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Question:
Based on the initial images only, what is your first impression?
Based on the initial images only, what is your first impression?
More images
CD99
Question
What are your feelings now?
What are your feelings now?
Cam 5.2 and EMA
CD56 and CD57
NSE
Desmin
Negative stains:
WT-1
Myogenin
WT-1
Myogenin
Question:
What is your final diagnosis?
*Desmoplastic small round cell tumour
What is your final diagnosis?
*Desmoplastic small round cell tumour
Last image
Diagnosis:
Desmoplastic small round cell tumour (DSRCT)
Presenting as a primary testicular tumour.
EWSR translocation present.#BSTpath
Question:
In males, DSRCTs are more commonly found in the?
In males, DSRCTs are more commonly found in the?
1/ This aggressive tumour classically occurs in the pelvis, mainly males and occasionally females (mean age 20 years).
2/ Paratesticular tumours are rarer and testicular primaries even more so. https://pubmed.ncbi.nlm.nih.gov/9042290/
2/ Paratesticular tumours are rarer and testicular primaries even more so. https://pubmed.ncbi.nlm.nih.gov/9042290/
3/ This was difficult from a clinical point of view due to the presentation as a suspected primary germ cell tumour.
4/ Below is a
pre-print article discussing primary DSRCT of the testis. https://www.authorea.com/users/366445/articles/486209-a-testicular-and-paratesticular-localization-of-desmoplastic-small-round-cell-tumor-is-it-a-good-prognostic-factor
4/ Below is a
pre-print article discussing primary DSRCT of the testis. https://www.authorea.com/users/366445/articles/486209-a-testicular-and-paratesticular-localization-of-desmoplastic-small-round-cell-tumor-is-it-a-good-prognostic-factor
Question:
Which of the following immunohistochemical stains is often positive in these tumours?
Which of the following immunohistochemical stains is often positive in these tumours?
5/ The tumour shows multiphenotypic differentiation, i.e. it expresses
Neural
CD56, CD57, NSE
Muscle
Desmin (myogenin or MYOD1)
Epithelial markers
Keratins, EMA, Ber-EP4
6/ The below article discusses the above. https://journals.lww.com/ajsp/Fulltext/1998/11000/Desmoplastic_Small_Round_Cell_Tumor__II__An.2.aspx
Neural CD56, CD57, NSEMuscle Desmin (myogenin or MYOD1)Epithelial markersKeratins, EMA, Ber-EP46/ The below article discusses the above. https://journals.lww.com/ajsp/Fulltext/1998/11000/Desmoplastic_Small_Round_Cell_Tumor__II__An.2.aspx
Question:
What translocation does this tumour classically harbour?
What translocation does this tumour classically harbour?
7/ The most common translocation is EWSR1-WT1 (t(11;22)(p13;q12).
8/ Cases with ERG and FLI1 have been reported, but these may be variants of Ewings?? https://journals.lww.com/ajsp/Abstract/1992/04000/A_Novel_Reciprocal_Chromosome_Translocation.10.aspx
8/ Cases with ERG and FLI1 have been reported, but these may be variants of Ewings?? https://journals.lww.com/ajsp/Abstract/1992/04000/A_Novel_Reciprocal_Chromosome_Translocation.10.aspx
Question:
What does the EWSR1-WT1 translocation do?
*platelet-derived growth factor A
**transforming growth factor-β
What does the EWSR1-WT1 translocation do?
*platelet-derived growth factor A
**transforming growth factor-β
9/ Because of the fusion, WT1 is inactivated
10/ WT1 normally represses PDGF-A + TGF- β (+ others)
11/ Although PDGF-A was thought to be the cause of desmoplasia in these tumours, the below study shows the opposite (i.e. the mechanism is more complex) https://www.nature.com/articles/3800264
10/ WT1 normally represses PDGF-A + TGF- β (+ others)
11/ Although PDGF-A was thought to be the cause of desmoplasia in these tumours, the below study shows the opposite (i.e. the mechanism is more complex) https://www.nature.com/articles/3800264
Last question:
WT-1 immunohistochemistry is positive in?
WT-1 immunohistochemistry is positive in?
12a/ WT-1 immunohistochemistry should show positive nuclear expression however, only to the C-terminus antibody.
12b/ Because of the fusion, in this tumour, a protein containing the zinc finger region of WT1 is only targeted by the C terminus (not N)
https://www.nature.com/articles/3880656.pdf?origin=ppub
12b/ Because of the fusion, in this tumour, a protein containing the zinc finger region of WT1 is only targeted by the C terminus (not N)
https://www.nature.com/articles/3880656.pdf?origin=ppub
