PATHOLOGY Flashcards
Reversible cell injury
- Decrease ATP –> decrease activity of Ca2+ and Na+/K+ pumps –> cellular swelling (earliest morphologic manifestation), mitochondrial swelling
- Ribosomal/polysomal detachment –> decrease protein synthesis
- Plasma membrane changes (eg, blebbing)
- Nuclear changes (eg, chromatin clumping)
- Rapid loss of function (eg, myocardial cells are noncontractile after 1-2 minutes of ischemia)
- Myelin figures (aggregation of peroxidized lipids)
Irreversible cell injury
- Breakdown of plasma membrane –> cytosolic enzymes (eg, troponin) leak outside of cell, influx of Ca2+ –> activation of degradative enzymes
- Mitochondrial damage/dysfunction –> loss of electron transport chain –> decrease ATP
- Rupture of lysosomes –> autolysis
- Nuclear degradation –> pyknosis (nuclear condensation) –> karyorrhexis (nuclear fragmentation caused by endonuclease-mediated cleavage) –> karyolysis (nuclear dissolution)
- Amorphous densities/inclusions in mitochondria
Red (hemorrhagic) Infarct
- Occurs in venous occlusion and tissues with multiple blood supplies (eg, liver, lungs, intestine, testes), and with reperfusion (eg, after angioplasty).
- Reperfusion injury is due to damage by free radicals.
Pale (anemic) Infarct
Occurs in solid organs with a single (end- arterial) blood supply (eg, heart, kidney, spleen).
TGF-β
Angiogenesis
Fibrosis
FGF
Stimulates angiogenesis
VEGF
Stimulates angiogenesis
PDGF
- Secreted by activated platelets and macrophages
- Induces vascular remodeling and smooth muscle cell migration
- Stimulates fibroblast growth for collagen synthesis
Metalloproteinases
Tissue remodeling
EGF
Stimulates cell growth via tyrosine kinases (eg, EGFR/ErbB1)
Brain Metastases Primary Tumor
Lung > breast > melanoma, colon, kidney
Lots of Brain Metastases Can Kill
Bone Metastases Primary Tumor
Prostate, breast > kidney, thyroid, lung
Painful Bones Kill The Lungs
Liver Metastases Primary Tumor
Colon >> stomach > pancreas
Cancer Sometimes Penetrates liver
Mention Oncogenes
ALK
BCR-ABL
BCL-2
BRAF
c-KIT
c-MYC
CDK4
CCND1
ERBB1
HER2/neu (c-erbB2)
JAK2
KRAS
MYCL1 (L-myc-1)
N-myc (MYCN)
RET
Mention Tumor Suppressors
APC
BRCA1/BRCA2
CDKN2A
DCC
SMAD4 (DPC4)
MEN1
NF1
NF2
PTEN
RB1
TP53
TSC1
TSC2
VHL
WT1
WT2
ALK
Oncogene (chromosome 2)
- Receptor tyrosine kinase
- Associated with lung adenocarcinoma
BCR-ABL
- Oncogene
- Non-receptor tyrosine kinase
- Associated with CML, ALL
BCL-2
- Oncogene (chromosome 18)
- Antiapoptotic molecule
- Associated with follicular lymphoma, diffuse large B cell lymphoma
BRAF
- Oncogene (chromosome 7q34)
- Serine/threonine kinase
- Associated with melanoma, non-Hodgkin lymphoma, papillary thyroid carcinoma, hairy cell leukemia
c-KIT
- Oncogene (chromosome 4q12)
- Cytokine receptor
- Associated with gastrointestinal stromal tumors, mastocytosis
c-MYC
Oncogene (chromosome 8) Transcription factor Associated with Burkitt lymphoma
CDK4
Oncogene (chromosome 12) Cyclin-dependent kinase Associated with liposarcoma, melanoma, glioblastoma multiforme
CCND1
Oncogene (chromosome 11) Cyclin D (regulatory protein of the cell cycle) Associated with mantle cell lymphoma
ERBB1
Oncogene (chromosome 7) Epidermal growth factor receptor (EGFR) Associated with non-small cell lung cancer
HER2/neu (c-erbB2)
Oncogene (chromosome 17q12) Receptor tyrosine kinase Associated with breast cancer, gastric cancer
JAK2
Oncogene (chromosome 9p24) Non-receptor tyrosine kinase Associated with chronic myeloproliferative disorders
KRAS
Oncogene (chromosome 12) GTPase Associated with colorectal cancer, lung cancer, pancreatic cancer
MYCL1 (L-myc-1)
Oncogene (chromosome 1) Transcription factor Associated with lung cancer
N-myc (MYCN)
Oncogene (chromosome 2) Transcription factor Associated with neuroblastoma
RET
Oncogene (chromosome 10) Receptor tyrosine kinase Associated with papillary thyroid cancer, pheochromocytoma, MEN 2A and MEN 2B
APC
Tumor Suppressor (chromosome 5) A protein that prevents unregulated cell proliferation by inhibiting β-catenin synthesis → inhibition of the β-catenin/Wnt pathway (β-catenin is involved in the Wnt pathway, which stimulates cell proliferation) Associated with familial adenomatous polyposis (associated with colorectal cancer), sporadic colorectal cancer
BRCA1
Tumor Suppressor (chromosome 17) DNA repair protein Associated with breast cancer, ovarian cancer, pancreatic cancer
CDKN2A
Tumor Suppressor (chromosome 9) p16 protein, which normally causes cell cycle arrest at the G1 phase Associated with melanoma, pancreatic cancer, lung cancer
DCC
Tumor Suppressor (chromosome 18) Transmembrane receptor involved in cell apoptosis Associated with colorectal cancer
SMAD4 (DPC4)
Tumor Suppressor (chromosome 18) A DNA binding protein involved in signal transduction from TGF-β receptors Associated with pancreatic cancer
MEN1
Tumor Suppressor (chromosome ) Associated with
NF1
Tumor Suppressor (chromosome 17) Neurofibromin (Ras GTPase-activating protein) Associated with neurofibromatosis type 1
NF2
Tumor Suppressor (chromosome 22) Merlin (schwannomin) Associated with neurofibromatosis type 2
PTEN
Tumor Suppressor (chromosome 10) Negatively regulates the PI3k/AKT pathway Associated with prostate cancer, endometrial cancer, breast cancer, Cowden syndrome
RB1
Tumor Suppressor (chromosome 13) Causes cell cycle arrest at the G1 phase by inhibiting E2F transcription factor Associated with retinoblastoma, osteosarcoma
TP53
Tumor Suppressor (chromosome 17) Causes cell apoptosis Activates proapoptotic genes (e.g., BAX) Causes cell cycle arrest at the G1 phase (by activating p21) Inhibits entry in the S phase via inhibition of pRb phosphorylation Associated with most human cancers, Li-Fraumeni syndrome
TSC1
Tumor Suppressor (chromosome 9) Hamartin protein Associated with tuberous sclerosis
TSC2
Tumor Suppressor (chromosome 16) Tuberin protein Associated with tuberous sclerosis
VHL
Tumor Suppressor (chromosome 3) Protein involved in the degradation of hypoxia-inducible factor 1a Associated with Von Hippel Lindau disease
WT1
Tumor Suppressor (chromosome 11) Transcription factor that regulates urogenital development Associated with nephroblastoma (Wilms tumor)
WT2
Tumor Suppressor (chromosome 11) Transcription factor that regulates urogenital development Associated with nephroblastoma (Wilms tumor)
BRCA2
Tumor Suppressor (chromosome 13) DNA repair protein Associated with breast cancer, ovarian cancer, pancreatic cancer
Benzene Carcinogen
Ocurrece: Gasoline Cigarette smoke Associated malignancy: Acute leukemia Non-Hodgkin lymphoma
Nitrosamines Carcinogen
Occurrence: Cured meats (e.g. bacon) and fish Cold-smoked foods (the major carcinogens produced during the smoking process (both cold and hot) are the polycyclic aromatic hydrocarbons, chemicals that are formed during the burning of solid fuels (e.g., wood, coal)) Tobacco Associated malignancy: Gastric cancer
Vinyl chloride Carcinogen
Occurrence: Production of polyvinyl chloride (PVC) and PVC-related manufacturing (e.g., of PVC pipes, cables) Associated malignancy: Lung cancer Hepatocellular carcinoma Glioblastoma Angiosarcoma
Aromatic amines (β-naphthylamine, benzidine) Carcinogen
Occurrence: Tobacco smoke Dyes (occupational exposure in the textile industry) Rubber Associated malignancy: Bladder cancer (transitional cell carcinoma)
Asbestos Carcinogen
Occurrence: Insulation material (formerly used in construction and shipbuilding) Asbestos cement (fibrolite), roofing, and siding Associated malignancy: Lung cancer (bronchogenic carcinoma) Mesothelioma The risk of developing bronchogenic carcinoma is greater than that of developing mesothelioma.
Wood dust Carcinogen
Occurrence: Woodworking (e.g., sawing, drilling, sanding) Associated malignancy: Adenocarcinoma of the nose and paranasal sinuses
Ethanol Carcinogen
Occurrence: Alcoholic beverages Associated malignancy: Squamous cell carcinoma of the esophagus Hepatocellular carcinoma (HCC) Breast cancer
Alkylating agents Carcinogen
Occurrence: Chemotherapeutic agents (e.g., cyclophosphamide, melphalan, busulfan, carmustine) Associated malignancy: Leukemia Lymphoma
Cigarette smoke Carcinogen
Occurrence: First-hand smoke (smoke inhaled by the smoker) Second-hand smoke (exhaled smoke that is inhaled by others in the vicinity of the smoker) Third-hand smoke (smoke particles that adhere to surfaces in the surroundings of the smoker) All three have been proven to be carcinogenic. Associated malignancy: Transitional cell carcinoma of the bladder Squamous cell carcinoma (cervix, oropharynx, esophagus, larynx, lung) Small cell lung cancer Pancreatic adenocarcinoma Adenocarcinoma of the esophagus Renal cell carcinoma
Radon Carcinogen
Occurrence: Accumulates in basements (a byproduct of uranium decay) Uranium is found in soil. The natural radioactive decay of uranium produces radon. Radon can accumulate in basements that are in direct contact with soil. Associated malignancy: Lung cancer (radon is the second most common cause following exposure to cigarette smoke)
Aflatoxin Carcinogen
Occurrence: Stored nuts and grains (Aspergillus flavus growth) Associated malignancy: HCC
Arsenic Carcinogen
Occurrence: Contaminated groundwater (esp. in developing countries) Pesticides, herbicides (e.g., vineyard workers) Metal smelting Associated malignancy: Lung cancer Squamous cell carcinoma Hepatic angiosarcomas
Beryllium Carcinogen
Occurrence: Occupations that involve beryllium production and processing (esp. melting and founding, welding manufacturing [industrial ceramics, electronics, automotive, aerospace, and defense components, dental supplies and prostheses]) Associated malignancy: Lung cancer
Silica Carcinogen
Occurrence: Occupations that involve cutting, drilling, chipping, or grinding crystalline silica (e.g., quartz) or materials that contain it (e.g., sand, granite), esp. sandblasting, glass manufacturing, construction work Associated malignancy: Lung cancer
Chromium
Occurrence: Significant in workers exposed to galvanization (chrome plating), paint and glass manufacturing, tanning leather, building materials Associated malignancy: Lung cancer
Nickel
Occurrence: Occupations that involve mining, smelting, welding, and casting of alloys (e.g., in coins, jewelry) Associated malignancy: Lung cancer
Nonionizing radiation
Occurrence: UV-B Associated malignancy: Skin cancers
Ionizing radiation
Occurrence: X-rays Gamma rays Associated malignancy: Leukemias (especially AML and CML) Papillary thyroid cancer Osteosarcoma Liver angiosarcoma
Apoptosis Histopathological Findings
- Shrunken and irregularly shaped cells with condensed chromatin and membrane blebbing - The cell detaches from other cells or the extracellular matrix. - The basophilic nucleus undergoes the following changes: 1. Pyknosis 2. Kareyorrhexis 3. Karyolysis - The eosinophilic cytoplasm and cell organelles form small bubbles and the endonucleases degrade the chromatin in the nucleus, resulting in nuclear fragmentation and apoptotic bodies that are phagocytized by macrophages. - DNA laddering (fragments in multiples of 180 base pairs) is seen on gel electrophoresis and can be used as a sensitive marker for apoptosis.
Coagulative Necrosis
Seen in: Ischemia/infarcts in most tissues (except brain) Myocardial, splenic, hepatic, and renal infarction Gangrene Organ damage caused by acidic solutions Due to: Ischemia or infarction; injury denatures enzymes –> proteolysis blocked Decreased oxygen delivery → ↓ ATP -Anaerobic metabolism → ↑ lactic acid production → ↓ pH → denaturation of proteins (including proteolytic enzymes) → cell death -Impaired Na+/K+-ATPase → ↑ intracellular Na+ → ↑ intracellular H2O → cell swelling Histology: Preserved cellular architecture (cell outlines seen) due to denaturation of lytic enzymes and disrupted proteolysis Cells become anucleated with eosinophilic cytoplasm Leukocytes eventually infiltrate necrotic tissue and digest cellular debris Increase cytoplasmic binding of eosin stain (–> increase eosinophilia; red/pink color)
Liquefactive Necrosis
Seen in: Focal bacterial infections that stimulate massive leukocyte recruitment, bacterial abscesses (purulent infection), brain infarcts due to lack of substantive supporting stroma, pancreatitis (due to enzymatic damage to the parenchyma), organ damage caused by alkaline solutions Due to: Neutrophils release lysosomal enzymes that digest the tissue forming a viscous liquid mass. Necrotic fluid is often creamy yellow due to presence of dead leukocytes (pu) Tissue softening → fluid necrosis → cavitation, pseudocyst formation Histology: Early → cellular debris and macrophages Late → cystic spaces and cavitation (brain) Neutrophils and cell debris seen with bacterial infection Brain infarcts eventually resolve into CSF-filled spaces
Caseous Necrosis
Seen in: TB, systemic fungi (eg, Histoplasma capsulatum, Coccidioides, Cryptococcus), Nocardia Due to: Macrophages, epitheloid cells, and multinucleated giant cells (Langhans giant cell) surround a site of infection → granular debris Histology: Fragmented cells and debris, surrounded by lymphocytes, epitheloid cells, and multinucleated giant cells, forming a granuloma Necrotic tissue has a cheesy tan-white gross appearance and consist of fragmented cells and acellular proteinaceous material
Fat Necrosis
Seen in: Enzymatic: acute pancreatitis (saponification of peripancreatic fat) Nonenzymatic: traumatic (eg, injury to breast tissue) Due to: A type of necrosis in which adipose cells die off prematurely, either caused by an enzymatic reaction, or traumatic injury. Enzymatic fat necrosis (release of lipase and triglycerides from cytoplasm of damaged cells → breakdown of triglycerides by lipase → binding of fatty acids to calcium → saponification → chalky-white appearance) Infiltrating foamy macrophages containing engulfed lipid debris and release of free fatty acids that combine with calcium to form basophilic deposits. Histology: Outlines of adipocytes with no peripheral nuclei Combination of fat saponification and calcium → dark blue appearance on H&E stain
Fibrinoid Necrosis
Seen in: Rheumatoid arthritis Peptic ulcer disease Immune vasculitis (e.g., polyarteritis nodosa) Vascular reactions Preeclampsia Hypertensive emergency Due to: Vessel wall damage caused by immune complex deposition (e.g., due to type III hypersensitivity reaction) → fragmentation of collagenous and elastic fibers → leakage of fibrin and other plasma proteins Histology: Vessel walls are thick and pink Visible damage → thick walls with fragments of embedded cellular debris, serum, and fibrin Affected necrotic areas stain intense red.