Using our database,
we have selected all the chest CTs performed during the last year (From January to December 2018) and we reviewed over 2600 CTs; we have therefore selected all the reports in which accessory findings were reported and we have studied the images of these exams.
We studied them twice: once focusing on the clinical suspect and once again using a methodic approach to analyze the whole image.
In a large amount of chest CT scans,
at the first look,
we missed several lesions in vascular structures,
soft tissues and upper airways that were then noticed in our second approach.
The most common lesions we found on our second look are described,
showing their radiological features and emphasizing their clinical relevance.
Considering that during the report of a chest CT we focus mainly on parenchyma,
bronchi and lymph nodes,
we found that other thoracic regions may be underestimated during our study.
The main lesions that were missed on our first look,
regarded the following structures: mediastinum (thymus and thyroid),vessels,
bones,
diaphragm,
breast and soft tissues,
muscles,
windpipe,
esophagus.
For each omitted anatomical structure,
we comment on images extracted from our series.
Mediastinum
One of the most frequent accessory findings in our series is represented by the thymic residue.
This condition is frequently found especially in pediatric cases (up to 64%),
while it is rarer in adulthood [1] and can be a cause of diagnostic error and unnecessary anxiety,
and does not normally require therapeutic initiatives,
in isolated cases has been described as possible cause of Horner's syndrome [2] (FIG 1) Another condition that in some cases may go undetected,
and therefore under-diagnosed,
is the thyroid goiter,
a relatively frequent condition,
although there are no accurate statistics in The possibility of finding this type of lesion is strictly correlated with the size of the gland,
which can be considerable,
and of any associated focal lesions.In our case series,
we have found several cases of immersed goiters,
a very small number of cases has not been identified in the first evaluation,
but this accessory finding is still important to report and because it may be home to benign and malignant diseases and also enters differential diagnosis with all the masses of the upper mediastinum (FIG 2,
FIG 3)
Vessels
Vascular malformations represent an unusual finding.
The condition called lusor artery is an uncommon condition,
which may be completely asymptomatic or associated with cough,
gastro-esophageal reflux and dyspnea,
found up to 2.5% in autoptic cases and accounts for 17% of all aortic arch malformations [3].
The term "lusoria" refers to dysphagia "may be called lusoria,
from lusus naturae" (Latin for "freak of nature") that gives rise to it" (FIG 4).
Another vascular malformation not uncommon in TC is represented by the bovine arch; in this type of abnormal vascular we observe the anomalous origin of the anonymous trunk and of the left common carotid directly from the aortic arch: this condition is usually asymptomatic and therefore constitutes an accessory finding that could escape an inadequate analysis (FIG 5).
Windpipe
The trachea is rarely associated with the finding of malformities pathology and in most cases the anomalies are well evident; more limited structural anomalies can go instead quite unnoticed if asymptomatic: it is the case of tracheal diverticulum,
an aerial cyst that develops in paratracheal site with a congenital or acquired character,
often completely asymptomatic or responsible for dysphagia,
odynophagia,
neck pain,
hoarseness,
hemoptysis,
choking,
and recurrent episodes of hiccups [4] (FIG 6).
Tracheomalacia is not uncommon in our experience,
although it is reported at 10% in some cases [5]; characterized by collapse for more than 70% of the expiratory trachea,
it can be acquired or,
very rare,
congenital,
and is often asymptomatic or accompanied by non-specific symptoms such as persistent cough,
breathing difficulties and recurrent infections.
The clinical importance in the detection of this lesion is correlated with the possibility of explaining some clinical features of the patient in light of the tracheomalacia relief (FIG 7).
Esophagus
In our series we have noted that achalasia,
in a CT examination,
could be misunderstood; the most relevant datum is represented by dilatation of the esophagus which presents itself with thin walls; however,
CT is not the most suitable method to study this pathology (FIG 8).
Soft tissues
In addition to the evaluation of the mediastinum,
the analytical method for the correct interpretation of a CT scan of the thorax cannot disregard the careful evaluation of the bony structures and soft tissues.
In these structures it is possible to appreciate both the presence of benign conditions,
such as bone fractures ever in consolidation,
or malignant ones,
such as breast neoplasia.
From our series we report cases of vertebral fractures,
elastofibroma dorsi,
intramuscular lipomas and among the lesion of the soft tissues,
particular clinical relevance is attributed to the benign and malignant diseases of the breast.
Although in general they are easy to identify,
in some cases they can be misunderstood because of the clinical request that focuses radiologists’ attention elsewhere: they are non-diagnoses that can have serious consequences on outcomes in appropriate clinical settings (FIG 9).
Bones
Costal fractures are certainly among the most interesting bone palilogies in common clinical practice; these pathologies can be associated with pain and functional impotence,
but it is not uncommon for the symptoms to be very blurred and therefore may not be the primary objective of a CT assessment.
In our experience it is common to find these lesions in the absence of a positive history of recent traumas; although often asymptomatic,
they may be associated with vascular lesions,
nerve injuries,
pneumothorax,
parenchymal herniation and bleeding; the number of displaced fractures is inter alia correlated with an increase in severe pulmonary complications [6] (FIG 10).
Even vertebral collapses can go unrecognized: the recognition of this type of lesions requires the evaluation of reformatting on the sagittal plane (FIG 11).
Muscle
Elastofibroma dorsi is a benign soft tissue tumor located in the intrascapular region,
bilaterally or not; in most cases it remains asymptomatic,
but can sometimes be associated with pain.
In CT it appears as a hypo-isodense mass compared to muscles [7].
The importance of this lesion lies in the possibility of making a diagnostic error with respect to other pathologies,
benign or malign,
of the soft tissues and muscles (FIG 12).
Lipomas are the most common benign tumors in the adult population may be misunderstood as a result of a superficial evaluation of a CT scan performed for other reasons.
In our series we have noticed several cases of intramuscular lipomas.
Lipomas present themselves as well-defined lesions of variable size in the soft tissue context,
with attenuation values equal to those of fat.
The clinical importance is due to the possible association in syndromic diseases (FIG.
13) [8].
From our series we extracted a case of latissimus dorsi lipoma,
a condition often characterized by pain and functional impotence of the upper limb probably correlated with localized microtrauma of the axillary region (Fig 14) [9].