DISCUSSION
BAA is a rare vascular entity which can be broadly classified based on
its localization into either mediastinal or intrapulmonary BAA [4].
Although all BAA can be found incidentally in patients with no symptoms,
the latter frequently presents with hemoptysis. Mediastinal BAA on the
other hand can present with a variety of symptoms resulting from
extrinsic compression of contiguous structures including atelectasis,
dysphagia, and superior vena cava syndrome [9]. Occasionally, the
aneurysm may rupture, resulting in an acute and life-threatening
condition characterized by chest pain, hemothorax, hemomediastinum,
hematemesis, and shock [10].
In our case, the presenting symptom was unilateral periscapular pain,
which is an atypical referring pattern for pain originating from the
mediastinum. Although such a pattern has been demonstrated before in
thymic carcinomas [11], lymphomas [12], or sarcomas [13]
infiltrating the intercostal nerves, the pericardium, or vertebrae, such
infiltration was not revealed on imaging in our patient. The
viscerosomatic convergence theory might therefore provide a better
explanation [14]. This theory states that noxious stimuli from a
diseased organ can transmit to an adjacent normal structure, resulting
in functional changes in the latter. This phenomenon is mediated by
convergence of visceral and somatic afferent neurons at the level of the
spinal cord, in lamina I and V of the dorsal horn, and results in
afferent stimuli of the viscera being interpreted by the brain as
dermatomal and sclerotomal pain. Viscerosomatic convergence might
therefore be a possible mechanism of pain in patients presenting with
BAA. In addition to the periscapular pain, our patient experienced
shortness of breath, hoarseness, and dysphagia, all symptoms that are
compatible with extrinsic compression of surrounding structures by the
BAA.
In conclusion, we presented the case of a 60-year old woman with
unilateral periscapular pain as an atypical presentation of three
posterior mediastinal BAAs. The diagnosis was suspected based on chest
X-ray and consequently confirmed on chest CT and selective bronchial
arteriography. BAAs were removed successfully via thoracotomy, with
excellent recovery and relief of the periscapular pain.