DIAGNOSTICALLY CD34 IS USED AS A MARKER OF IMMATURITY IN THE SETTING OF ACUTE MYELOID LEUKEMIA OR B CELL LYMPHOBLASTIC LEUKEMIA. IT IS ALSO USEFUL IN THE CLASSIFICATION OF SPINDLE CELL NEOPLASMS LIKE GASTROINTESTINAL STROMAL TUMORS, SOLITARY FIBROUS TUMORS, AND ANGIOSARCOMAS.

IMMUNOHISTOCHEMISTRY IS A TECHNIQUE THAT USES ANTIBODIES TO DETECT SPECIFIC PROTEINS IN A TISSUE SAMPLE. PAN-CYTOKERATIN (PAN CK) IS A BROAD MARKER FOR EPITHELIAL CELLS, WHICH ARE THE CELLS THAT LINE MOST ORGANS.

DESMIN IS USEFUL IN THE IDENTIFICATION OF STRIATED & SMOOTH MUSCLE CELLS AND THE TUMORS DERIVED FROM THIS CELL TYPE LIKE RHABDOMYOSARCOMAS & LEIOMYOSARCOMAS.

ESTROGEN RECEPTOR (ER) IS A STEROID HORMONE RECEPTOR COMMONLY USED ALONGWITH PROGESTERONE RECEPTOR (PR) IN THE MANAGEMENT OF WOMEN WITH BREAST CANCER. ER & PR STATUS PROVIDES AN INDICATION OF PROGNOSIS AND POTENTIAL BENEFIT FROM HORMONAL THERAPY. GENERALLY ER & PR POSITIVE TUMORS ARE MORE LIKELY TO RESPOND TO ENDOCRINE THERAPY AND HAVE A BETTER PROGNOSIS, STAGE FOR STAGE AS COMPARED TO RECEPTOR NEGATIVE TUMORS. THIS TEST IS ALSO RECOMMENDED FOR PATIENTS WITH DUCTAL CARCINOMA IN SITU (DCIS) TO PREDICT POTENTIAL BENEFIT OF ENDOCRINE THERAPIES.

VIMENTIN IS AN INTERMEDIATE FILAMENT EXPRESSED BY NORMAL MESENCHYMAL CELLS. IT IS OVEREXPRESSED IN VARIOUS EPITHELIAL CANCERS OF PROSTATE, GASTROINTESTINAL TRACT, BREAST, LUNG, CNS & IN MELANOMA. ITS OVEREXPRESSION CORRELATES WELL WITH ACCELERATED TUMOR GROWTH, INVASION & POOR PROGNOSIS.

PROGESTERONE RECEPTOR (PR) IS A SURROGATE MARKER OF ESTROGEN RECEPTOR (ER) ACTIVITY IN THE MANAGEMENT OF WOMEN WITH BREAST CANCER. ER & PR STATUS PROVIDES AN INDICATION OF PROGNOSIS AND POTENTIAL BENEFIT FROM HORMONAL THERAPY. GENERALLY ER & PR POSITIVE TUMORS ARE MORE LIKELY TO RESPOND TO ENDOCRINE THERAPY AND HAVE A BETTER PROGNOSIS, STAGE FOR STAGE AS COMPARED TO RECEPTOR NEGATIVE TUMORS. THIS TEST IS RECOMMENDED IN PATIENTS WITH NEWLY DIAGNOSED BREAST CANCER AND METASTATIC & RECURRENT BREAST CANCER.