Images in vascular medicine: Recurrent swelling of the left supraclavicular fossa

A 33-year-old woman presented with a painless swelling in the left supraclavicular groove extending to the side of the neck. She reported that the swelling had occurred several times previously over the course of 3 years in the same location and had always regressed spontaneously within 5 days. An inciting event preceding the episodes was not apparent. The swelling was accompanied by diffuse abdominal and flank tenderness, fullness, and flatulence. The patient noted an increase in waist circumference and a weight gain of 1 2 kg. Other symptoms were absent, such as constitutional complaints, dyspnea, loss of appetite, nausea and vomiting, change in bowel habits, or peripheral edema. The medical history was otherwise unremarkable, except for allergic reactions against usual substances (house dust, pollen). The physical examination revealed a marked diffuse swelling, as shown in Panel A, without skin erythema or urticaria. A firm, painless nodule of approximately 3 cm was palpable dorsal to the sternocleidomastoid muscle. Diffuse abdominal tenderness could be elicited by palpation, but there were normal peristaltic sounds and no rigidity of the abdominal wall. Using duplex ultrasound, a cystic tubular lesion of 30 14 17 mm could be demonstrated in the subcutaneous tissue of the left supraclavicular groove, extending medially from the internal jugular vein to the subclavian vein and the clavicle laterally (Panels B and C). There was some solid material adherent to the cyst walls with low echogenicity, and no flow was detected in the fluid-filled areas. Sonographic examination of the abdomen revealed no pathological findings; in particular, ascites, pleural effusions, and lymphadenopathy could be ruled out. Contrastenhanced magnetic resonance tomography was performed as an additional imaging modality (Panel C; T2 and haste sequence). The cervical soft tissue surrounding the cyst appeared infiltrated with edematous fluid. The thoracic duct could be identified as a tubular structure in the mediastinum with a diameter of no more than 3 mm and draining into the cyst. To establish the diagnosis, the cyst was punctured under sonographic guidance. The aspirated fluid had a cloudy, milky appearance and contained 20 400 cells per ml with almost 100% mature lymphocytes. The triglycerides were 1579 mg=dl, cholesterol 80 mg=dl, total protein 4.5 g=dl, and albumin 3.6 g=dl. This composition is unique for chylous fluid and proves the diagnoses of a thoracic duct cyst in this case. A control sonographic examination the next day revealed that the cystic lesion was no longer visible. Cystic dilatations of the thoracic duct have been described in abdominal, mediastinal, and cervical locations, with almost half of the patients being asymptomatic. Most of the cysts are related to surgical or traumatic lesions, for example during radical neck dissection or thoracic surgery. Spontaneous supraclavicular thoracic duct cysts are very rare and should be included in the differential diagnosis of lateral cervical masses because inadvertent damage to the thoracic duct can result in chylous fistula or chylothorax. Regarding pathogenesis, hypotheses include congenital weakness of the vessel wall as well as acquired degenerative and inflammatory processes. Surgical excision of cervical thoracic duct cysts is only indicated if the cyst is causing symptoms, is cosmetically unpleasant, or if rupture may be anticipated leading to chylothorax. Resection can be performed with good results if care is taken to ligate all lymphatic vessels connected to the cyst based on knowledge of the highly variable thoracic duct anatomy. Options for conservative management include repeated percutaneous aspiration and a low-fat diet supplemented with mediumchain triglycerides. Departments of Angiology and Radiology, Medical Center of the University of Munich, Germany