Small round blue cell tumours of childhood

Question 1

Lymphoblastic lymphoma

Answer 1

>80% T cell.
CD45 variable - important not just to do LCA/CD45
TdT+, CD34+, CD3+ (if T cell)
Frequently CD99+
Other: Discohesive, no molding

Question 2

Neuroblastoma

Answer 2

NE markers +
NB84+++
Notable CD99 negativity
Other: Fibrillary stroma, Homer Wright rosettes.
Ganglion cells and scwannian stroma in better differentiated
No molding
N-myc amplifications = poor prognosis

Question 3

Ewing sarcoma

Answer 3

CD99+++
Synap +
Notably CD56 - 
Other: Monomorphic, uniform cells. Homer Wright rosettes, no ganglion cells, no neuropil outside rosettes
80% have EWS-FLI1 translocation

Question 4

Rhabdomyosarcoma, solid alveolar variant

Answer 4

Actin, Desmin, MyoD, Myogenin +
Other: myogenic differentiation
Usually deep muscles of extremities/trunk

Question 5

Wilms tumour

Answer 5

Syn +
Other: High grade, molding, sometimes nodular.
Homer-Wright rosettes.
Isochromosome 17q

Question 6

Retinoblastoma

Answer 6

No specific immunos

Flexner-Wintersteiner rosettes

Question 7

Hepatoblastoma, small cell variant

Answer 7

Diagnosis requires areas of better differentiated hepatoblastoma

Question 8

Desmoplastic small round cell tumour

Answer 8

CK+
Desmin + (dot)
…. need to complete