Lymphozele des Ductus thoracicus

Lymphoceles of the thoracic duct, also known as thoracic duct cysts, are lymph-filled collections/dilatations that can arise from any portion of the thoracic duct.

The clinical significance of a thoracic duct cyst lies in its misidentification as a pathological lesion at radiological assessment, which can ultimately lead to inappropriate management.

Clinical presentation

They are usually asymptomatic or less commonly may present as a left supraclavicular fossa mass.

Pathology

The thoracic duct is the main collecting vessel of the lymphatic system. It drains three-quarters of the lymph in the body into the venous bloodstream. The abdominal confluence of lymph trunks gives rise to the caudal origin of the thoracic duct. The abdominal confluence, or the true cisterna chyli when present, extends from the caudal beginning of the thoracic duct to the right of the first and second lumbar vertebrae, lying immediately to the right of the abdominal aorta. The thoracic duct terminates by descending anterior to the first part of the subclavian artery and draining into the junction of the left subclavian vein and the internal jugular vein.

Numerous theories have been suggested to explain the etiology of lymphocele of the terminal thoracic duct. Both congenital weakness in the thoracic duct wall and acquired degenerative process from inflammation have been proposed as causative mechanisms. Trauma has also been suggested as the underlying etiology.

Radiographic features

The dilated thoracic duct will appear as a non-enhancing, tubular/multicystic, multi-compartmental, water density structure starting caudally from the level of the renal hila in the abdomen extending cranially towards the mediastinum till its insertion with areas of more focal dilatation mounting to cyst formation with attenuation slightly lower than the arteries and veins in attenuation .

Treatment and prognosis

Conservative management is generally advocated for lymphoceles of the thoracic duct .

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