Provided clinical history
14 year old child with cognitive disturbances and hydrocephalus.
Site
Left thalamus.
Primary image
Low magnification. H&E stain.
Intermediate magnification

Intermediate magnification. H&E stain.

High magnification

High magnification. H&E stain.

Differential diagnosis
Additional tests
More history
More history

There is no further information available

Ask a colleague
Ask a colleague

The elongated cell processes have a glial appearance

Stains
Alcian blue/PAS to Bilirubin 

Test  Result 
Alcian blue/PAS  No need for additional PAS staining here 
Alican blue pH 1.0  
Alcian blue pH 2.5  
Auramine  Dr Torres would ask why! 
Bielchowsky  Dr Torres would ask why! 
Bilirubin  Dr Torres would ask why! 



Colloidal iron to FontanaMasson 

Test  Result 
Colloidal iron  Dr Torres would ask why! 
Congo red  Dr Torres would ask why! 
Cresyl violet  Dr Torres would ask why! 
Dieterle  Dr Torres would ask why! 
Diff Quik  Dr Torres would ask why! 
FontanaMasson  Dr Torres would ask why! 



Gallyas to Gremelius 

Test  Result 
Gallyas  Dr Torres would ask why! 
Giemsa  Dr Torres would ask why! 
GMS  Dr Torres would ask why! 
Gomori's trichrome  Dr Torres would ask why! 
Gram  Dr Torres would ask why! 
Gremelius  Dr Torres would ask why! 



JMS to Mucicarmine 

Test  Result 
JMS  Dr Torres would ask why! 
Jones  Dr Torres would ask why! 
Kinyoun  Dr Torres would ask why! 
Luxol fast blue  Dr Torres would ask why! 
Masson trichrome  Dr Torres would ask why! 
MMAS  Dr Torres would ask why! 
Movat  Dr Torres would ask why! 
Mucicarmine  Dr Torres would ask why! 



Oil red O to Prussian blue 

Test  Result 
Oil red O  Dr Torres would ask why! 
Orecein  Dr Torres would ask why! 
PAS  Dr Torres would ask why! 
PASD  Dr Torres would ask why! 
PASF  Dr Torres would ask why! 
PTAH  Dr Torres would ask why! 
Prussian blue  Dr Torres would ask why! 



Reticulin to ZiehlNeelsen 

Test  Result 
Reticulin  Dr Torres would ask why! 
Sudan black B  Dr Torres would ask why! 
Toluidine blue  Dr Torres would ask why! 
Verhoeff  Dr Torres would ask why! 
Von Kossa  Dr Torres would ask why! 
WarthinStarry  Dr Torres would ask why! 
ZiehlNeeslen  Dr Torres would ask why! 



IHC
Alpha1 AT to Cathepsin K 

Test  Result 
alpha1 AT  Dr Torres would ask why! 
ACTH  Dr Torres would ask why! 
AE1/AE1  NEGATIVE 
alphafetoprotein  Dr Torres would ask why! 
AlkI  Dr Torres would ask why! 
AMACR  Dr Torres would ask why! 
AR  Dr Torres would ask why! 
ATRX  NO LOSS 
Beta2microglobulin  Dr Torres would ask why! 
B72.3  Dr Torres would ask why! 
Betacatenin  Dr Torres would ask why! 
BCL2  Dr Torres would ask why! 
BCL6  Dr Torres would ask why! 
BCLxL  Dr Torres would ask why! 
C3 comp  Dr Torres would ask why! 
CA9  Dr Torres would ask why! 
Calcitonin  Dr Torres would ask why! 
Calponin  Dr Torres would ask why! 
Calretinin  Dr Torres would ask why! 
CAM5.2  NEGATIVE 
Cathepsin K  Dr Torres would ask why! 



CD10 to Chromogranin 

Test  Result 
CD10  Dr Torres would ask why! 
CD117  Dr Torres would ask why! 
CD138  Dr Torres would ask why! 
CD15  Dr Torres would ask why! 
CD1a  Dr Torres would ask why! 
CD20  Dr Torres would ask why! 
CD21  Dr Torres would ask why! 
CD23  Dr Torres would ask why! 
CD3  Dr Torres would ask why! 
CD30  Dr Torres would ask why! 
CD31  Dr Torres would ask why! 
CD34  Dr Torres would ask why! 
CD35  Dr Torres would ask why! 
CD4  Dr Torres would ask why! 
CD43  Dr Torres would ask why! 
CD45 (LCA)  NEGATIVE 
CD5  Dr Torres would ask why! 
CD56  Dr Torres would ask why! 
CD57  Dr Torres would ask why! 
CD68  Dr Torres would ask why! 
CD7  Dr Torres would ask why! 
CD79a  Dr Torres would ask why! 
CD8  Dr Torres would ask why! 
CD99  Dr Torres would ask why! 
CDX2  Dr Torres would ask why! 
CEAm  Dr Torres would ask why! 
Chromogranin  Dr Torres would ask why! 



CK17 to Glypican 3 

Test  Result 
CK17  Dr Torres would ask why! 
CK19  Dr Torres would ask why! 
CK20  Dr Torres would ask why! 
CK34betaE12  Dr Torres would ask why! 
CK5/6  Dr Torres would ask why! 
CK7  Dr Torres would ask why! 
CMV  Dr Torres would ask why! 
cMYC  Dr Torres would ask why! 
Cyclin D1  Dr Torres would ask why! 
D240  Dr Torres would ask why! 
Desmin  Dr Torres would ask why! 
DOG1  Dr Torres would ask why! 
EBV  Dr Torres would ask why! 
EMA  Dr Torres would ask why! 
ER and PR  Dr Torres would ask why! 
Factor VIII  Dr Torres would ask why! 
Factor XIIIa  Dr Torres would ask why! 
Fascin  Dr Torres would ask why! 
FH  Dr Torres would ask why! 
FSH  Dr Torres would ask why! 
Gastrin  Dr Torres would ask why! 
GATA3  Dr Torres would ask why! 
GCDFP15 (BRST2)  Dr Torres would ask why! 
GFAP  POSITIVE 
GH  Dr Torres would ask why! 
Glucagon  Dr Torres would ask why! 
Glypican3  Dr Torres would ask why! 



HBME1 to IgM 

Test  Result 
HBME1  Dr Torres would ask why! 
HBV core  Dr Torres would ask why! 
HBV surface  Dr Torres would ask why! 
Hcaldesmon  Dr Torres would ask why! 
HCG  Dr Torres would ask why! 
Helicobacter  Dr Torres would ask why! 
Hepatocyte  Dr Torres would ask why! 
HER2/neu  Dr Torres would ask why! 
HHV8  Dr Torres would ask why! 
HMB45  Dr Torres would ask why! 
HNF1beta  Dr Torres would ask why! 
HPV  Dr Torres would ask why! 
HSVI  Dr Torres would ask why! 
HSVII  Dr Torres would ask why! 
IDH1  NEGATIVE 
Inhibin  Dr Torres would ask why! 
INI1 (BAF47)  Dr Torres would ask why! 
Insulin  Dr Torres would ask why! 
Kappa  Dr Torres would ask why! 
Ki67  2% 
Lambda  Dr Torres would ask why! 
Leu 7  Dr Torres would ask why! 
IgA  Dr Torres would ask why! 
IgG  Dr Torres would ask why! 
IgM  Dr Torres would ask why! 



LH to PDGFR 

Test  Result 
LH  Dr Torres would ask why! 
LIN28  Dr Torres would ask why! 
Lysozyme  Dr Torres would ask why! 
mammoglobin  Dr Torres would ask why! 
MAP2  Dr Torres would ask why! 
MCV  Dr Torres would ask why! 
Melanin A  Dr Torres would ask why! 
MHC class I  Dr Torres would ask why! 
MITF  Dr Torres would ask why! 
MUM1  Dr Torres would ask why! 
Myeloperoxidase  Dr Torres would ask why! 
MYO D1  Dr Torres would ask why! 
Myoglobin  Dr Torres would ask why! 
Napsin  Dr Torres would ask why! 
NF  NEGATIVE 
NKX3.1  Dr Torres would ask why! 
NSE  Dr Torres would ask why! 
OCT3/4  Dr Torres would ask why! 
p16  Dr Torres would ask why! 
P501S  Dr Torres would ask why! 
p53  Dr Torres would ask why! 
p57  Dr Torres would ask why! 
p63  Dr Torres would ask why! 
Pankeratin  Dr Torres would ask why! 
PAX2  Dr Torres would ask why! 
PAX5  Dr Torres would ask why! 
PAX8  Dr Torres would ask why! 
PCNA  Dr Torres would ask why! 
PDGFR  Dr Torres would ask why! 



PLAP to WT1 

Test  Result 
PLAP  Dr Torres would ask why! 
PNL2C  Dr Torres would ask why! 
Prolactin  Dr Torres would ask why! 
PSA  Dr Torres would ask why! 
PSAP  Dr Torres would ask why! 
RCC  Dr Torres would ask why! 
S100  Dr Torres would ask why! 
SALL4  Dr Torres would ask why! 
Smooth muscle actin  Dr Torres would ask why! 
Somatostatin  Dr Torres would ask why! 
STAT6  Dr Torres would ask why! 
Synaptophysin  NEGATIVE 
TdT  Dr Torres would ask why! 
TFE3  Dr Torres would ask why! 
TFEB  Dr Torres would ask why! 
Thyroglobulin  Dr Torres would ask why! 
Toxoplasma  Dr Torres would ask why! 
TSH  Dr Torres would ask why! 
TTF1  Dr Torres would ask why! 
Ubiquitin  Dr Torres would ask why! 
UCHL1 (PGP9.5)  Dr Torres would ask why! 
Ulex Europaeus  Dr Torres would ask why! 
Vimentin  POSITIVE 
VIP  Dr Torres would ask why! 
VZV  Dr Torres would ask why! 
WT1  PARTIALLY POSITIVE 



Molecular testing
Chromosomal translocations
Translocations Chr 110 

Test  Result 
t(1;13) PAX7FKHR  Dr Torres would ask why! 
t(2,13) PAX3FKHR  Dr Torres would ask why! 
t(8;14) MYCIGH  Dr Torres would ask why! 
t(9;22) BCRABL  Dr Torres would ask why! 
t(9;22) CHNEWS  Dr Torres would ask why! 



Translocations Chr 1113 

Test  Result 
t(11;14) CCND1IGH  Dr Torres would ask why! 
t(11;22) EWSWT1  Dr Torres would ask why! 
t(11;22) FLI1EWS  Dr Torres would ask why! 
t(12;15) ETV6NTRK3  Dr Torres would ask why! 
t(12;16) FUSATF1  Dr Torres would ask why! 
t(12;16) CHOPTLS  Dr Torres would ask why! 
t(12;22) EWSATF1  Dr Torres would ask why! 



Translocations Chr 1422 

Test  Result 
t(14,18) IGHBCL2  Dr Torres would ask why! 
t(15;17) PMLRARA  Dr Torres would ask why! 
t(16;21) FUSERG  Dr Torres would ask why! 
t(17;22) COLA1PDGFB  Dr Torres would ask why! 
t(21;22) EWSERG  Dr Torres would ask why! 



Translocations Chr X & Y 

Test  Result 
t(X;1) PRCCTFE3  Dr Torres would ask why! 
t(X;17) TFE3ASPL  Dr Torres would ask why! 
t(X;18) SYTSSX  Dr Torres would ask why! 



Other molecular tests
Molecular tests (AB) 

Test  Result 
ALK sequencing  Dr Torres would ask why! 
B cell clonality Southern / PCR  Dr Torres would ask why! 
BCL2 PCR  Dr Torres would ask why! 
BRAF sequencing  KIAA1549(Exon15)BRAF(Exon9) TRANSCRIPT FOUND 



Molecular tests (CH) 

Test  Result 
EBV PCR  Dr Torres would ask why! 
EGRF sequencing  Dr Torres would ask why! 
H3F3A sequencing  WILDTYPE 
HHV8 PCR  Dr Torres would ask why! 



Molecular tests (IJ) 

Test  Result 
Identity testing PCR  Dr Torres would ask why! 
IDH1/2 PCR  WILDTYPE 
JAK2 V617F ARMS  Dr Torres would ask why! 



Molecular tests (KZ) 

Test  Result 
KIT sequencing  Dr Torres would ask why! 
LOH 1p/19q PCR  NO LOH 1p/19q 
T cell clonality Southern / PCR  Dr Torres would ask why! 



Diagnosis
Diagnosis

PILOMYXOID ASTROCYTOMA GRADE II WHO WITH KIAA1549(Exon15)BRAF(Exon9) FUSION
Comment: Pilomyxoid astrocytomas are a variant of pilocytic astrocytoma and share the same genetic abberations such as KIAA1549BRAF fusions as seen in the current case. They usually lack the typical compact areas with rosenthal fibers seen in pilocytic astrocytomas. The tumors have been designated as WHO grade II tumours in the 2007 WHO classification, because of their tendency to recur more often.^{[1]} A hypothalamic/chiasmatic location itself is a adverse prognostic factor.^{[2]}
References
 ↑ Brat, DJ.; Scheithauer, BW.; Fuller, GN.; Tihan, T. (Jul 2007). "Newly codified glial neoplasms of the 2007 WHO Classification of Tumours of the Central Nervous System: angiocentric glioma, pilomyxoid astrocytoma and pituicytoma.". Brain Pathol 17 (3): 31924. doi:10.1111/j.17503639.2007.00082.x. PMID 17598825.
 ↑ Colin, C.; Padovani, L.; Chappé, C.; Mercurio, S.; Scavarda, D.; Loundou, A.; Frassineti, F.; André, N. et al. (Oct 2013). "Outcome analysis of childhood pilocytic astrocytomas: a retrospective study of 148 cases at a single institution.". Neuropathol Appl Neurobiol 39 (6): 693705. doi:10.1111/nan.12013. PMID 23278243.

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Lymph node pathology (jr,sr, f/e)
Medical kidney pathology (jr,sr, f/e)
Molecular pathology (jr,sr, f/e)
Neuropathology (jr,sr, f/e)
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Pulmonary pathology (jr,sr, f/e)
Placental pathology (jr,sr, f/e)
Soft tissue pathology (jr,sr, f/e) 

 Difficulty  

