B. Iatrogenic
Discussion
The chest radiograph demonstrates complete opacification of the left
hemithorax with rightward mediastinal shift, concerning for a large
pleural effusion and for the development of tension physiology. The
ventriculoperitoneal shunt (VPS) can be traced down the anterior chest
before tortuously looping up above the right hemidiaphragm to terminate
at the level of T10. This suggests that the VPS tip migrated into the
left hemithorax, resulting in pleural effusion seen as opacification
that obscures the left hemidiaphragm (answer B). Follow up CT chest
confirmed the catheter tip ascending into the left pleural space with
associated large pleural effusion and complete atelectasis of the left
lung.
Clinical presentations of pleural effusion are dependent on the
underlying cause, baseline cardiac and pulmonary status of the patient,
the rate of fluid accumulation in the pleural space, the rate of fluid
drainage, and the lymphatic resorptive capacity. Poor tolerance can be
seen in cases where the rate of accumulation is faster than the rates of
drainage and resorption. This patient’s history suggests an indolent
process in which the shunt migrated at some point prior (unsure weeks or
months), causing the patient to become progressively more symptomatic
as cerebrospinal fluid (CSF) accumulated in her pleural space.
Pleural effusions are the most common presentation of thoracic VPS
displacement in children. Migration can be supradiaphragmatic (in which
the shunt travels through the chest wall) or transdiaphragmatic (in
which the shunt travels through the diaphragm). This can occur due to
imbalances in the positive abdominal pressure and negative intrathoracic
pressure favoring displacement into the thorax. Inflammation from the
shunt tip at the diaphragm can cause local erosion thus creating a path
for the catheter. The CSF continues to drain, eventually overtaking the
absorptive capacity of the pleura, resulting in pleural effusions. Of
note, pleural effusions can also occur in patients with VPS who do not
have shunt migration. This may be due to congenital diaphragmatic
defects (foramen of Bochdalek or foramen of Morgagni), which are
unfortunately very difficult to visualize on imaging. In addition,
there may be impairment in the peritoneum’s absorptive capacity
resulting in accumulation of CSF in the peritoneal cavity followed by
diffusion to the pleural space.1
Other less likely causes of pleural effusion in this patient are of
infectious, cardiac, or malignant etiologies (answers A, C, and D).
Regarding infectious causes, bacterial pneumonia is the most common
cause of pleural effusion in both children and adults, with Staphylococcus aureus and Streptococcus pneumoniae
being the most common pathogens. These patients tend to present more
quickly with acute respiratory symptoms and fever, rather than with slow
increase in oxygen requirement over weeks to months. Pleural effusions
can also result from pathologies that increase left atrial or pulmonary
capillary wedge pressure leading to left heart disease.2
Patients present with symptoms associated with heart failure in addition
to pleural effusion. Pleural effusions from malignancy result from
tumor compression, obstruction, or invasion of pleural surfaces or
pulmonary lymphatics. In addition to the general respiratory symptoms
associated with pleural effusions, patients may have fevers, weight
loss, night sweats, lymphadenopathy, and fatigue. 3
Anaplastic ependymomas rarely metastasize outside the central nervous
system, albeit there are reports of cases in the thorax, liver and lymph
nodes.4
This patient was admitted to the ICU. A left chest tube was placed with one liter of clear output. Pleural fluid grew Staphylococcus epidermidis,
and she was started on broad spectrum antibiotics. She underwent VPS
externalization and EVD placement. The diaphragmatic hole created by the
transdiaphragmatic migration of the shunt was repaired. After two
weeks, her shunt was internalized into her peritoneum and she was
discharged home. At pulmonary follow up a month after her
hospitalization, she was doing well and back to her baseline oxygen
requirement.
References
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Porcaro, F., Procaccini, E., Paglietti, M.G. et al. Pleural
effusion from intrathoracic migration of a ventriculo-peritoneal shunt
catheter: pediatric case report and review of the literature. Ital J Pediatr 44, 42 (2018).
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Efrati O, Barak A. Pleural Effusions in the Pediatric Population. Pediatr Rev. 2002;23(12):417-426. doi:10.1542/pir.23-12-417
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Cashen K, Petersen TL. Pleural Effusions and Pneumothoraces. Pediatrics in Review. 2017;38(4):170-181. doi:10.1542/pir.2016-0088
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Kumar P, Rastogi N, Jain M, et al. Extraneural metastases in anaplastic ependymoma. J Cancer Res Ther. 2007;3(2):102–104. doi: 10.4103/0973-1482.34689.