Diagnosis of malignant lesions Flashcards
Specimen collection must be
adequate, representative, and properly preserved
Sampling approaches are:
total excision, biopsy, fine needle aspiration, cytology smears
Fixation methods
freezing, formaldehyde (paraffin), glutaraldehyde (e- microscope), refrigeration (molecular analysis)
H&E stain
H: basic, blue, basophilic: nucleic acids, ribosomes
E: acidic, pink, eosinophilic: cytoplasm, proteins
Yellow or brown on H&E stain?
intrinsic cellular pigments, melanin, etc
PAS
stain basal laminae (good for malignant lesions)
Silver stain
stain reticular fibers
Clear structure on H&E?
hydrophobic structures - rich in fat (adipocytes, myelin, golgi)
Oil red O stain
stain fats
Fine-needle aspiration
aspirating cells and attendant fluid with a small bore needle –> cytological examination
Papanicoloau stain is used
to demonstrate cells that have neoplastic characteristics
Avidin-Biotin Conjugation ABC/DAB
specimen + incubation with primary Ab for suspected tumor antigen; incubation with secondary ant-IgG conjugate to biotin; + avidin = complexes with biotin (ABC-tissue) + DAB -> chromogen for brown coloring
Use of ABC/DAB immunohistochemistry
identification of tumors that resemble each other
Immunohistochemistry for intermediate filaments
for malignant tumor identification of origin, tumor cells contain intermediate filaments consistent with their origin
Distinguishing class of leukemia and lymphoma
use of immunohistochemistry
Immunohistochemistry for tissue-specific or organ-specific antigens
determines origin or metastatic tumor
Tumor cells expressing cytokeratins
epithelial origin
Tumor cells expressing desmin
muscle origin
Immunohistochemistry can distinguish between subtypes of cancer (ER-positive, ER-negative, capthesin D) relies on
overexpression of proteins within the cells
Importance of distinguishing subtypes in cancer
determining susceptibility to therapy
ER-positive therapy
ER expression; responsive to tamoxifen
Tamoxifen action
binds ER, cannot bind coactivators
ER-negative therapy
no ER expression; responsive to Herceptin
Herceptin action
cancer overexpresses ERBB-> HER2/neu protein; Herceptin binds and inactivates the cell surface GFR
Cathepsin-D breast cancer
rapid development of metastases (metastatic potential)
FC
gives information about physical and chemical structure of each cell
FSC =
cell volume
SSC =
shape of nucleus, cytoplasmic granule types, membrane roughness
Fluorescence in FC
presence (relative quantity) or antigen on surface
FC used to
classify leukemia and lymphoma, detection of ploidy
aneuploidy is associated with
poorer prognosis for cancer patient
Primary modality for cancer diagnosis
histology
FISH
used to differentiate B and T cell malignancies, by detection of specific translocations that activate oncogenes
FISH procedure
DNA probe for specific sequence + sample + fluorophores –> reveals translocations and other chromosomal rearrangements
Array based comparative Hybridization
examine the molecular profile (quantify the expression of large numbers of genes) of different tumors using mRNA levels -> gives clues of potential over expression of tumor markers
Array based comparative Hybridization complications
uses mRNA which do not directly correspond with proteins; this is due to rate of translation, protein breakdown, and protein export
Complications of using tumor markers
low specificity/sensitivity, used as supporting evidence
Carcinoembryonic antigen (CEA)
glycoprotein produced in embryonic tissues of the digestive tract, pancreas, and liver; may be elevated in colorectal and pancreatic carcinoma
CEA tumor marker use
because it is also elevated in certain non-malignant disease, there is LOW specificity and sensitivity; but may be useful as a prognostic indicator (CEA increased with tumor size)
Alpha fetal protein
glycoprotein produced early in fetal life by the yolk sac, liver, and GI tract; may be elevated in hepatocellular carcinoma and germ cells of the testis
PSA
prostate specific membrane antigen used as a marker for prostate cancer
HCG
testicular tumor marker
CA125
tumor marker for ovarian tumors
Main factors for prognosis and therapy
tumor size, metastases
