All the high yield facts from general pathology that are usually asked in examsUSMLE STEP 1, Medical Council exams.
Reversible Cell Injury |
• swelling of cell organelles and entire cell • dissociation of ribosomes from endoplasmic reticulum • decreased energy production by mitochondria • increased glycolysis → decreased pH → nuclear chromatin clumping |
Irreversible Cell Injury |
• dense bodies within mitochondria (flocculent densities in heart) • release of cellular enzymes (e.g., SGOT, LDH, and CPK after MI) • nuclear degeneration (pyknosis, karyolysis, karyorrhexis) • cell death |
Irreversible Cell Injury |
• dense bodies within mitochondria (flocculent densities in heart) • release of cellular enzymes (e.g., SGOT, LDH, and CPK after MI) • nuclear degeneration (pyknosis, karyolysis, karyorrhexis) • cell death |
FATTY CHANGE OF THE LIVER |
1. Increased delivery of free fatty acids to liver • starvation • corticosteroids • diabetes mellitus 2. Increased formation of triglycerides • alcohol (note: NADH > NAD) 3. Decreased formation of apoproteins • carbon tetrachloride • protein malnutrition (kwashiorkor) |
Apoptosis |
• “programmed” cell death • single cells (not large groups of cells) • cells shrink → form apoptotic bodies • gene activation → forms endonucleases • peripheral condensation of chromatin with DNA ladder • no inflammatory response Examples of apoptosis: 1. Physiologic • involution of thymus • cell death within germinal centers of lymph nodes • fragmentation of endometrium during menses • lactating breast during weaning 2. Pathologic • viral hepatitis • cytotoxic T cell–mediated immune destruction (type IV hypersensitivity) |
Necrosis |
• cause → hypoxia or toxins (irreversible injury) • many cells or clusters of cells • cells swell • inflammation present Examples of necrosis: • coagulative necrosis → ischemia (except the brain) • liquefactive necrosis → bacterial infection (and brain infarction) • fat necrosis → pancreatitis and trauma to the breast • caseous necrosis → tuberculosis • fibrinoid necrosis →autoimmune disease (type III hypersensitivity reaction) • gangrene →ischemia to extremities →dry (mainly coagulative necrosis) or wet (mainly liquefactive necrosis due to bacterial infection) |
Adaptation |
• hypertrophy → increase in the size of cells • hyperplasia → increase in the number of cells • atrophy → decrease in the size of an organ • aplasia → failure of cell production • hypoplasia → decrease in the number of cells • metaplasia → replacement of one cell type by another • dysplasia → abnormal cell growth |
Abnormal Organ Development |
• agenesis → complete failure of an organ to develop (no anlage present) • hypoplasia → reduction in the size of an organ due to a decrease in the number of cells • atrophy →decrease in the size of an organ due to a decrease in the number of preexisting cells |
CARDINAL SIGNS OF INFLAMMATION |
• rubor → red • calor → hot • tumor → swollen • dolor → pain |
COMPLEMENT CASCADE |
• C3b → opsonin • C5a → chemotaxis and leukocyte activation • C3a, C4a, C5a → anaphylatoxins • C5–9 → membrane attack complex Deficiencies • deficiency of C3 and C5 → recurrent pyogenic bacterial infections • deficiency of C6, C7, and C8 →recurrent infections with Neisseria species • deficiency of C1 esterase inhibitor → hereditary angioedema • deficiency of decay-accelerating factor → paroxysmal nocturnal hemoglobinuria |
THROMBOXANE VS. PROSTACYCLIN |
Thromboxane • produced by platelets • causes vasoconstriction • stimulates platelet aggregation Prostacyclin • produced by endothelial cells • causes vasodilation • inhibits platelet aggregation |
GRANULOMATOUS INFLAMMATION |
Caseating Granulomas • aggregates of activated macrophages (epitheloid cells) • tuberculosis Noncaseating Granulomas • sarcoidosis • fungal infections • foreign-body reaction |
COLLAGEN TYPES |
Fibrillar Collagens • type I → skin, bones, tendons, mature scars • type II → cartilage • type III → embryonic tissue, blood vessels, pliable organs, immature scars Amorphous Collagens • type IV → basement membranes • type VI → connective tissue |
Exudates |
1. Composition • increased protein • increased cells • specific gravity greater than 1.020 2. Cause • inflammation • increased blood vessel permeability |
Transudates |
1. Composition • no increased protein • no increased cells • specific gravity less than 1.012 2. Cause → abnormality of Starling forces a. increased hydrostatic (venous) pressure • congestive heart failure • portal hypertension b. decreased oncotic pressure → due to decreased albumin • liver disease • renal disease (nephrotic syndrome) c. lymphatic obstruction • tumors or surgery • filaria |
NEOPLASMS |
Benign • grow slowly • remain localized • may have well-developed fibrous capsule • do not metastasize • well differentiated histologically Malignant • grow rapidly • locally invasive • irregular growth; no capsule • capable of metastasis • variable degrees of differentiation (well differentiated, moderately differentiated, poorly differentiated) |
ONCOGENE EXPRESSION |
Growth Factors 1. c-sis • β chain of platelet-derived growth factor • astrocytomas and osteogenic sarcomas Growth Factor Receptors 1. c-erb B1 • receptor for epidermal growth factor • breast cancer and squamous cell carcinoma of the lung 2. c-neu • receptor for epidermal growth factor • breast cancer 3. c-fms • receptor for colony-stimulating factor (CSF) • leukemia Abnormal Membrane Protein Kinase 1. c-abl • membrane tyrosine kinase • chronic myelocytic leukemia (CML) GTP-Binding Proteins 1. c-ras • product is p21 (protein) • adenocarcinomas Nuclear Regulatory Proteins 1. c-myc → Burkitt’s lymphoma 2. N-myc → neuroblastoma 3. L-myc → small cell carcinoma of the lung 4. c-jun 5. c-fos |
CHROMOSOMES AND CANCER |
Point Mutations • c-ras → adenocarcinomas Translocations • c-abl on chromosome 9 → CML • c-myc on chromosome 8 → Burkitt’s lymphoma • bcl-2 on chromosome 18 → nodular lymphoma Gene Amplification • N-myc → neuroblastoma • c-neu → breast cancer • c-erb B2 → breast cancer |
ANTIONCOGENES |
Tumor Suppressor Genes • Rb → retinoblastoma and osteogenic sarcoma • p53 → many tumors and the Li-Fraumeni syndrome • WT1 → Wilms’ tumor and aniridia • NF1 → neurofibromatosis type 1 |
CHEMICAL CARCINOGENS |
Initiators • tobacco smoke → many tumors • benzene → leukemias • vinyl chloride → angiosarcomas of the liver • β-naphthylamine → cancer of the urinary bladder • azo dyes → tumors of the liver • aflatoxin → hepatoma • asbestos → mesotheliomas and lung tumors • arsenic → skin cancer Promoters • saccharin → bladder cancer in rats • hormones (estrogen) |
VIRUSES AND CANCER |
RNA Viruses • acute-transforming viruses • slow-transforming viruses • HTLV-1 → adult T cell leukemia/lymphoma DNA Viruses 1. HPV (different subtypes) • cervical neoplasia • condyloma • verruca vulgaris 2. EBV • African Burkitt’s lymphoma • carcinoma of the nasopharynx • B cell immunoblastic lymphoma 3. Hepatitis B and hepatitis C • liver cancer |
PARANEOPLASTIC SYNDROMES |
• Cushing’s syndrome (increased cortisol) → lung cancer • carcinoid syndrome (increased serotonin) → lung cancer or carcinoid tumor of the small intestine • syndrome of inappropriate ADH secretion (SIADH) → lung cancer and intracranial neoplasms • hypercalcemia → lung cancer or multiple myeloma • hypocalcemia → medullary carcinoma of the thyroid (secretes procalcitonin; stains as amyloid) • hypoglycemia → liver cancer and tumors of the mesothelium (mesotheliomas) • polycythemia (erythropoietin) →kidney tumors, liver tumors, and cerebellar vascular tumors |
TUMOR MARKERS |
b-HCG (Human Chorionic Gonadodotropin) • gestational trophoblastic disease (e.g., choriocarcinoma, hydatidiform mole) • dysgerminoma • seminoma (10% of cases) a-Fetoprotein (AFP) • liver cancer • germ cell tumors (e.g., yolk sac tumors, embryonal carcinoma, NOT seminoma) Prostate-Specific Antigen (PSA) and Prostatic Acid Phosphatase (PAP) • adenocarcinoma of prostate Carcinoembryonic Antigen (CEA) • adenocarcinomas of colon, pancreas, stomach, and breast (nonspecific marker) CA-125 • ovarian cancer S-100 • melanoma • neural tumors |
PROTEIN-ENERGY MALNUTRITION (PEM) |
Kwashiorkor • dietary protein deficiency (without calorie deficiency) • anasarca (generalized edema) • fatty liver (due to decreased apoproteins and decreased VLDL synthesis) • abnormal skin and hair • defective enzyme formation → malabsorption (hard to treat) Marasmus • dietary calorie deficiency (without protein deficiency) • generalized wasting (“skin and bones”) |
NUTRITIONAL DEFICIENCIES |
Vitamin A • night blindness • dry eyes and dry skin • recurrent infections Vitamin D • decreased calcium • bone → decreased calcification, increased osteoid • children → rickets • adults → osteomalacia Vitamin E • degeneration of posterior columns of spinal cord Vitamin K • decreased vitamin K–dependent factors → II, VII, IX, X, and proteins C and S • increased bleeding • increased PT and PTT Vitamin B1 (Thiamine) • beriberi → wet (cardiac) or dry (neurologic) • Wernicke-Korsakoff syndrome (lesions of mamillary bodies) Vitamin B3 (Niacin) • pellagra → 3Ds = dermatitis, dementia, diarrhea (and death) Vitamin B12 (Cobalamin) • megaloblastic (macrocytic) anemia • hypersegmented neutrophils (> 5 lobes) • subacute combined degeneration of the spinal cord Vitamin C (Ascorbic Acid) • scurvy • defective collagen formation → poor wound healing (wounds reopen) • bone → decreased osteoid • perifollicular hemorrhages (“corkscrew” hair) • bleeding gums and loose teeth Folate • megaloblastic (macrocytic) anemia • hypersegmented neutrophils • associated with neural tube defects in utero Iron • microcytic hypochromic anemia (with increased TIBC) |
INHERITANCE PATTERNS |
Autosomal Dominant (AD) • disease produced in heterozygous state • no skipped generations → parents affected (unless new mutation or reduced penetrance) • father-to-son transmission possible • males and females affected equally • recurrence risk is 50% Autosomal Recessive (AR) • disease produced in homozygous state • heterozygous individuals are carriers • skipped generations • father-to-son transmission possible • males and females affected equally • recurrence risk is 25% X-Linked Dominant (XD) • no skipped generations • no male-to-male transmission • females affected twice as often as males X-Linked Recessive (XR) • skipped generations • no male-to-male transmission • males affected more frequently than females Y Inheritance • only males affected • only male-to-male transmission • all males affected Mitochondrial • males and females affected • only females transmit the disease |
EXAMPLES OF XR |
Hematology Diseases • glucose-6-phosphate dehydrogenase (G6PD) deficiency • hemophilia A (deficiency of factor VIII) • hemophilia B (deficiency of factor IX) Immunodeficiency Diseases • Bruton’s agammaglobulinemia • chronic granulomatous disease • Wiskott-Aldrich syndrome Storage Diseases • Fabry’s disease • Hunter’s syndrome Muscle Diseases 1. Duchenne muscular dystrophy • defective dystrophin gene (muscle breakdown) • pseudohypertrophy of calf muscles • Gower maneuver (using hands to rise from floor) 2. Becker muscular dystrophy Metabolic Diseases • diabetes insipidus • Lesch-Nyhan syndrome Other Diseases • red-green color blindness • fragile X syndrome |
AUTOSOMAL TRISOMIES |
Trisomy 13 (Patau’s Syndrome) • mental retardation • microcephaly and microphthalmia • holoprosencephaly (fused forebrain) • fused central face (“cyclops”) • cleft lip and palate • heart defects Trisomy 18 (Edwards’ Syndrome) • mental retardation • micrognathia • heart defects • rocker-bottom feet • clenched fist with overlapping fingers Trisomy 21 (Down’s Syndrome) • most cases due to maternal nondisjunction during meiosis I (associated with increased maternal age) • minority of cases due to Robertsonian (balanced) translocation • mental retardation (most common familial cause) • oblique palpebral fissures with epicanthal folds • horizontal palmar crease • heart defects (endocardial cushion defect is most common) • acute lymphoblastic leukemia (first 2 years of life) • Alzheimer’s disease (almost 100% incidence after age 35) • duodenal atresia (“double-bubble” sign on x-ray) |
CHROMOSOMAL DELETIONS |
5p- (Cri du Chat) • high-pitched cry • mental retardation • heart defects and microcephaly 11p- • Wilms tumor • absence of iris 13q- • retinoblastoma 15q- 1. Maternal deletion → Angelman’s syndrome • stiff, ataxic gait with jerky movements • inappropriate laughter (“happy puppets”) • may be due to two copies of paternal 15 chromosome (paternal uniparental disomy) 2. Paternal deletion → Prader-Willi syndrome • mental retardation • short stature and obesity • small hands and feet • hypogonadism • may be due to two copies of maternal 15 chromosome (paternal uniparental disomy) |
HYPOGONADISM |
Klinefelter’s Syndrome • most common genotype is 47,XXY • male hypogonadism • testicular dysgenesis → small, firm, atrophic testes • decreased testosterone • increased FSH, LH, estradiol • decreased secondary male characteristics • tallness, gynecomastia, and female distribution of hair • infertility Turner’s Syndrome • most common genotype is 45,XO • female hypogonadism • ovarian dysgenesis → streak ovaries • decreased estrogen • increased LH, FSH • primary amenorrhea • decreased secondary female characteristics • skeletal abnormalities → short stature • web neck (cystic hygroma) |
AMBIGUOUS SEXUAL DEVELOPMENT |
True Hermaphrodite • ovaries and testes both present Female Pseudohermaphrodite (XX Individual) • ovaries • male or ambiguous external genitalia • due to excess androgens (e.g., congenital adrenal hyperplasia) Male Pseudohermaphrodite (XY Individual) • testes • female external genitalia • due to decreased androgen effects (most common →testicular feminization) Androgen Insensitivity Syndrome (XY Individual) • testicular feminization • Müllerian duct regression (due to MIF) • Wolffian duct regression (due to lack of testosterone receptors) • phenotypic female (due to lack of receptors for DHT) Decreased 5-a-Reductase (XY Individual) • formation of testes (due to presence of Y chromosome) • Müllerian duct regression (due to MIF) • Wolffian duct development (due to testosterone) • decreased DHT (due to lack of 5-α-reductase) • variable external genitalia (due to decreased DHT) Turner’s Syndrome (XO Individual) • streak gonads (due to lack of two X chromosomes) • Müllerian duct development (due to lack of MIF) • Wolffian duct regression (due to lack of testosterone) • external female (due to lack of DHT) • decreased secondary female characteristics (due to decreased estrogen) Congenital Adrenal Hyperplasia (XX Individual) • development of ovaries (due to two X chromosomes) • Müllerian duct development (due to lack of MIF) • Wolffian duct regression (due to lack of local testosterone production) • external male (due to excess systemic formation of DHT) |
B Cells |
• form plasma cells that secrete immunoglobulin • surface antigen receptor composed of immunoglobulin • rearrange immunoglobulin genes from germ line configuration • CD19 → pan–B cell marker • CD20 → pan–B cell marker, also called L26 • CD21 → pan–B cell marker, receptor for EBV • CD22 → pan–B cell marker |
T Cells |
• secrete lymphokines • surface antigen receptor (TCR) is attached to CD3 • rearrange genes for T cell receptor • CD2 → receptor for sheep erythrocyte (E rosette) • CD3 → attached to T cell receptor • CD4 → helper T cells, bind with MHC class II antigens • CD5 → pan–T cell marker • CD7 → pan–T cell marker • CD8 → cytotoxic T cells, bind with MHC class I antigens |
Natural Killer Cells |
• large granular lymphocytes • do not need previous sensitization • CD16 → receptor for Fc portion of IgG |
IgM |
• large molecule (pentamer) • secreted early in immune response (primary response) • cannot cross the placenta • can activate complement • contains a J chain |
IgG |
• most abundant immunoglobulin in serum • secreted during second antigen exposure (secondary or amnestic response) • can cross the placenta • can activate complement • can function as opsonin |
IgE |
• allergies, asthma, parasitic infection • found attached to the surface of basophils and mast cells • participates in type I hypersensitivity reactions |
IgA |
• usually a dimer with a J chain and a secretory component • found along GI tract and respiratory tract • secretory immunoglobulin • can activate alternate complement pathway |
CD4+ Cells |
• helper T lymphocytes • respond to MHC class II antigens Subtypes: 1. T helper-1 (TH1) cells • secrete → IL-2, IL-3, GM-CSF, γ-interferon, and lymphotoxin (β-TNF) • stimulate cell-mediated immune reactions → fight intracellular organisms 2. T helper-2 (TH2) cells • secrete → IL-3, IL-4, IL-5, IL-6, IL-10, and GM-CSF • stimulate antibody production → fight extracellular organisms |
CD8+ Cells |
• cytotoxic T lymphocytes • respond to MHC class I antigens |
MAJOR HISTOCOMPATIBILITY COMPLEX (MHC) |
Class I Antigens • found on all nucleated cells • transmembrane α glycoprotein chain with β2-microglobulin • react with antibodies and CD8-positive lymphocytes • fight virus-infected cells and transplants Class II Antigens • found on antigen-presenting cells, B cells, and T cells • transmembrane α chain and β chain • react with CD4-positive lymphocytes • fight exogenous antigens that have been processed by antigen-presenting cells |
DISEASES ASSOCIATED WITH HLA TYPES |
• ankylosing spondylitis → HLA-B27 • primary hemochromatosis → HLA-A3 • 21-hydroxylase deficiency → HLA-BW47 • rheumatoid arthritis → HLA-DR4 • insulin-dependent (type I) diabetes mellitus → HLA-DR3/DR4 • systemic lupus erythematosus → HLA-DR2/DR3 |
HYPERSENSITIVITY REACTIONS |
Type I • binding of antigen to previously formed IgE bound to mast cells and basophils • release of histamine and leukotrienes C4 and D4 • urticaria (hives) • anaphylaxis Type II • antibody (IgG or IgM) binds to antigens in situ • cells destroyed by complement or cytotoxic cells (antibody-dependent cell-mediated cytotoxicity) • linear immunofluorescence (IF) • transfusion reactions Type III • antibody (IgG or IgM) binds to antigens forming immune complexes • granular IF • systemic → serum sickness • local reaction → Arthus reaction Type IV 1. Delayed type hypersensitivity • CD4 lymphocytes • extrinsic antigen associated with class II MHC • formation of activated macrophages (epitheloid cells) →granulomas • PPD skin test • contact dermatitis (poison ivy, poison oak) 2. Cell-mediated immunity • CD8 lymphocytes • intrinsic antigen associated with class I MHC • viral infections and transplant rejection |
AUTOANTIBODIES |
Nuclear • diffuse (homogenous) → DNA (many diseases), histones (drug-induced SLE) • rim (peripheral) → double-stranded DNA (SLE) • speckled (non-DNA extractable nuclear proteins) → Smith (SLE), SS-A and SS-B (Sjögren’s syndrome), Scl-70 (progressive systemic sclerosis) • nucleolar (RNA) → many (e.g., progressive systemic sclerosis) • centromere → CREST syndrome Cytoplasmic • mitochondria → primary biliary cirrhosis Cells • smooth muscle →lupoid hepatitis (autoimmune chronic active hepatitis) • neutrophils → Wegener’s granulomatosis and microscopic polyarteritis • parietal cell and intrinsic factor → pernicious anemia • microvasculature of muscle → dermatomyositis Proteins • immunoglobulin → rheumatoid arthritis • thyroglobulin → Hashimoto’s thyroiditis Structural Antigens • lung and glomerular basement membranes → Goodpasture’s disease • intercellular space of epidermis → pemphigus vulgaris • epidermal basement membrane → bullous pemphigoid Receptors • acetylcholine receptor → myasthenia gravis • thyroid hormone receptor → Graves’ disease • insulin receptor → diabetes mellitus |
ANTINEUTROPHIL CYTOPLASMIC ANTIBODIES (ANCAs) |
1. C-ANCAs (cytoplasmic) • proteinase 3 → Wegener’s granulomatosis 2. P-ANCAs (perinuclear) • myeloperoxidase → microscopic polyarteritis |
AMYLOIDOSIS |
Amyloid • any protein having β-pleated sheet tertiary configuration • apple-green birefringence with Congo red stain Systemic Deposition • multiple myeloma → deposits of amyloid light protein • chronic inflammatory diseases → deposits of amyloid-associated protein • hemodialysis → deposits of β2-microglobulin Localized Deposition • senile cardiac disease → deposits of amyloid transthyretin • Alzheimer’s disease → deposits of β2-amyloid protein • medullary carcinoma of thyroid → deposits of procalcitonin • non-insulin-dependent diabetes mellitus (type II) →amyloid deposits in islets of Langerhans of pancreas |
Chédiak-Higashi Syndrome |
• autosomal recessive |
FAMILIAL HYPERLIPIDEMIA |
Type I Hyperlipoproteinemia • familial hyperchylomicronemia • mutation in lipoprotein lipase gene • increased serum chylomicrons Type II Hyperlipoproteinemia • familial hypercholesterolemia • mutation involving LDL receptor • increased serum LDL • increased serum cholesterol Type III Hyperlipidemia • floating or broad β disease • mutation in apolipoprotein E • increased chylomicron remnants and IDL • increased serum triglycerides and cholesterol Type IV Hyperlipidemia • familial hypertriglyceridemia • unknown mutation • increased serum VLDL • increased serum triglycerides and cholesterol Type V Hyperlipidemia • mutation in apolipoprotein CII • increased serum chylomicrons and VLDL • increased serum triglycerides and cholesterol |
ANEURYSMS |
Atherosclerotic Aneurysms • cause → atherosclerosis • location → abdominal aorta (between renal arteries and bifurcation of the aorta) • pulsatile mass • may rupture → sudden, severe abdominal pain in male older than 55 • treat with surgery when diameter is > 5 cm Luetic Aneurysms • cause → syphilis (treponema) infection • obliterative endarteritis (plasma cells around small blood vessels) • location → ascending (thoracic) aorta • may produce aortic regurgitation or rupture Dissecting Aneurysms 1. Due to cystic medial necrosis of aorta • hypertension • Marfan’s syndrome → due to defect in fibrillin gene 2. “Double-barrel” aorta on x-ray Berry Aneurysms • location → bifurcation of arteries in circle of Willis • most commonly bifurcation of anterior communicating artery • subarachnoid hemorrhage • associated with polycystic renal disease |
CARDIAC HYPERTROPHY |
Concentric Hypertrophy • response to pressure overload (e.g., hypertension or aortic stenosis) • sarcomeres proliferate in parallel • increased ventricular thickness • no change in size of ventricular cavity Eccentric Hypertrophy • response to volume overload • sarcomeres proliferate in series • no increase in ventricle thickness • increase in size of ventricular cavity |
CONGENITAL HEART DEFECTS |
Left-to-Right Shunts 1. Ventricular septal defect (VSD) → most common congenital cardiac anomaly 2. Atrial septal defect (ASD) 3. Patent ductus arteriosus (PDA) • “machine-like” heart murmur • indomethacin closes PDA Right-to-Left Shunts 1. Tetralogy of Fallot (TOF) → most common cause of congenital cyanotic heart disease • pulmonary stenosis • ventricular septal defect • dextropositioned (overriding) aorta • right ventricular hypertrophy No Shunts 1. Coarctation of the aorta • infantile type (preductal) • adult type (postductal) → rib notching, increased BP in upper extremities, decreased BP in lower extremities 2. Transposition of the great vessels • need shunt to be present in order to survive (e.g., PDA) • PGE keeps ductus open |
ATROPHY OF THE STOMACH |
Type A ÆAutoimmune Gastritis • autoantibodies to parietal cells and intrinsic factor → pernicious anemia • decreased vitamin B12 → megaloblastic anemia • increased serum gastrin levels • histologic changes found in fundus of stomach Type B Æ Environmental • no autoantibodies present • associated with Helicobacter pylori (urease breath test is positive) • decreased serum gastrin levels • histologic changes found in antrum of stomach |
Ulcerative Colitis |
• crypt abscesses (microabscesses) and crypt distortion • disease begins in rectum and extends proximally (no skip lesions) • does not involve small intestines • superficial mucosal involvement (not transmural) • increased risk of colon cancer and toxic megacolon |
Crohn’s Disease |
• granulomas • segmental involvement (skip lesions) • may involve small intestines (regional enteritis or ileitis) • transmural involvement → fissures, fistulas, and obstruction |
GALLSTONES |
Cholesterol Stones • yellow stones • risk factors → Fs = fat, female, fertile, forty, fifty • increased incidence in Native Americans Bilirubin (Pigment) Stones • black stones • risk factors → chronic hemolysis and infections of biliary tract • increased incidence in Asians |
CONGENITAL ADRENAL HYPERPLASIA (CAH) |
21-Hydroxylase Deficiency • decreased cortisol → increased ACTH • decreased aldosterone • sodium loss in the urine → salt-wasting form of CAH • hyperkalemic acidosis • virilism in females 11-Hydroxylase Deficiency • decreased cortisol → increased ACTH • decreased aldosterone • increased DOC and 11-deoxycortisol → increased mineralocorticoid effects • sodium retention → hypertensive form of CAH • hypokalemic alkalosis • virilism in females 17-Hydroxylase Deficiency • decreased cortisol → increased ACTH • no decreased aldosterone • decreased sex hormones • females → primary amenorrhea • males → pseudohermaphrodites |
MULTIPLE ENDOCRINE NEOPLASIA |
Type 1 (Wermer’s Syndrome) • parathyroid • pituitary • pancreas Type 2 (Sipple’s Syndrome) • parathyroid • medullary carcinoma of thyroid • pheochromocytoma Type 3 (MEN 2B) • medullary carcinoma of thyroid • pheochromocytoma • mucosal neuromas |
Nephrotic Syndrome |
• marked proteinuria → hypoalbuminemia and edema • increased cholesterol → oval fat bodies in the urine Examples (nonproliferative glomerular disease): 1. Minimal change disease (lipoid nephrosis) • normal light microscopy • EM reveals fusion of foot processes of podocytes 2. Focal segmental glomerulosclerosis (FSGS) 3. Membranous glomerulonephropathy (MGN) • thickening of basement membrane (“spikes and domes”) • uniform subepithelial deposits 4. Diabetes mellitus |
Nephritic Syndrome |
• hematuria (red blood cells and red blood cell casts in urine) • variable proteinuria and oliguria • retention of salt and water (hypertension and edema) Examples (proliferative glomerular disease): 1. Focal segmental glomerulonephritis (FSGN) • mesangial deposits of IgA • Berger’s disease 2. Acute (diffuse) proliferative glomerulonephritis (DPGN) • post-streptococcal glomerulonephritis • large, irregular subepithelial deposits 3. Membranoproliferative glomerulonephritis (MPGN) • subendothelial deposits → type I MPGN • intramembranous deposits →type II MPGN (dense deposit disease) • splitting of basement membrane by mesangium → “tram-track” appearance 4. Rapidly progressive glomerulonephritis (RPGN) |
GLOMERULAR DEPOSITS |
Subepithelial • diffuse proliferative glomerulonephritis (DPGN) → irregular and large • membranous glomerulonephropathy (MGN) → uniform and small Intramembranous (Basement Membrane) • membranoproliferative glomerulonephritis (MPGN), type II Subendothelial • membranoproliferative glomerulonephritis, type I • SLE Mesangial • focal segmental glomerulonephritis (FSGN) • Henoch-Schönlein purpura |
RAPIDLY PROGRESSIVE GLOMERULONEPHRITIS (RPGN) |
Linear Immunofluorescence • antimembrane antibody • Goodpasture’s disease Granular Immunofluorescence • immune complexes • other glomerular or systemic disease Minimal or Negative Immunofluorescence • pauci-immune disease • Wegener’s granulomatosis • microscopic polyarteritis nodosa |
CEREBRAL HEMORRHAGE |
Epidural Hematoma • severe trauma • arterial bleeding (middle meningeal artery) • symptoms occur rapidly Subdural Hematoma • minimal trauma in elderly • venous bleeding (bridging veins) • symptoms occur slowly Subarachnoid Hemorrhage • rupture of berry aneurysm • “worst headache ever” • bloody or xanthochromic spinal tap |
INFECTIONS OF THE MENINGES |
Bacterial Infections • increased neutrophils and protein in CSF • decreased glucose in CSF • life-threatening Neonates – Escherichia coli 6 months to 6 years – Streptococcus pneumoniae 6 years to 16 years – Neisseria meningitidis (meningococcus) Older than 16 years – Streptococcus pneumoniae Epidemics – Neisseria meningitidis Viral Infections • increased lymphocytes in CSF • normal glucose in CSF • mild and self-limited |
Alzheimer’s Disease |
• diffuse atrophy of cerebral cortex • dementia (most common cause in elderly) • senile plaques (with β-amyloid core) • neurofibrillary tangles (with abnormal τ protein) |
Pick’s Disease |
• unilateral frontal or temporal lobe atrophy |
Huntington’s Disease |
• trinucleotide repeat disorder |
Parkinson’s Disease |
• substantia nigra (depigmentation) • decreased dopamine in corpus striatum • cogwheel rigidity and akinesia • tremor • treatment → dopamine agonists |
Rheumatoid Arthritis |
• rheumatoid factor (IgM antibody against antibody) • pannus formation in synovium (hyperplastic synovium with lymphocytes and plasma cells) • ulnar deviation of fingers • subcutaneous rheumatoid nodules (at pressure points) • pain worse in morning (“morning stiffness”); pain decreases with activity |
Osteoarthritis |
• degenerative joint disease (“wear and tear”) • loss of articular cartilage → smooth subchondral bone (eburnation) • osteophyte formation (DIP →Heberden’s nodes, PIP →Bouchard’s nodes) • pain worse in evening; pain increases with activity |
Gout |
• hyperuricemia → precipitation of monosodium urate crystals (needleshaped, negatively birefringent crystals) • first MTP joint (big toe) • tophus formation • increased production of uric acid → Lesch-Nyhan syndrome • increased turnover of nucleic acid → leukemias and lymphomas • decreased excretion of uric acid →chronic renal disease, ethanol intake, diabetes |
ENZYMES |
Aminotransferases (AST,ALT) • myocardial infarction (AST) • alcoholic hepatitis (AST > ALT) • viral hepatitis (ALT > AST) Creatine Kinase (CK or CPK) • myocardial infarction (CPK-MB) • muscle diseases (DMD) Lactate Dehydrogenase (LDH) • myocardial infarction (LDH1, LDH2) Amylase or Lipase • acute pancreatitis |
HISTOLOGIC “BODIES” |
1. Psammoma body: • papillary carcinoma of the thyroid • papillary tumors of the ovary • meningioma 2. Immunoglobulin • Russell body → cytoplasmic or extracellular • Dutcher body → nucleus (Waldenstrom’s) 3. Councilman body → viral hepatitis 4. Mallory body → alcoholic hyaline 5. Cowdry A body → herpes 6. Aschoff body → rheumatoid fever 7. Ferruginous body → asbestos 8. Negri body → rabies 9. Lewy body → Parkinson’s 10. Heinz body (denatured hemoglobin) → G6PD deficiency 11. Barr body → number of X chromosomes minus one |
HEALING OF THE MYOCARDIUM AFTER A MYOCARDIAL INFARCTION |
0–12 h None Usually none (?wavy fibers) 12–24 h Pallor Coagulative necrosis 1–3 days Hyperemic (red) border Above+neutrophils 4–7 days Pale yellow Above + macrophages 7–14 days Red-purple border Above + granulation tissue >2 weeks Gray-white scar Fibrosis (scar) |
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