In this report, we explore an unusual case of adenocarcinoma detected in the sinonasal mucous membrane in order to illustrate the diagnostic decision process in the immunohistochemical diagnosis. The patient is a 86-year-old man with an intranasal mass. In the immunohistochemical study, it was found expression for both PSA and CDX-2, raising the divergent diagnostic possibilities of a prostatic adenocarcinoma metastasis or an intestinal type sinonasal adenocarcinoma. In search for a solution for this diagnostic dilemma, we tried to establish how these immunohistochemical markers could be confronted in a diagnostic decision by defining the qualities that good immunohistochemical markers consist of and how the panel markers may be compared as to these qualities and the diagnostic hypotheses. In this exercise, important aspects of the diagnostic process in pathology are revealed.
PSA; CDX-2; Sinonasal adenocarcinoma; Diagnostic decision-making
