Immunohistochemical diagnosis of gastrointestinal stromal tumors - an analysis of 80 cases from 2004 to 2010.

Gastrointestinal stromal tumors (GISTs) are the most common cancers of mesenchymal origin in the abdomen. An approximately 95% of GISTs show positive expression of the membrane receptor c-kit (CD117 antigen), which currently constitutes the basis for histopathological diagnosis if this type of tumor is suspected. The aim of this study was to perform and investigate wide parametric immunohistochemical and morphological analyses of stromal tumors diagnosed in the Podlasie province in the years 2004-2010. The study group consisted of 80 patients who had undergone surgical treatment for mesenchymal tumors of the gastrointestinal tract. The immunostaining technique was performed using the surgically resected material that was formalin-fixed and embedded in paraffin blocks, then sliced into sections and stained with the monoclonal antibodies CD117, CD34, SMA, S-100 and Ki-67. CD117 was positively expressed in 77 cases, which confirmed the diagnosis of GIST. In 66 of the cases of CD117-positive stromal tumors, positive immunoreactivity for CD43 was observed. Nearly 49% (38 cases) of the GISTs were negative for SMA by immunohistochemistry. Most of the cases (57.5%) were reported in the stomach, while 17.5% were located in the intestines; 18.75% presented in different locations (the colon, ovary or gall bladder). The use of a highly sensitive IHC panel can increase the accuracy of GIST diagnoses. Detailed immunohistochemical studies are useful in successfully identifying any case of GIST, which is crucial to clinical treatment.