A 70 year old male with a large anterior mediastinal mass.
1.What's the morphology impression?
A: Germ cell tumor, favor yolk sac tumor
B: Ewing sarcoma
C: CIC-DUX sarcoma
D: Sarcoma with BCOR rearrangements
E: Rhabdomyosarcoma
F: Melanoma
G: Poorly differentiated carcinoma
H: MPNST
2.What's your panel of work up?
IHC
Pan-keratin
WT1
CD99
SALL4
You can vote for more than one answer.
Answer
A limited panel was performed. The lesional cells to be diffusely positive for myogenin, with patchy expression of desmin and glypican 3, retained h3k27me expression, and no significant expression of SALL4, keratin, SOX10 and S100. CD99, BCOR, WT1 are all negative. You are about to sign out the case while waiting for molecular test. What's the favored diagnosis at this point?
A: Germ cell tumor, favor yolk sac tumor
B: Ewing sarcoma
C: CIC-rearranged sarcoma
D: Sarcoma with BCOR rearrangements
E: Rhabdomyosarcoma
F: Melanoma
G: Poorly differentiated carcinoma
H: MPNST
Answer
The case was sent for sarcoma fusion panel and a PAX3-FOXO1 fusion was detected. What's the following statement is true?
A: PAX3-FOXO1 can be seen in embryonal rhabdomyosarcoma.
B: The presence of small round tumor cells and differentiating rhabdomyoblasts in this case represent embryonal rhabodomysarcoma.
C: PAX7-FOXO1 in alveolar rhabdomyosarcoma has worse prognosis
D: Given the PAX3-FOXO1 fusion, this case is alveolar rhabdomyosarcoma
Answer
References:
Case credit: UCSD Pathology
Author: Wangpan Shi
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