AN ANOMALY OF THE THORACIC DUCT WITH A BEARING ON THE 

 EMBRYOLOGY OF THE LYMPHATIC SYSTEM. 



By Eliot R. Clark. 



The case which is to be described has an exceptional interest, both because of its rarity 

 and because of the bearing which it has on the still unsettled problem of the mode of develop- 

 ment of the thoracic duct. It occurred in a dissecting-room subject, in a negro female 

 (No. 3408 in the dissecting-room series of the Johns Hopkins Medical School), aged 39 

 years, of slight build, distinctly below the average in height, weighing only 102 pounds, 

 whose death was due to "tuberculosis" (a diagnosis borne out by the condition of the lungs 

 noted in the course of dissection). Thanks are due to Miss Goldman, Mr. Amberson, and 

 Mr. Banks, without whose careful dissection and cooperation the report of this case would 

 not have been possible. 



Attention was first drawn to the lymphatic system by finding, during the dissection 

 of the lower neck and axilla, a number of lymphatic vessels which were unusually distended 

 by a whitish coagulum. One of these vessels, larger than the others, extended down into 

 the axilla, where it received branches from numerous enlarged lymph glands. The duct 

 extended beyond the axillary glands, in the direction of the thoraco-epigastric vein, in the 

 subcutaneous tissue of the lateral body wall. At about the level of the sixth intercostal 

 space the duct was cut across, in separating the fascia at the dividing line between the two 

 dissection fields, before it had been found that there was anything unusual about the 

 lymphatics. At the cut end the diameter was still considerable, and it was remarked at the 

 time that this vessel was very much larger than could be accounted for by the lymph 

 coming from the axillary glands alone. Anteriorly the duct joins the left subclavian vein 

 in the angle formed by this vein with the internal jugular. Near the opening a second, 

 smaller lymph duct was found, joining the subclavian. A search was made before the 

 thorax was opened for the terminal portion of the thoracic duct and a fine vessel was seen 

 in the usual position for the end of the thoracic duct, but was broken during the dissection. 



Somewhat later, Mr. Amberson, dissecting the lower left thoracic and abdominal wall, 

 traced a supposed subcutaneous "vein" from the lateral thoracic region posteriorly over 

 the abdominal wall, and over the ligamentum inguinale (Poupart's) into the superficial 

 fascia of the femoral triangle. To his great surprise he found that ducts led from the 

 inguinal lymph glands into this supposed "vein" — that, instead of a vein, he had been 

 following a greatly enlarged lymph duct. The case now became one of much interest; 

 from the size of the duct it was suspected that it must drain at least a part of the abdominal 

 viscera. Fortunately the thoracic and abdominal viscera had not yet been disturbed, so 

 that it was possible to dissect here the main lymphatics. 



The duct which had been followed along the lateral thoracic and abdominal wall was 

 first studied. (Fig. 2, m. l. d.) It is a substantial vessel, which is duplicated posteriorly 

 and anteriorly by smaller vessels. The middle undivided part consists of a stretch, 10 cm. 

 long, starting from a point 14 cm. from the ligamentum inguinale, where it receives the 

 posterior duplicating vessel. (Fig. 2, p. d. l.) The main duct has a marked widening 

 above the ligamentum inguinale. Below the ligament its diameter is about 2.2 mm., 

 while 3 cm. above the ligament its diameter is approximately 4.0 mm. This diameter 



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