Immunohistochemistry

 This is a method is used to detect a specific antigen in the tissue in order to identify the type of disease.

Metastatic Tumors 

These are the most common malignant tumor of bone. Certain tumors exhibit a distinct skeletal prediliction. In adults more than 75% of skeletal metastases originate from cancers of the prostate, breast, kidney, and lung. In children, neuroblastoma, Wilms' tumor, osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma are the common sources of bony metastases. Most metastases involve the axial skeleton (vertebral column, pelvis, ribs, skull, sternum), proximal femur, and humerus. The radiologic appearance of metastases can be purely osteolytic, purely osteoblastic, or mixed osteolytic-osteoblastic (majority of cases). In lytic lesions (e.g., kidney& lung), the metastatic cells secrete substances such as prostaglandins, interleukins, etc. that stimulate osteoclastic bone resorption; the tumor cells themselves do not directly resorb bone. Similarly, metastases that elicit a blastic response (e.g., prostate adenocarcinoma) do so by stimulating osteoblastic bone formation.

Acute pericarditis

1. Characterized by inflammation of the pericardium.
2. Causes include:
a. Viral infection.
b. Bacterial infection, including Staphylococcus, Pneumococcus.
c. Tuberculosis.
d. MI.
e. Systemic lupus erythematosus.
f. Rheumatic fever.

3. Signs and symptoms include:
a. Pericardial friction rub on cardiac auscultation.
b. Angina.
c. Fever.

4. Consequences include constrictive pericarditis,which results from fusion and scarring of the pericardium. This may lead to the restriction of ventricular expansion, preventing the heart chambers from filling normally.

Alzheimer’s disease
a. The most common cause of dementia in older people.
b. Characterized by degeneration of neurons in the cerebral cortex.
c. Histologic findings include amyloid plaques and neurofibrillary tangles.
d. Clinically, the disease takes years to develop and results in the loss of cognition, memory, and the ability to ommunicate. Motor problems, contractures, and paralysis are some of the symptoms at the terminal stage.

Pernicious anaemia 

The special features are:

• Due to intrinsic factor deficiency
• Gastric atrophy with histamine fast achlorhydria
• Genetic basis (racial distribution and blood group A).
• Seen with auto immune disorders.
• Antibodies to parietal cells and to intrinsic factors are seen

Myocardial infarction (MI)—heart attack

A. Ischemia versus MI: Ischemia is a reversible mismatch between the supply and demand of oxygen. Infarction
is an irreversible mismatch that results in cell death caused by the lack of blood flow (oxygenation). For instance, chest pain caused by ischemia can be relieved by administering nitroglycerin (a vasodilator) to the patient. If the patient has an MI, the pain will not be relieved with nitroglycerin.

1. MIs most commonly occur when a coronary artery is occluded by a thrombus generated in an atherosclerotic artery.

2. Symptoms include:
a. Chest pain, shortness of breath.
b. Diaphoresis (sweating), clammy hands.
c. Nausea, vomiting.

3. Consequences:
a. Death (one third of patients).
b. Arrhythmias (most common immediate cause of death).
c. Congestive heart failure.
d. Myocardial rupture, which may result in death from cardiac tamponade.
e. Thrombus formation on infarcted tissue; may result in systemic embolism.