PEDIATRICS Section 6: Mediastinum Flashcards
The most common ANTERIOR mediastinal “mass”
Normal Thymus
Triangular shape of the thymus is called?
“Sail Sign”
Diagnosis? Sign?
the spinnaker sail sign, which is when pneumomediastinum lifts up the thymus.
what are the things that makes you think thymus is a cancer?
Abnormal Sizefor patients Age (really big in a 15 year old)
* Heterogenous appearance * Calcification
* Compression of airwayor vascular structure
In times of acute stress (pneumonia, radiation, chemotherapy, bums), the thymus will shrink. In the recovery phase it will rebound back to normal, and sometimes larger than before.
Thymic rebound (Can be PET avid)
Most common abnormal mediastinal mass in children (Older children and teenagers)
Lymphoma
Difference between Thymus and Lymphoma
Thymus is more in kids under 10,
Lymphoma is seen more in kids over 10.
When you see a mediastinal mass with calcifictaion, think of?
Teratoma
Can be seen in untreated lymphoma
What are the complications of Lymphoma?
Compresssion of SVC
Compression of Pulmonary veins
Pericardial effusion
Airway compression
This condition can appear very similar to Lymphoma (Soft tissue mass in anterior mediastinum). This cannot be differentiated on imaging alone
ALL (Acute lymphoblastic Leukemia)
a large anterior mediastinal mass arising from or at least next to the thymus.
Germ Cell Tumor (GCT)
What are the three Germ Cell Tumors?
Describe each.
- Teratoma
- Seminoma
- Non-Seminomanous GCT
GCT: Mostly Cystic, with fat and calcium
Teratoma
GCT: Bulky, solid and lobulated. “Straddles the midline”
Seminoma
GCT: Big and Ugly - Hemorrhage and Necrosis. Can get crazy and invade the lung.
Non. Seminomatous GCT
I say, Extra Gonadal Germ Cell Tumor, You say? (describe)
Klinefelter syndrome (47XXY)
They have small penises, they get male breast cancer, and as if things couldn’t possibly get worse… they get germ cell tumors in their chest.
300x risk of getting GCT
Pineal gland GCT can occur - vertical gaze palsy
In that case, they can’t even look up to the sky and say “Why God* ?! Why Me!? Why Klinefelter’s!?”
**God, Allah, Mother Earth, Celestial Deity not otherwise specified
What are the anterior mediastinal masses?
Thymus
Lymphoma
GCT
Thymic rebound
What are the middle mediastinal masses?
Lymphadenopathy
Duplication Cysts
Middle mediastinal lymphadenopathy is most often from?
Granulomatous disease (TB or Fungal) or from lymphoma
Causative agent of Mononucleosis
EBV (90%)
CMV (10%)
Classic scenario of Mononucleusis?
Adolescent with hilar adenopathy, splenomegaly, and fatigue.
Enumerate the types of mediastinal adenopathy
- Mononucleusis
- Primary TB
- Histoplasmosis
- Coccidiodomycosis
- Lymphoma
- Sarcoid
Rash after antibiotics
Mononucleosis
Describe the medastinal adenopathy in Primary TB
Distribution of nodes in usually unilateral, right hilar, right paratracheal
Lower and Middle lobe consolidation is common
Hilar lymph node involvement (usually bilateral) is more common with what type of lymphoma?
Hodgkin
What are the 3 categories of Duplication cysts?
a. Bronchogenic
b. Enteric
c. Neuroenteric
Diagnosis? Describe
Mediastinal Bronchogenic Duplication Cyst
water attenuation - close to the trachea or bronchus.
- Tend to be middle mediastinal (70%), the rest are in the hilum
- Typically filled with mucus or fluid
Diagnosis? Describe
water attenuation close to the esophagus (lower in the mediastinum)
- Abutment of the esophagus is the key finding.
- Can communicate with the lumen of the esophagus - and have air/fluid levels.
- Usually on the right, involving the distal esophagus
- Can be middle or posterior mediastinal in location
- Second most common GI lumen duplication cyst (distal ileum #1)
What is the 1st and 2nd most common GI lumen duplication cyst
1: Ileum
#2: Esophageal
This is the most common posterior mediastinal mass in a child UNDER 2
Neuroblastoma
What are the posterior mediastinal masses in children?
Neuroblastoma
Ewing Sarcoma
Askin Tumor
Neuroenteric Cyst
Extramedullary Hematopoeisis
Diagnosis?
Thoracic neuroblastoma
It may involve the ribs and vertebral bodies (on X-rays look for rib splaying and erosions
Which has better prognosis? thoracic or GI neuroblastoma?
ompared to abdominal neuroblastoma, thoracic neuroblastoma has a better outcome.
What other neuroblastic tumors can you have in the posterio mediastinum?
Ganglioneuroma and Ganglioneuroblastoma
Wilms vs Neuroblastoma - Which usually mets in the chest more?
Wilms tumor
When copared with Neuroblasoma, Gangluineuromas are?
- Less Aggressive
- More Circumscribed (less invasive)
- Less Likely to have Calcifications (although they still can)
- Found in Older Children (think 2nd decade) - vs. neuroblastoma (think 1st decade)
What is the primitive Neuroectrodermal tumor of the chest wall?
Askin Tumor
This is now considered part of the Ewing Sarcoma spectrum, and is sometimes called an Ewing sarcoma of the chest wall.
They tend to displace adjacent structures rather than invade early on (when they get big they can invade). They look heterogenous, and the solid parts will enhance.
Askin tumor
cyst protruding out of an unsealed canal / defect
Neuroenteric Cyst
Diagnosis? There are associated with what type of anomalies?
Describe
Neuroenteric cyst
Associated with Vertebral anomalies (Scoliosis, hemivertebrae, butterfly vertebrae, split cord, etc..)
does NOT communicate with CSF,
is well demarcated,
water density. F
avor the lower cervical and thoracic regions.
This occurs in patients with myeloproliferative disorders or bone marrow infiltration (including sickle cell).
Extramedullary Hematopoiesis
How does Extramedullary Hemaopoiesis manifest?
this manifests as a big liver and big spleen and in minority of cases, and in a minority of cases a soft tissue density in the spine (paraspinal masses - usually below T6), which are bilateral, smooth, and sharply delineated
When you see an anterior mediastinal mass, assume it’s?
Hodgkins (4x more common in NHL)
Hodgkins involves the thymus 90% of the time.
Q: How the hell do you tell a big ass normal thymus in a little baby vs a lymphoma?
A: My main move is to go age.
Under 10 = Thymus,
Over 10 = Lymphoma.
In anterior mediastinal masses, when you see a
history like this:
“got off chemo” or “got off corticosteroids”
Think of what?
Thymic Rebound
Homogeneous soft tissue mass in the anterior mediastinum
Lymphoma or hyperplasia
Fat containting mass in the anterior mediastinum
Germ Cell Tumor (Why God!? Why Klinefeters?)
Water density in the anterior mediastinum?
think of congenital stuff - Lymphangiomas
what is teh first rule in the pediatric multiple choice taking>?
TIMING! AGE!
Posterior Mediastinal mass + Under 10 =
Think malignant - think neuroblastoma
Posterior Mediastinal mass + 2nd decade =
Think benign
Posterior Mediastinal ROUND mass =
Ganglioneuromas & Neurofibromas
Posterior Mediastinal CYSTIC mass
Neuroenteric Cyst
If they show you coarse bone trabeculation in a posterior mediastinal mass + adjacent mass or hx of anemia =
Think Extramedullary Hematopoiesis
If you see a BFM (Big fucking mass) in the chest of a kid, you basically have two choices:
(1) Askin Tumor (PNET / Ewings) -
(2) Pleuropulmonary Blastoma
BFM (Big fucking mass) + Age 10+ + Etean up rib =
Askin Tumor (PNET/Ewings)
BFM (Big fucking mass) + < 2y.o. =
Pleuropulmonary Blastoma
