Talk:Paper - True congenital diverticulum of the trachea in a subject showing also right aortic arch (1929)
TRUE CONGENITAL DIVERTICULUM OF THE TRACHEA IN A SUBJECT SHOWING ALSO RIGHT AORTIC ARCH
By E. P. STIBBE
Dyverricunum of the trachea—sometimes called aerocele—is not an excessively rare condition. Ziegler and Kahlden(1) report a case in 1897 and give a number of references; they discuss at length the causation and pathology of the condition. It would appear that diverticula may be produced as ‘‘pulsion-diverticula” in cases of chronic pulmonary and bronchial disease (Rokitansky (2)); the critical pathological feature is a greater or less destruction of the elastic tissue of the bronchi and trachea, as is known in cases of bronchiectasis. According to Gruber(3) tracheal diverticula are retentioncysts of the large mucous glands in the wall of the trachea, which glands are especially large and numerous in the posterior wall of the tube. According to Stirling (4) the acini of the mucous glands of the trachea lie outside the trachealis muscle, so that their ducts have to pierce that muscle to open into the lumen of the trachea. He emphasises the large size and number of the glands opposite the trachealis muscle and Bland-Sutton(5) points out that tracheal diverticula “invariably occur near the junction of the trachealis muscle with the cornua of the semi- rings of the trachea.”
W. S. Muller (6) gives a full description of. the musculature of the trachea. It appears that the transverse fibres constituting this‘muscle form relatively independent bands. These bands are situated opposite the cartilages, being attached at their extremities to the free ends of the incomplete cartilaginous rings. Between the adjacent bands are relatively amuscular areas—so that the position of the orifice of a diverticulum at a level between two rings would correspond to a weak area in the musculature.
All the cases under any of the above headings are due to pathological causes. Most of them are associated with chronic respiratory disease. A most important anatomical feature of these cases is that the opening into the trachea is relatively large (e.g. 2cm. x 1$.cm., Ziegler and Kahlden). The special features of the present case are that the opening into the trachea is pin-point in size, and that the histological appearances are those of normal bronchus—except in the absence of cartilage. It would appear therefore to be a true developmental anomaly.
The subject was an adult female aged 46 years, received from an asylum. Death was reported as due to “heart disease,” with no report of any noteworthy respiratory condition. An enquiry made from the asylum officer with True Congenital Diverticulum of the Trachea 63
respect to this, and also with respect to the existence of any special physical signs—as pulsations—received a negative reply. The subject showed a moderate parenchymatous enlargement of the thyroid gland,-and had a right-sided aortic arch and descending aorta as reported below. No other anomaly or important pathological condition was noted.
The tumour was a large rounded cyst-like body wedged in behind the upper part of the manubrium sterni and immediately above the rather high aortic arch. Its position is indicated by the arrow in fig. 1. The upper pole
of the tumour just touched the lower pole of the rather large right lobe of the thyroid. The position, size and shape, and consistency were such that it resembled a thyroid adenoma; had it been palpable during life—which it probably was not—this would have been the diagnosis. The tumour, however, showed no connection with the thyroid gland. It was, on the contrary, freely . movable and could be “shelled” out from its bed without any dissection. It was then found to have a long thread-like pedicle which was dissected out down to the back of the trachea about one inch above its bifurcation. A very 64 E. P. Stibbe
fine wire was passed along this pedicle and found to enter the back of the trachea by a pin-point opening; the opening showed definite rounded margins when examined with a hand-lens.
Histological examination (fig. 2) shows a number of irregular rounded spaces containing epithelial debris. The spaces are lined by a double-layered epithelium characteristic of the respiratory tract, namely, a basal layer of cuboidal cells, surmounted by a layer of tall columnar cells with long close cilia on their free edge. Beneath the mucous membrane is loose areolar tissue in the meshes of which are numerous lymphoid corpuscles; in places the lymphoid cells are closely packed. Muscular tissue was not observed, and elastic fibres were sparingly scattered through the section. No cartilage was present.
Section of the trachea shows nothing abnormal, but there is perhaps a diminution in the amount of elastic tissue.
The opening into the trachea was inspected from within the trachea. It shows as a tiny white speck in the posterior wall to the right side of the mid-line: it will Fig. 2 just pass a medium-sized pin. Immediately above it are two similar white spots which under a hand-lens are seen to be orifices of muceus glands; there are no external swellings opposite these openings. No histological study was made of the orifice, but the hand-lens was sufficient to show that the tracheal mucosa was continued into the opening—it represented a definite evagination.
The position of the opening was between the levels of two of the cartilaginous rings. ,
This tumour cannot come under the head of any of the types referred to in the introduction. It is not glandular as proved by its histology. It is not a traction diverticulum since it was free from adhesions, and could in fact be dislocated from its bed without any dissection; it can hardly be a pulsion diverticulum with a pin-point opening, and there is no clinical history or post-mortem evidence of important respiratory disease.
The writer believes that the clue to this diverticulum is to be found in the accessory bronchus of Aeby(7). L. Dalla Rosa(8) catalogues eight cases True Congenital Diverticulun of the Trachea 65
of supernumerary bronchus and one case of these corresponds with the present in that the bronchus fails to join the lung. The author calls it a congenital tracheal diverticulum, and believes it to be a rudimentary third stem-bronchus.
These conditions make it reasonable to suppose that we have here an abortive lung bud—a genuine case of Aeby’s supernumerary bronchus. No reason can be found for associating the diverticulum with the abnormal aortic arch described below—except the usual tendency for anomalies to be multiple.
THE AORTIC ARCH OF THE SAME SUBJECT
Right aortic arch without other transposition of viscera is a well-known condition, yet perhaps of sufficient interest to justify the recording of cases as they are observed. The present case is one of the less common varieties— one in which, while the left fourth aortic arch has disappeared, the left dorsal aorta from the level of the fourth arch to the junction of the two dorsal aortae has persisted to form the left subclavian artery. This type of variation is figured by Quain(9) and has been described in the adult by D. G. Reid (10) and in a foetus by Garnier and Villemerdil).
On opening the thorax the arch of the aorta looked normal in direction, but on further investigation it was seen (fig. 1) that
(a) it was longer than usual, rising to the body of the third thoracic vertebra; c »
(b) the left common carotid arose from the ’ . ascending aorta about one inch from its commencement;
(c) the arch turned towards the left for a short distance, and then with a sharp kink turned backwards and downwards across the body of the third thoracic ° vertebra to the fourth, where it diverged to the right; subsequently its course down the right side of the vertebrae was as that of the normal descending aorta on the left.
Branches (fig. 3). The left common carotid
(c) was the first branch as mentioned.
The right common carotid (c’) and subclavian (s’) came off separately at a position on the right side symmetrical with the usual leftside position; there was no innominate artery.
The left subclavian (s) comes off from the point where the arch turns suddenly back prior to taking its turn to the right; but the proximal part of
Anatomy LXIv 5 66 E. P. Stibbe
this subclavian is almost as large as the aorta, and abruptly narrows down to normal subclavian size about three-quarters of an inch from the aortic arch. This origin of the subclavian lies behind the trachea.
The ductus arteriosus (d) connects the junction of the pulmonary arteries to the subclavian just at the point where the latter becomes of normal size.
The right vagus nerve crosses the first part of the right subclavian artery and the right side of the arch; the right recurrent laryngeal nerve hooks round the aortic arch. The left vagus runs down in front of the first part of the subclavian artery, and the left recurrent nerve hooks up behind the ductus arteriosus.
This is one of the less common forms of right aortic arch, but is a wellrecognised variety. It corresponds, for example, precisely and in all its details to the third case of Reid(10) and its embryology is not difficult to decipher. No doubt the left common carotid represents the left branch of the ventral aorta as far as the third left arterial arch. Since this artery is normally formed from the third arch and that part of the ventral aorta between the third and fourth arches, it now includes the part of the ventral aorta which lies between fourth and fifth arches. This included vessel is that which normally forms innominate on the right side. In this case it forms the aortic arch on the right side—hence the absence of innominate. The pouch-like origin of the left subclavian is the distal part of the left dorsal aorta, extending from behind the trachea upwards and to the left to join the subclavian at a point corresponding to the usual origin of that vessel from the fourth arch; the fourth arch itself is missing.
(1) ZrEcLER and KanLpEn (1897). Centralblatt f. allg. Path. u. path. Anatomie, Bd. vim, p. 18. (2) Roxiransxy (1855). Pathologischen Anatomie. Wien. (3) Grouper. Anat. Mem. Berlin, 1879-89. (4) Smrwine, W. (1883). Journ. Anat. and Phys. vol. xvi, p. 204. (5) Buanp-Sutton (1917). Tumours Innocent and Malignant, p. 716. (6) Mutuzr, W. S. (Nov. 1913). Anat. Record, vol. vi, No. 11, p. 373. (7) AxrBy (1880). Bronchialbaum der Sdugethiere und des Menschen. (8) Data Rosa (1889). Wiener klin. Wochenschr. pp. 22-24. (9) Quatn (1844). Ailas of the Arteries. Vol. 1, Pl. VII, fig. 1. (10) Rem, D. G. (1914). Journ. Anat. vol. xiv, p. 174. (11) Garnter and VILLEMER (1910). Bibl. Anat. vol. x1x, p. 286.