AJR 2000; 174:1003-1004
© American Roentgen Ray Society
Esophageal Pseudomass
Extrinsic Compression of the Esophagus Due To a Narrow Thoracic Inlet
Mark J. McClure1,
Peter K. Ellis,
Ian M. G. Kelly and
Martin McGovern
1
All authors: Department of Radiology, Royal Victoria Hospital, Grosvenor Rd.,
Belfast, BT12 6BA, Northern Ireland.
Received June 14, 1999;
accepted after revision September 21, 1999.
Address correspondence to P. K. Ellis.
Introduction
Anarrowed sagittal diameter of the thoracic inlet is a recognized anatomic
variant [1]. We describe a
37-year-old woman with dysphagia in whom a narrowed thoracic inlet caused
extrinsic compression on the esophagus between the trachea and vertebral body,
resulting in a pseudomass appearance. We advocate the use of CT with sagittal
reconstruction to exclude disease and accurately assess the thoracic inlet
diameter.
Case Report
A 37-year-old woman presented with a short history of painful swallowing.
She had been treated for 5 years for ulcerative colitis with mesalazine
(Asacol; SmithKline Beecham, Welwyn Garden City, UK) and prednisolone
(Medrone; Pharmacia & Upjohn, Milton Keynes, UK). A direct esophageal
examination was performed by an otorhinolaryngology specialist; no abnormality
was revealed and a barium swallow was requested. This study showed an apparent
external compression on the upper esophagus from the right side at vertebral
level C6-T2 (Fig. 1A). CT
failed to show a mass lesion but revealed the close proximity of the trachea
to the vertebral bodies at the cervicodorsal junction and the resultant
deviation and compression of the esophagus (Figs.
1B and
1C). The anteroposterior
thoracic inlet measured 3.4 cm.
Subsequently, we identified a second case with similar imaging findings. A
19-year-old man presented with intermittent dysphagia and a subjective feeling
of food sticking at mid-sternal level. On CT no mass lesion was seen and the
sagittal thoracic inlet diameter was 4.1 cm.
Discussion
A narrow thoracic inlet is a rare entity, but it is a recognized normal
variant [1]. The normal
anatomic boundaries of the thoracic inlet
[2] are the manubrium
anteriorly, the first thoracic vertebral body posteriorly, and the first ribs
laterally. The plane of the inlet is tilted downward anteriorly and is higher
on each side medially than laterally. Major normal structures include nerves
(vagus, phrenic, and recurrent laryngeal nerves; sympathetic chain; and
brachial plexus), vessels (subclavian, brachiocephalic, and carotid arteries
and jugular veins), lymphatics (thoracic and right lymphatic ducts), the
trachea, and the esophagus. The normal sagittal thoracic inlet distance
measures a mean of 6.2 cm and ranges from 5.0 to 8.7 cm
[3].
In both cases described, the barium swallow showed extrinsic compression of
the barium-filled esophagus from the right side with displacement to the left
and narrowing of the esophageal lumen. This finding suggests a mass lesion.
The radiologic appearance of the barium swallow in our patients was similar to
that described by Kendall et al.
[4] in 1962. They measured the
thoracic inlet using conventional radiography (lateral thoracic inlet view)
and found an association with the barium findings and a value of 5.3 cm or
less.
Factors that may contribute to this appearance include the shape of the
thoracic cage, the position of the trachea and vascular structures, and the
degree of cervical lordosis. The esophagus tends to be displaced
preferentially to the left by compression between the trachea and the
vertebral body [3].
At the cervicodorsal junction, various conditions could give rise to this
appearance [5,
6]. More commonly, conditions
such as mediastinal and cervical lymphadenopathy, goiter, Pancoast's tumor,
hematoma, abscess, and thoracic osteophytosis are seen. Rare causes include
duplication cyst, branchial cyst, neurogenic tumor, and vascular causes such
as aberrant right subclavian artery. Recently, an indentation of the upper
thoracic esophagus was described as caused by a prominent right inferior
supraazygos recess [7].
Our CT findings (Figs. 1B
and 1C) correlated with those
described in 1996 by Rafeeque et al.
[8], in which the absence of a
mass on CT was associated with a narrow thoracic inlet (<5 cm) and
esophageal position to the left side of the trachea. Rafeeque et al. ascribed
their findings to an esophageal "pseudomass." In both of our
patients, we calculated the anteroposterior diameter of the thoracic inlet by
CT measurement, optimally shown by the CT sagittal reconstruction
(Fig. 1C). This method of
measuring the thoracic inlet has not, to our knowledge, been previously
described and we found this method to be the easiest and most logical way to
measure the minimum distance between the posterior cortex of the manubrium and
the spine. The sagittal reconstruction is important because the plane of the
thoracic inlet is tilted downward anteriorly. Taking the measurement simply
from an axial section could result in geometric error.
In conclusion, a narrow thoracic inlet is a described anatomic variant
[1]. This variant may cause
extrinsic compression of the esophagus at the cervicodorsal junction and may
mimic a mass lesion. CT examination excludes a mass and enables measurement of
the thoracic inlet.
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Introduction
Case Report
