Klinefelter’s syndrome (XXY). Phenotype in-cludes a female fat distribution with male ex-ternal genitalia.

Turner’s syndrome (XO). Phenotype includesshort stature, webbing of the neck, and poorlydeveloped secondary sex characteristics.

Granulomatous inflammation with Langhan’s giantcell, epithelioid cells, and caseous necrosis, microscopic.

Streptococcus pneumoniae. Sputum sample from a pa-tient with pneumonia shows gram-positive diplococci.

Taenia solium, the pig tapeworm, infesting porcine my-ocardium. When humans injest this meat, the larvae at-tach to the wall of the small intestine and mature toadult worms.

Intracytoplasmic inclusions

Trophozoites of Trichomonas vaginalis by Giemsa stain.

Staphylococcus aureus. Sputum sample from anotherpatient with pneumonia shows gram-positive cocci inclusters.

Candidal vaginitis. Branched and budding Candida albi-cans visable on KOH preparation of whitish vaginal dis-charge.

Giardia lamblia, small intestine, microscopic. Tropho-zoite has a classic pear shape with double nuclei givingan owl’s eye appearance.

Cryptococcus neoformans, polysaccaride capsule vis-ible by India ink preparation, in CSF from an AIDSpatient with meningoencephalitis.

Cytomegalovirus (CMV) giant cell with multiple hya-line inclusions in a renal tubule. Of special concern inHIV patients (CMV retinitis) and organ transplant pa-tients (as here, in a transplanted kidney); however,CMV can infect almost anything. Treatment is gangi-clovir or foscarnet.

Acute lymphocytic leukemia, peripheral blood smear,from a 10-year old child.

Chronic lymphocytic leukemia, peripheral blood smear,microscopic. In CLL, the lymphocytes are excessivelyfragile. These lymphocytes are easily disrupted duringslide preparation, forming “smudge cells” (arrow).

Acute myelogenous leukemia with Auer rod (arrow),peripheral blood smear.

Hodgkin’s disease (Reed-Sternberg cells). Binu-cleate RS cells displaying prominent inclusion-like nucleoli surrounded by lymphocytes andother reacting inflammatory cells. The RS cell is anecessary but insufficient pathologic finding forthe diagnosis of Hodgkin’s disease.

Smears from a patient with multiple myeloma, displaying an abundance of plasma cells. RBCs will often be seen inrouleaux formation, stacked like poker chips. Multiple myeloma is associated with hypercalcemia, lytic bone lesions,and renal insufficiency due to Bence Jones (light-chain) proteinuria.

Sickle cell anemia: note the sickled cells as wellas anisocytosis, poikilocytosis, and nucleatedRBCs.

Iron deficiency anemia: microcytosis and hypochromia. Duodenal ulcer: the epithelium is ulcerated, and thelamina propria is infiltrated with inflammatory cells.Necrotic debris is present in the ulcer crater.

CT abdomen with contrast—normal anatomy.

1 Liver 7 Splenic vein2 Inferior vena cava 8 Aorta3 Portal vein 9 Spleen4 Hepatic artery 10 Stomach5 Gastroduodenal artery 11 Pancreas6 Celiac trunk

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Left adrenal mass.

1 Large left adrenal mass2 Kidney3 Vertebral body4 Aorta5 IVC6 Pancreas7 Spleen8 Liver9 Stomach with air and contrast

10 Colon–splenic flexure

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Photomicrograph of the small intestine.

Celiac sprue (gluten-sensitive enteropathy): histologyshows blunting of villi and crypt hyperplasia.

Colonic polyps. Tubular adenomas (A) are smaller and rounded in morphology, and have less malignant po-tential than villous adenomas (B), which are composed of long, finger-like projections.

A B

Inflammatory Bowel Disease (IBD). In Crohn’s disease (A), the juxtaposition of ulcerated and normalmucosa gives a “cobblestone” appearance. In acute ulcerative colitis (B), the intestinal mucosa is in-flamed and edematous and has a pseudopolypoid appearance. Chronically, ulcerative colitis has a more at-rophic appearance.

A B

Hemochromatosis with cirrhosis, Prussian blue ironstain showing hemosiderin in the liver parenchyma.Such deposition occurs throughout the body, causingorgan damage and the characteristic darkening of theskin.

Metastatic carcinoma to liver: most common primarysites are colon, breast or lung.

Fatty metamorphosis (macrovesicular steatosis) of liver,microscopic. Early reversible change associated with al-cohol consumption; there are abundant fat-filled vac-uoles but no inflammation or fibrosis of more serious al-coholic liver damage (yet).

Micronodular cirrhosis of liver, gross, from an alco-holic patient. Liver is approximately normal in size,with a fine granular appearance. Later stages of diseaseresult in an irregularly shrunken liver with larger nod-ules.

Pyknotic nuclei

Coagulative necrosisof liver cells

Disorganized

Pyknotic or absentnuclei

Homogeneouscytoplasm

Normal livercells

Arranged in cords

Normal nuclei

Granular cytoplasm

Coagulative necrosis of hepatocytes.

Caput medusae (periumbilical venous distension) withportal hypertension, in a patient with cirrhosis.

Splenic infarction. The splenic artery lacks collateralsupply, making the spleen particularly susceptible to is-chemic damage. Coagulative necrosis has occurred in awedge shape, along the pattern of vascular supply.

Cirrhosis, microscopic: regenerative lesions are sur-rounded by fibrotic bands of collagen, forming thecharacteristic nodularity.

Compare the diffuse, patchy, bilateral infiltrates of “atypical” interstitial pneumonia (A), with the localized dense le-sion of lobar pneumonia (B).

Bronchopneumonia with neutrophils in alveolar spaces,microscopic.

Bronchopneumonia, gross: note the large areaof consolidation at the base plus multiplesmall areas of consolidation (pale) involvingbronchioles and surrounding alveolar sacsthroughout the lung.

A B

Microscopically, tuberculosis (A) is characterized by caseating granulomas containing Langhan’s giant cells, which have a“horseshoe” pattern of nuclei (see arrow). Organisms (B) are identified by their red color on acid-fast staining (“red snap-pers”).

A B

Coccioidomycosis: endospores within a spherule in in-fected lung parenchyma. Initial infection usually re-solves spontaneously, but when immunity is compro-mised, dissemination to almost any organ can occur.Endemic in Southwest U.S.

Asbestosis: ferruginous bodies (asbestos bodies withPrussian blue iron stain) in lung, microscopic. Inhaledasbestos fibers are injested by macrophages.

Squamous cell carcinoma of lung, gross, from a patientwith a long smoking history. This tumor arises from thebronchial epithelium and is centrally located.

Squamous cell carcinoma, histologic: a nest of poly-gonal cells with pink cytoplasm and hyperchromaticnuclei.

Tension pneumothorax.

Note these features:

1 Hyperlucent lung field2 Hyperexpansion lowers diaphragm3 Collapsed lung4 Deviation of trachea5 Mediastinal shift6 Compression of opposite lung

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Acute respiratory distress syndrome (ARDS). Persis-tent inflammation leads to poor pulmonary complianceand edema; note both alveolar fluid and hyaline mem-branes.

Inflammation and smooth muscle hypertrophy in bron-chial asthma.

Saddle pulmonary thromboembolus, gross. Most oftenarises from deep venous thrombosis.

Brain with neuritic plaques indicative of Alzheimer’sdisease, Bielschowsky silver stain, microscopic.

Alzheimer’s disease. Key histologic features include “se-nile plaques” (1), focal masses of interwoven neuronalprocesses around an amyloid core. The amyloid corestains with Congo red dye and shows apple-green bire-fringence under polarized light (2). Neurofibrillary tan-gles (3), the remnants of neuronal degeneration, arealso associated with Alzheimer’s disease, the most com-mon cause of dementia in older persons.

1.

3.

2.

Epidural hematoma from skull fracture. Note lens-shaped (biconcave) dense blood next to fracture. 1 Skullfracture; 2 Hematoma in epidural space; 3 Temporalismuscle; 4 Sylvian fissure; 5 Frontal sinus.

Subdural hemorrhage. Note hyperdense extra-axial bloodon the left side. Concomitant subarachnoid hemorrhage. 1 Subdural blood, layering; 2 Skull; 3 Falx; 4 Subarach-noid blood; 5 Shunt catheter; 6 Frontal sinus.

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Subarachnoid hemorrhage. CT scan with contrast reveals blood in the subarachnoid space at the base of the brain.(arrows). (B) A normal noncontrast CT scan shows no density in this region

A B

Left MCA stroke. Large left MCA territory stroke withedema and mass effect, but no visible hemorrhage. Pa-tient experienced deficits in speech and in the right sideof the face and upper extremities. 1 Ischemic brainparenchyma; 2 Subtle midline shift to the right; 3 Rightfrontal horn of lateral ventricle; 4 Left lateral ventriclesobliterated by edema.

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Brain with hypertensive hemorrhage in the region ofthe basal ganglia, gross.

Gram negative diplococci of Neisseria meningitidiswithin a neutrophil, from CSF.

Brain with periventricular white matter plaques of de-myelination due to multiple sclerosis, gross. Demyeli-nation occurs in a bilateral asymmetric distribution.Classic clinical findings are nystagmus, scanningspeech, and intention tremor.

Electron micrograph of a peripheral nerve. (M)myelinated and (U) unmyelinated nerve fibers.(RF) reticular fibers (part of the endoneurium), (S)Schwann cell nucleus, (P, arrows) perineurial cells.

Rheumatoid arthritis: notice the swan-neck deform-ities of the digits and severe, symmetric involvementof the proximal interphalangeal (PIP) joints.

Glioblastoma multiforme extending across the midline of cerebral cortex, gross (A). Histologically (B), tumor cellshave a “pseudopalisading” appearance around the necrotic tumor.

A B

Scleroderma. The progressive “tightening” of the skinhas contracted the fingers and eliminated creases overthe knuckles. Fibrosis is widespread and may also in-volve the esophagus (dysphagia), lung (restrictive dis-ease), and small vessels of the kidney (hypertension).

Electron micrograph of a pancreatic acinar cell.A condensing vacuole (C) is receiving secre-tory product (arrow) from the Golgi complex(G). Mitochondrion (M); rough endoplasmicreticulum (RER); mature condensed secretoryzymogen granules (S).

Pancreatic islet cells in DM Type I. In patients with di-abetes mellitus type I, autoantibodies against B cellscause a chronic inflammation until, over time, islet cellsare entirely replaced by amyloid.

In Graves’ disease, stimulation of follicular cells by TSH causes the normal uniform architecture to be replaced by hy-perplastic papillary, involuted borders, and decreased colloid (A, B). Typical medical therapy is propylthiouracil,which inhibits production of thyroid hormone as well as peripheral conversion of T4 to T3.

BA

Cushing’s disease. The clinical picture includes (A) moon facies and buffalo hump and (B) truncal obesity and ab-dominal striae.

Exophthalmos in a patient with Graves’ disease, withproptosis and periorbital edema.

A B

In the seminiferous tubules, Sertoli cells play a sup-portive and protective role for spermatogenesis. Notecells in various stages of differentiation, with spermato-gonia near the basal lamina and more mature forms nearthe lumen.

Adrenal cortical adenoma, gross. Cause of hypercorti-solism (Cushing’s syndrome) or hyperaldosteronism(Conn’s syndrome).

Serosal surface of uterus with “powder burn” lesions ofendometriosis, gross. Ovarian chocolate cysts, due tobleeding of ectopic endometrial tissue, are another char-acteristic finding. Patients experience pain with men-struation.

Hydatidiform mole: the characteristic gross appearanceis a “bunch of grapes.” Hydatidiform moles are the mostcommon precursors of choriocarcinoma. Completemoles usually display a 46, XX diploid pattern with allthe chromosomes derived from the sperm. In partialmoles, the karyotype is triploid or tetraploid, and fetalparts may be present.

Teeth

Respiratoryepitheliumand glands

Glial tissueStratified squamousepitheliumHair

A benign teratoma of the ovary, containing teeth and hair, an incidental finding during abdominal surgery. In females,teratomas are generally benign, while in males, they account for about 30% of testicular tumors.

Multiple leiomyomas (fibroids) of the uterus. Commonbenign uterine tumor. Fibroids beneath the en-dometrium may present with vaginal bleeding; they alsodevelop subserosally or within the myometrium.

Evolution of a myocardial infarction: (1) Contraction band necrosis is the first visible change, occurring in 1–2 hours.(2) In the first 3 days, neutrophilic infiltration and coagulation necrosis occur. (3) By 3–7 days, neutrophils have beenreplaced by macrophages, and clearing of myocyte debris has begun. (4) Within weeks, granulation and scarring occur.

1. 2.

3. 4.

Atherosclerosis in a coronary vessel. Calcified plaqueshave narrowed the lumen of the artery, increasing therisk for occlusion, ie, myocardial infarction.

Lumen of vessel(narrowed to about 5% of original lumen)

Fattyatheroscleroticplaque(lipid zone)

Fibrous cap

Calcification

Heart with marked left ventricular hypertrophy fromhypertension, gross.

Aortic dissection, with blood compressing the aortic lu-men. A tear in the intima allowed blood to surgethrough the muscular layer to the adventitia. Risk fac-tors are hypertension, Marfan’s syndrome, pregnancy.

The Aschoff body, an area of fibrinoid necrosissurrounded by mononuclear and multinucleatedgiant cells, is pathognomonic for rheumaticheart disease. The mitral valve is most com-monly affected.

Acute bacterial endocarditis: virulent organisms (e.g.,Staphylococcus aureus) infect previously normalvalves, causing marked damage (here, in the aorticvalve) and potentially giving rise to septic emboli.

Normal glomerulus, microscopic, with (A) maculadensa, (B) afferent and (C) efferent arterioles.

Diabetic nodular glomerulosclerosis. The nodular Kim-melstiel-Wilson lesions at the periphery of the glomeru-lus are pathognomonic for diabetic GS.

Systemic lupus erythematosus: kidney pathology. Inthe membranous glomerulonephritic pattern, “wire-loop” thickening occurs due to subendothelial immunecomplex deposition.

Minimal change disease (lipoid nephrosis) shows nor-mal glomeruli on light microscopy but effacement offoot processes on EM (arrowhead). The full arrow pointsto a normal foot process.

In Goodpasture’s syndrome (A), antiglomerular basement membrane antibody creates a linear pattern by immunofluo-rescence (microscopic); compare with the granular immune deposits seen by immunofluorescence in poststreptococcalglomerulonephritis (B).

A B

Renal cell carcinoma, microscopic. Glycogen and lipid-filled clear cells are derived from tubular epithelium.

Renal cell carcinoma, gross. Notably, tumor may extendinto the renal vein and IVC and spread hematogenously.

Acute pyelonephritis (A) is characterized by neutrophilic infiltration and abcess formation within the renal intersti-tum. Abcesses may rupture, introducing collections of white cells to the tubular lumen (arrow). In contrast, chronicpyelonephritis (B) has a lymphocytic invasion with fibrosis.

A B

Transitional cell carcinoma of the urinary bladder, mi-croscopic. Malignant urothelial cells have invaded themuscular layer of the bladder wall.

Autosomal-dominant polycystic kidney disease, gross.Disease occurs bilaterally and presents with flank painand hematuria.

Fetal bone growth plate, endochondral bone formationin long bone. At the transitional zone, osteoblasts con-gregate to replace cartilage with bone.

Anterior shoulder dislocation. Note humeral head in-ferior and medial to glenoid fossa and fracture fragmentsfrom greater tuberosity.

1 Acromion2 Coracoid3 Glenoid fossa4 Fracture fragments5 Humeral head6 Clavicle

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