Gastrointestinal stromal tumors (GISTs) represent a distinct and the most important subset of mesenchymal tumors of the gastrointestinal (GI) tract GISTs occur throughout the GI tract but are usually located in the stomach and small intestine. The cellular origin, differentiation, nomenclature and prognosis of GISTs are controversial. Because GISTs, like the interstitial cells of Cajal, the GI pacemaker cells, express CD117 (c-kit protein), the origin of GISTs from the Cajal cells has recently been suggested. GISTs are also known for their wide variability in clinical behavior and for the difficulty to determine their malignant condition The most reproducible predictors of malignancy are mitotic count >1-5 per10 high-powered fields (HPF), size >5 cm, tumor necrosis, infiltration and metastasis to other sites. However, some tumors with mitotic activity <1/10 HPF may metastasize indicating some uncertainty in malignant potential of GISTs, especially those larger than 5 cm. Recently, mutations in c-kit gene (exon 11) preferentially occur in malignant GISTs and may be a clinically useful adjunct marker in evaluation of GISTs. In conclusion, the strong CD117 expression mostly defines primary GI mesenchymal tumors as GIST. Specific identification of GIST may become clinically important if therapies targeting the c-kit tyrosine kinase activation become available

SažetakUvod: Tumori

New data on apocrine carcinoma of the breast, especially on its unusual pathogenesis, are the facts that justify this study. The aim of this study was to describe the morphological features in both benign apocrine lesions and invasive apocrine carcinomas of the breast. The following apocrine lesions were pointed out: cysts, metaplasia, adenosis, adenoma, borderline malignant lesion, intraductal carcinoma and invasive apocrine carcinoma. Surgical specimens of breast benign and malignant lesions were fixed in formalin, embedded in paraffin blocks and the slides were stained with HE, PAS and immuno- histochemical ABC complex methods, using primary antibodies against: p53, Ki-67, androgen receptor, and GCDFP-15. The criteria of apocrine lesions, as well as classification of apocrine carcinoma were pointed out also. In the discussion we cited literature data about incidence of apocrine lesions in the breast, immunohistochemical, ultrastructural and molecular characteristics of apocrine lesions focusing on differential diagnostic problems between apocrine and nonapocrine lesions, and benign versus malignant apocrine lesion. The authors have suggested that apocrine carcinoma represents unusual type of the breast carcinoma and which may origin from the following precancerous lesions: apocrine hyperplasia, apocrine adenosis, atypical apocrine adenosis and adenoma. Immunohistochemical markers for apocrine differentiation are: GCDFP-15 and androgen receptors. Ki-67 and p53 may be good markers for differentiation between benign and malignant breast apocrine lesions. Positively staining for androgen receptors, not only in apocrine carcinoma of the breast, but also in benign lesions, has led some authors to postulate a possible role of androgens in the stimulation of breast epithelium and the development of apocrine cells and apocrine carcinomas. However, in this stage the clinical significance remains uncertain and follow-up studies will be required to evaluate this issue

Besides the well-known malignant features additional parameters have been found to be high Ki-67 and c-kit stromal expressions, and weak LAP activity in the epithelial part of malignant MPT, as well as mast cells with a high expression of ER.

Salivary gland tumors are neoplasms characterized by a high level of pleomorphism and histological overlap. One tumor may contain several cell types; therefore, it is necessary to include immunohistochemical staining, as well as morphometric analysis of tumor cells as prerequisites for an appropriate diagnosis. Our research included 120 tumors, such as pleomorphic adenoma, Warthin tumor, basal cell adenoma, myoepithelioma, adenoid cystic carcinoma, mucoepidermoid carcinoma, salivary duct carcinoma, polymorphous low-grade carcinoma and myoepithelial carcinoma. The aim of the study was to differentiate benign and malignant tumors based on the characteristics of nuclei. The expression of Ki67 and the morphometric nuclear parameters - area, perimeter, Feret diameter, integrated optical density, circularity, and roundness, were analyzed. It was observed that the Ki67 proliferative index was statistically significantly higher in malignant tumors (P<0.001). Adenoid cystic carcinoma exhibited the highest value, whereas the lowest value was exhibited in basal cell adenoma. Morphometric analysis showed statistically significantly increased values of integrated optical density (P<0.001) and nuclear size parameters (P<0.05) in malignant tumors. The determination of the Ki67 proliferative index and morphometric analysis of the integrated optical density and area can differentiate benign from malignant tumors with high precision. The presented values suggest the obtained results as cut-off values.