USMLE Pathology Slides

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Heart: cardiac tamponade secondary to rupture of the left ventricle in a patient with an AMI  At the apex of the heart, there is a rupture site in the area of a transmural AMI. Blood fills the pericardial sac and encircles the heart

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Heart: microscopic section of a 3 day old acute myocardial infarction Unlike the previous slide, which showed the early stages of coagulation necrosis, this slide depicts a heavy neutrophilic infiltrate with destruction of the cardiac fibers. The neutrophils came into the area of the infarct from the periphery, so this should not be confused with liquefactive necrosis. Macrophages will eventually replace the neutrophils and then collagen tissue will be deposited in the area of infarction.

[usmlepathslides]

Heart: mitral valve prolapse  Note the baggy-appearing mitral valve leaflets. When blood collects beneath these voluminous valves, it projects them into the left atrium like a parachute. When the chordae abruptly stop the valves from moving any further, a systolic click is heard followed by a murmur of mitral insufficiency.

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Heart: right and left ventricular hypertrophy  The left ventricle is on your left and the right ventricle on your right. Note that both ventricles are thickened. One possible explanation for RV hypertrophy is pulmonary artery hypertension, which imposes an increased afterload against the RV.

[usmlepathslides]

Heart: coagulation necrosis of cardiac muscle in an AMI Note the eosinophilic staining cells with no cross striations or nuclei.

[usmlepathslides]

Coronary artery: coronary artery atherosclerosis and thrombus occluding the lumen  Note the red thrombus overlying an atheromatous plaque (arrow). The slit like spaces are where cholesterol used to be present.

[usmlepathslides]

Heart: heart with coronary artery bypasses using saphenous vein grafts Note the 2 veins, one bypassing the LAD coronary artery (arrow) and the other the RCA.

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Right coronary artery angiogram RCA stenosis secondary to atherosclerosis. Note the area of constriction (arrow) in the mid-portion of the coronary artery.

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Aorta: postductal coarctation of the aorta 

Note the area of constriction just distal to the ligamentum arteriosum (arrow) extending off the transected pulmonary artery. The proximal aorta is dilated and the posterior wall of the aorta hit by the jet-stream of blood going through the narrow opening is also aneurysmally dilated. You can trace a figure 3 lying on its side

[usmlepathslides]

Abdominal CT, spleen lac

Common causes of splenic lacerations include MVC or other high speed deceleration injuries. These produce lower rib fractures which can lacerate the spleen or liver. The patient may present with LUQ pain and referred pain to the shoulder secondary to phrenic nerve irritation (Kehr's sign)

[usmlepathslides]

Bells palsy

Caused by lesion on the seventh cranial nerve, bells palsy is characterized by a unilateral facial paralysis. It is further divided into peripheral lesions (patient unable to wrinkle forehead) and central lesions (patient able to wrinkle forehead). Peripheral type can be managed with a steroid burst, acyclovir and an eye patch. Central type will typically require an MRI to look for the lesion. 

Bilateral bells palsy can be seen in Lyme disease. 

[usmlepathslides]

Posterior hip dislocation

Posterior hip dislocations account for approximately 90% of dislocations at this joint. The classic mechanism is a flexed knee striking the dashboard during a motor vehicle collision. Note that the right knee is flexed, the leg is ADDucted at the hip and INTERNALLY rotated. The entire right leg is also shortened. The hip must be reduced quickly as the dislocation can compromise femoral head blood supply leading to avascular necrosis. A useful mnemonic to remember rotation with hip dislocations in PIN AXE (posterior - internal, anterior external). Anterior dislocations rotate externally. 

[usmlepathslides]

cecal voluvlus, AXR

Classic test question is a young marathon runner with prior abdominal surgeries who presents with acute abdominal pain. Abdominal imaging shows several distended loops of small bowel and coffee bean shaped hypodensity. Contrast this with the sigmoid volvulus, classically occurring in elderly individuals with chronic constipation and abdominal distension. The treatment for both is NGT decompression and surgery. 

[usmlepathslides]

CXR, swallowed foreign body (FB)

Swallowed foreign bodies (such as coins) lodged in the esophagus are classically seen in the coronal plane on CXR while tracheal obstructions present in the sagittal plane. This holds true for the purpose of exams but in clinical practice this is not always the case. 

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axillary nerve palsy

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ACHONDROPLASIA

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Adrenal calcification, ACT

Extrapulmonary tuberculosis is the most common cause of adrenal insufficiency in developing countries while autoimmune adrenalitis is the most common cause in developed countries. Abdominal CT may show adrenal calcification. Other infectious causes include CMV and fungal infections. TB treatment will not reverse the AI and patients often need chronic glucocorticoid replacement.