HY lecture notes:
Craniopharyngioma –> answer for pituitary tumor in peds –> can calcify –> can have cholesterol deposits + “motor oil” appearance on biopsy –> contains squamous epithelium –> known to recur following resection.
If grows laterally, CN VI (abducens) is affected first due to medial location of the nerve in the cavernous sinus.
If grows upward, this will cause bitemporal hemianopsia due to impingement on CN II at the optic chiasm.
Derived from Rathke pouch (so not true pituitary tumor according to some sources).
Most common primary brain tumor overall in peds is pilocytic astrocytoma –> solid + cystic in appearance on MRI + contains Rosenthal fibers.
Medulloblastoma is second-most common in peds –> grows from the cerebellum, not medulla –> aggressive (in contrast to pilocytic astrocytoma).
Posterior urethral valves are most common genitourinary abnormality in neonatal males –> valves within the urethra face the wrong direction –> causes inability to urinate.
Dx of PUV is voiding cystourethrogram. Tx is surgical.
They will tell you an 24-hour-old male has a suprapubic mass –> full bladder –> answer = voiding cystourethrogram, or simply, posterior urethral valves.
If they tell you there’s a painless flank mass in a 3-4 year-old, answer = Wilms tumor. Sounds obvious, but I see this mistake in students a lot: Wilms tumor won’t develop until a few years of age. PUV is literally in neonates (first several days of life).
Wilms tumor can present alone or in constellation with various syndromes:
WAGR –> Wilms tumor, Aniridia, Genitourinary abnormalities, Retardation.
Denys-Drash syndrome –> Wilms tumor + pseudohermaphroditism (WT1 mutation).
Beckwith-Weidemann syndrome –> macrosomia (>4000g birth weight), hemi-hypertrophy, macroglossia, neonatal hypoglycemia –> go on to develop Wilms tumor (WT2 mutation)
Wilms tumor can present in horseshoe kidney of Turner syndrome.
Do renal ultrasound to Dx Wilms tumor. (extraordinarily rare to do CTs on kids).
Neuroblastoma –> usually n-myc gene; grows from median sympathetic chain (in the midline) –> will present usually as midline mass in a kid 3-8 years old.
Reiteration: Neuroblastoma is midline; Wilms is lateral flank mass. Not difficult, but I see students mess this up.
Neuroblastoma can present classically with “dancing eyes” (opsoclonus-myoclonus syndrome) –> weird, but HY.
Neuroblastoma can also present with hypertension –> Dx with urinary homovanillic acid (HVA) and vanillylmandelic acid (VMA).
This is contrast to pheochromocytoma in adults, for instance, which is diagnosed with urinary or serum metanephrines (you’ll often see this as another answer choice).
Weird but important detail: neuroblastoma can present in THE POSTERIOR MEDIASTINUM –> there’s a Q on one of the peds forms where they say there’s a mass in the posterior mediastinum; the kid didn’t have HTN or any other typical findings of neuroblastoma, but it was the answer. Thymoma was wrong, as this is in the anterior, not posterior, mediastinum. Apparently neuroblastoma can be in the posterior mediastinum as this is still consistent with the median sympathetic chain.
Failure to pass meconium at birth –> cystic fibrosis –> answer = “exocrine pancreas insufficiency.”
Hirschsprung –> “failure of migration of neural crest cells” –> seen in Down syndrome
Duodenal atresia –> also seen in Down syndrome –> bilious vomiting + double-bubble sign seen on AXR.
