How will you differentiate a mediastinal mass being a thymoma or acute lymphoblastic leukemia?
Ans. A. CytokeratinA mediastinal mass has a differential of thymoma and T-cell ALL. T-cell ALL will have the markers TDT (lymphoblast), CD la and CD3. Thymoma has 2 components--epithelial and lymphoid components--so is positive for EMA, cytokeratin 7 and 20,CD57CD5,bcl-2, calretinin, vimentin, CD3,CD1a,CD20,CD99.
Cytokeratin
CD1a
CD3
Tdt
Neoplasia