The use of prothymosin alpha as a surrogate for thymosin α1 was previously demonstrated in literature for radioimmunoassays.[20, 30] Our proteomics analysis of FFPE archival tissue revealed that in comparison to normal thymus tissue thymoma of AB, B1 and B2 types show an increase in prothymosin alpha while thymomas A and B3 show a lower level of prothymosin alpha, consistent with expected levels of T lymphocytes. Here, PTMA is linked to thymoma.