Cervical thoracic duct cyst: a conservative resolution
- 1 Oral and Maxillofacial Surgery, Portsmouth Hospitals University NHS Trust, Portsmouth, UK
- 2 University of Bristol Dental Hospital, Bristol, UK
- 3 Department of Radiology, University Hospital Southampton NHS Foundation Trust, Southampton, UK
- 4 OMFS, University Hospital Southampton NHS Foundation Trust, Southampton Hampshire, UK
- Correspondence to Dr Janine Zixuan Quek; janinequek@hotmail.com
Abstract
A woman in her 70s presented with an enlarging, asymptomatic palpable mass in the left supraclavicular fossa. The clinical impression was of a lipoma. Imaging showed a cystic lesion with continuity of a tubular structure leading to the carotid sheath. Cytology was consistent with thoracic duct sampling. A diagnosis of the rare entity of a thoracic duct cyst with supraclavicular extension was made. This was managed conservatively via repeated aspirations which reduced the size of the mass.
Background
Left-sided neck masses present commonly to general medical practitioners, dentists and in head and neck lump clinics. They can be diagnosed as congenital cysts, lymphatic malformations, pseudoaneurysm of the carotid or subclavian artery, and benign or malignant tumours.1 2
Cervical thoracic duct cysts (CTDCs) are rare lesions of the head and neck space, first reported in 1964 by Steinberg et al.3 They are benign with an unclear aetiology. Previous literature theorise that they could be caused by trauma, obstruction of the thoracic duct, congenital weakness or degeneration.1
The gold standard tool for diagnosing CTDCs are high-resolution imaging combined with aspiration technique. The treatment includes observation, low-fat diet, repeated aspirations, external pressure, sclerotherapy, embolisation and surgical intervention. The preferred management of choice to date is surgical excision.1
Case presentation
We present the case of a woman in her 70s with a long history of a slow-growing swelling in the left side of her neck. The mass was asymptomatic. She denied dysphagia, dyspnoea and weight loss but explained it was normal for her to have occasional night sweats.
She had no history of previous neck operations nor blunt trauma in this region. Her medical history included previous breast cancer.
Clinical examination of the neck revealed a soft, rounded, freely mobile lesion in the left supraclavicular fossa that measured 3–4 cm in diameter. It was not tender, and the skin overlying the mass was normal. No palpable neck nodes were observed.
Investigations
An ultrasound scan (USS) of the neck showed a well-defined, thin-walled anechoic cystic structure within the left supraclavicular fossa, at the site of the soft palpable lump. It measured up to 3.3 cm in maximum dimension. There was no soft tissue component or wall vascularity (figure 1A,B).
(A and B) Ultrasound scan showing well-defined 3 cm anechoic cystic structure within the left supraclavicular fossa (SCF) which appears to track towards the venous system.
The fine-needle aspiration (FNA) cytology aspirated clear yellow fluid which was confirmed as thoracic duct sampling. This was done to exclude malignancy given her background of previous ipsilateral breast cancer.
An MRI of her neck with gadolinium and different sequences (T1, T2 fat-sat and short tau inversion recovery) was undertaken. This revealed the cyst was in continuity with a variable calibre fluid-filled tubular structure, deemed to be an ectatic, slightly ectopic, thoracic duct (figure 2A,B).
(A and B) MRI showing axial and coronal T2 sequences confirms a fluid signal cystic/tubular structure in keeping with the distal thoracic duct prior to termination within the venous system.
Differential diagnosis
Clinically, the mass in the left supraclavicular fossa was suspicious of a lipoma, benign cyst or malignant node. As the patient was examined in a one-stop neck lump clinic, an USS and FNA were undertaken subsequently. The USS suggested a cystic nature, and the FNA showed a clear aspirate sample which excludes a carotid or subclavian artery pseudoaneurysm, haematoma, lipoma nor a seroma. The findings were in keeping with a likely diagnosis of a CTDC. The MRI outlined the association of the lesion with a tubular duct-like structure, hence unlikely to be a branchial cleft cyst or a lymphatic malformation. The illustration of its communication with the carotid space via a tract further supports our diagnosis of a CTDC.
Treatment
Due to its small size with no accompanying symptoms in our patient, a conservative approach via repeated aspirations was undertaken given the benign nature of this and the surgical risks involved with interventional treatment including injection with sclerotherapy and surgical excision of the cyst.
Outcome and follow-up
An initial enlargement of the thoracic duct cyst accompanied by mild discomfort was reported following initial aspiration.
After a subsequent aspiration, this gradually decreased in size with resolution of her symptoms spontaneously. As shrinkage of the thoracic duct cyst with no reported symptoms was observed, no further intervention was carried out, and the patient is under regular observation every 3–6 months.
Discussion
Thoracic duct cysts contain lymph and can present anywhere along the thoracic duct from its origin at the cisterna chyli in the abdomen to its termination at the junction of the internal jugular and subclavian vein.4 Rare but benign lesions, they usually present either cervically in the neck or in the mediastinum. The thoracic duct serves as the main lymphatic channel carrying lymph from the body. It drains into the venous system at the junction where the left internal jugular and subclavian veins meet, accounting for incidences of CTDCs presenting at the left supraclavicular fossa. Our following discussion will be on CTDCs.
Aetiology for these lesions is still unclear. Proposed explanations could be congenital weakness within the thoracic duct wall, acquired inflammation, degeneration or trauma to the duct wall, for example, as a surgical complication. Thoracic duct injury occurs approximately in 1%–6% following a neck dissection.5 They commonly present as a mass in the supraclavicular fossa as soft, fluctuant and mobile. This can be accompanied by symptoms which include dyspnoea, dysphagia and hoarse voice because of pressure of the mass on closely associated structures.6
Fluid aspirated from the cyst appears milky or pale yellow depending on its proportion of protein and triglycerides. Kadkhodayan et al 6 revealed that lymph from the upper abdomen consists of a milky appearance in comparison to a pale yellow appearance of lymph from the retroperitoneum and pelvis.
Imaging modalities used in combination like USS, ultrasound-guided FNA, MRI and CT are useful diagnostic tools. They allow preoperative assessment of its size, anatomical location, boundary and relationship with surrounding structures. Imaging of CTDC commonly presents as well circumscribed, unilocular and oval.5 T2-weighted MRIs of CTDC show increased intensity due to its high triglyceride and protein content, and T1-weighted MRIs will show decreased intensity. Gadolinium enhances delineation of the lesion borders and allows for lymph channels to be distinguished from anatomical boundaries of veins.7 8
A high suspicion for CTDC should be acknowledged if the fluid contents show high lymphocytes, triglycerides and chylomicrons (fat content 0.4%–4%).7 9 Lymphoangiography was previously deemed gold standard for imaging of the thoracic duct. However, this is no longer indicated and is now replaced by MRI and CT due to its superior resolution.9
Due to the rarity of such lesions, there is limited evidence and literature on its management. Conservative and surgical approaches have been employed. Available literature advocated that management of CTDC is dependent on symptoms, size of lesion and its risk of rupture.8 9
Percutaneous sclerotherapy has been proposed whereby a solution is injected directly into the lesion under sonography guidance to cause the cyst to collapse and then eliminated. Successful resolutions of CTDC have been reported with this method using glacial acetic acid, povidone iodine, OK-432 and ethanol.6 However, further studies are required to evaluate its long-term effectiveness.
Surgical removal of CTDC including ligation of connecting lymph channels has also been performed. This comes with a potential risk of chyle leak, chyle fistula formation and infection,4 which may necessitate a further surgical procedure to repair. Preoperative high-fat intake has been advocated to allow for improved visualisation and identification of the cyst and its associated branches intraoperatively.1
Both sclerotherapy and surgery in the supraclavicular region involve risks of damage to vital structures such as vagus nerve, accessory nerve, phrenic nerve, recurrent laryngeal nerve, carotid artery, thyrocervical trunk, subclavian artery and its corresponding veins.1 A novel method of side-to-side venous anastomosis of the internal jugular vein with the cyst has been reported, which showed cyst decompression and resolution of the neck mass.9
Conservative approaches to CTDC have been reported for asymptomatic patients which include monitoring, low-fat or fat-free diet, compression and repeated aspirations.1 One case report of a patient managed conservatively showed resolution of this after 25 years.9
Our case report supports a conservative approach to these rare entities which contributes to the limited existing literature on management of such lesions. However, active observation should be undertaken with appropriate imaging if there are any new or exacerbation of symptoms which may then indicate surgical intervention.
The report also promotes awareness among general medical practitioners, dentists, and head and neck surgeons to recognise this uncommon abnormality as part of their differential diagnoses for lumps in the neck.
Learning points
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Left neck lumps are a common presentation to general medical practitioners, general dentists, and in head and neck lump clinics.
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There is a variety of differential diagnoses.
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One must be aware of the thoracic duct cyst and its management so that the patients can be reassured and managed appropriately.
Ethics statements
Patient consent for publication
Footnotes
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Contributors AA contributed to the acquisition of data. AA and JZQ were responsible for drafting of the manuscript and literature review. Critical revision of the manuscript and final approval of the version to be published were completed by BS, AA and JZQ. BS provided care for the patient. SB made substantial contributions in reporting of and interpretation of special investigations.
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Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
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Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.
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Competing interests None declared.
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Provenance and peer review Not commissioned; externally peer reviewed.
- © BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.
References
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