Clinical history: 6 month old child with retroperitoneal mass.
What is the most probable diagnosis?
You are seeing a small round blue cell tumor (minimal cytoplasm, hyperchromatic round nuclei). On low power you can appreciate a very fibrous stroma with islands of crushed small round blue cells. On higher power you can see that the small round blue cells are admixed with neuropil (the fluffly light pink fibrillary matrix). There is no schwannian stroma.
For exams know:
It is the most common solid malignancy in children (excluding brain tumors)
80% before age 4
It is on your differential list for small round blue cell tumors
It is derived from neural crest cells capable of multilineage differentiation
Occurs in adrenal medulla (1/4th) or along sympathetic chain
Associated with Beckwith--Wiedemann syndrome, Hirschsprung disease, neurofibromatosis type 1, and Cushing syndrome
Can present with high catecholamine levels in blood
Mets are usually early and widespread to bone, however up to 30% spontaneously regress or mature to ganglioneuroma (although these ones are usually not the ones that are detected)
NPC classifies these into Classic (undifferentiated), Poorly differentiated, and Differentiating neuroblastomas
Immunohistochemistry shows positivity for chromogranin, synaptophysin, neurofilament, NSE, and ALK
Can have N-myc amplification (the higher, the worse the prognosis)