans had no lump found on sonography, and 3 (0.48%) scans showed malignancy. In the remaining 2 (0.32%) scans, the lump was deemed indeterminate.
The most common aetiologies for benign lumps were due to: normal lymph nodes (n = 263; 42.21%), lipomas (n = 152; 24.39%) and benign dermal cysts (n = 105; 16.85%). The full range of radiological diagnoses are listed in Table 2 below.
A Table Outlining the Range of Radiological Diagnoses (n = 623).
All 3 patients with radiologically malignant posterior neck lumps were found to have pathologically enlarged hypoechoic masses and the eventual histological diagnoses of lymphoproliferative disease was made in these 3 cases. All of these 3 patients had bilateral multiple anterior and posterior palpable neck lumps co-existing. Two of these malignant cases were of chronic lymphocytic leukaemia/small cell lymphoma (CLL/SLL), and 1 case of mantle cell lymphoma. There were no cases of carcinoma or sarcoma found. The patients were at ages 56, 66, and 71 years old and were all male. The size of the posterior neck lumps in these patients were between 1 and 4 cm (Table 3).
A Table Outlining Key Features of Cases of Malignant Posterior Neck Lumps (n = 3).
Of the 2 indeterminate scans, 1 patient was contacted 9 years after the initial scan and it was reported there was no change to the soft mobile lump, and therefore this lump was considered to be benign. The second patient with an indeterminate lump was contacted 2 years after the initial scan and the lump was no longer palpable to the patient and thus also presumed to be benign.
The 8 patients who had repeat ultrasound studies were all for the same initial presenting lump. The time interval between the first and second scans ranged between 3 months to 4 years. In each case, none had a change in the radiological diagnosis (1 cyst, 3 lipomas, and 4 benign-appearing lymph nodes) and none progressed to any malignancy.
All patients with single and/or multiple posterior neck lumps were found to have a benign radiological diagnosis. The size of the neck lump was measured as the longest sonographic dimension and ranged from 0 cm (no lump found sonographically) to 15 cm.
The 31 patients presenting with clinically palpable multiple posterior neck lumps all had benign radiological diagnoses, which included: 2 benign dermal cysts, 3 lipomas, and 26 multiple normal lymph nodes. Of the 21 patients presenting with clinically palpable co-existing multiple anterior and posterior neck lumps: 3 had malignant lesions as described above, and the remaining 18 all had sonographically normal lymph nodes.
One hundred and fifteen patients had a lump 3 cm or above, of which: 10 were benign cysts, 8 were fatty humps, 2 were malignant (lymphoproliferative), 1 was a cystic hygroma, 1 was an intramuscular haematoma, 1 was non-specific soft tissue thickening, and the remaining 92 were lipomas. None showed features of liposarcoma both at the time of the examination and on follow up.
There were 121 patients who had lumps between 1 and 3 cm. From these: 37 were benign cysts, 27 were benign lymph nodes, and the remaining 57 were benign lipomas or benign lesions. There were 307 patients who had lumps 1 cm or less: 1 patient had malignant lymphoproliferative aetiology, 236 were benign lymph nodes, 58 were cysts, and the remaining 12 had benign causes.
Discussion
The results from our case series are in line with previous reports, that the overwhelming majority of posterior neck lumps are benign and the most common lesions are sonographically normal lymph nodes, lipomas or cysts.
Out of 623 scans, there were only 3 instances of malignant posterior neck lumps and these were all histologically confirmed to represent lymphoproliferative disease. Interestingly, all 3 of these malignant posterior neck lumps had co-existing palpable anterior and posterior neck lumps. There were no instances of malignancy found in patients with single or multiple posterior neck lumps only. Therefore, the presence of co-existing palpable anterior and posterior neck lumps appears to be a possible risk factor for malignancy.
Clinical practice guidelines by Pynnonen et al. and National Institute for Health and Care Excellence (NICE) guidelines provide in-depth information on what components are required for a detailed assessment of a patient presenting with neck lump(s).2-3 It is advised to ask patients about the site, onset, size and growth of any neck lumps. Several red flag symptoms, signs, and risk factors, which indicate a concern for malignancy, should be assessed for and are listed in Figure 1. This list is not exhaustive and other site-specific red flag symptoms and risk factors should be considered.
Clinically, our findings suggest that the presence of co-existing anterior and posterior neck lumps also justifies urgent or 2-week wait radiological investigation. However, patients should not automatically be referred for a staging CT neck, chest, abdomen, and pelvis as this would expose a significant number of patients to radiation in whom would not require it. From our results, only 3 out of 21 patients with multiple anterior/posterior neck lumps had malignant neck masses. Therefore, a first-line CT referral would have resulted in unnecessary radiation exposure for the remaining 18 out of 21 patients (85%). Instead, we recommend ultrasound to remain a first-line investigation, which is already a common practice in the United Kingdom.
Our data is supportive of either routine ultrasound investigation, or clinical reassurance if appropriate, rather than urgent or 2-week wait, for patients presenting with solitary or multiple posterior neck lumps of any size, in the absence of red flag symptoms, signs, or risk factors.
We found that lumps larger than 3 cm were lipid in aetiology whether a lipoma or fatty neck hump. This is in line with a previous study by Moss et al. in which they found 79% of surgical operated posterior neck masses were lipomas. 1 In their dataset of 28 patients the average largest dimension of posterior neck lump was 5 cm. Lumps smaller than 3 cm were more often cysts or normal lymph nodes or other less common benign causes listed above.
In line with the radiological literature, size on its own cannot be used as a discriminator between benign and malignant lesions given the 3 instances of lymphoproliferative disease found in our study were 1, 3, and 4 cm in size. This reinforces the notion that sonographic characteristics of a soft tissue lump such as shape, margins and echotexture are more specific indicators rather than size.
Although in our data set we did not find any patient with a malignant single posterior neck lump, there are isolated case reports in the literature of sarcomas presenting as a large lesion in this manner. The most common subtype of sarcoma found were leiomyosarcoma (n = 3), followed by 1 case each of synovial sarcoma, fibrosarcoma, liposarcoma, and Ewing’s sarcoma. The size of the sarcomas described in these case reports were all over 4 cm and pain was only a feature in 2 out of the 7 cases.4 -10 This suggests that the presence of an isolated posterior neck lump cannot be used to completely exclude a malignant lesion, albeit rare and limited to a handful of case reports.
We recognise limitations to our study which include a shorter follow-up time for patients who had a more recent ultrasound as compared to those who had their scan earlier in the study period. We also appreciate patients may have sought medical attention elsewhere, however our trust forms the largest hospital group with the county of Essex and any reattendance at another site within the same county would have been displayed on our PACS system. We did not include those patients referred for sonographic imaging from ear nose throat (ENT) or other relevant specialties as these patients would have co-existing red flag symptoms (for example epistaxis or dysphagia) which would have mandated endoscopic and cross-sectional work up for a head and neck oncological primary. We do not have a sufficiently large enough patient population to produce statistical sensitivities and specificities given only 3 cases of malignant neck lumps were found in the total patient group of 623. Nevertheless, our findings can be beneficial to general practitioners and primary care referrers when deciding urgency of investigation, guiding examination technique and referral for specialist work up, and subsequently reducing the utilisation of radiological services where clinical findings should suffice.
Conclusion
Our case series performed over a 10-year period on 623 ultrasound scans of posterior neck lumps show the overwhelming majority are benign, with only 3 cases of malignancy. Furthermore, all 3 malignant cases were lymphoproliferative in origin, and had the presence of co-existing anterior and posterior neck lumps.
We propose that patients with solitary or even multiple posterior neck lumps alone, regardless of size, and in the absence of red flags, can either be investigated routinely or can be clinically reassured depending on other clinical examination characteristics.
We propose that the presence of co-existing anterior and posterior neck lumps is a risk factor for malignancy, and therefore patients presenting with this, or with other red flags, justifies urgent or 2-week wait radiological investigation.
Footnotes
Author contributions
A.S. and N.C. conceived and designed the project. A.S. collected the data. A.S. performed the analysis. A.S. wrote the paper.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Research Ethics and Patient Consent
Approval for this study was granted by the HRA and Health and Care Research Wales (HCRW) (reference #334843). This study was deemed not to require ethical approval, given the retrospective nature of the study and anonymised use of existing patient data.
