📖 General Pathology
Mycobacterium leprae
General PathologyMycobacterium leprae
- tuberculoid type has intact cellular immunity
- forms granulomas and kill the organisms (very few present).
- evokes a positive lepromin skin test
- localized skin lesions that lack symmetry
- nerve involvement (organisms invade Schwann cells) that dominates the clinical picture and leads to skin anesthesia, muscle atrophy and autoamputation.
- lepromatous leprosy patients lack cellular immunity
- no granulomas
- organisms readily identified
- negative lepromin skin test
- Bacteremia disseminates to cooler areas like the digits.
- symmetrical, skin lesions that produce the classic leonine facies; biopsy reveals grentz zone in superficial dermis and then organisms in macrophages.
- neural involvement is a late feature of the disease.
- lepromin skin test is to determine host immunity; not a diagnostic test.
- treatment: dapsone + rifampin
EMBOLISM
General PathologyEMBOLISM
Definition: transportation of an abnormal mass of an abnormal mass of undissolved material from one part of circulation to another. The mass transported is called embolus.
Types
I .Thrombi and clots.
2. Gas or air.
3. Fat
4.Amniotic fluid.
5.Tumour
Thromboembolism
This is the commonest type of embolus and may be formed of the primary thrombus or more often of propagated clot region which is loosely attached.
Emboli from venous thrombi can result In impaction in the pulmonary arteries and result in sudden death.
Embolism from cardiac or arterial thrombi results in systemic embolism causing infraction and gangrene.
Gaseous
This occurs when gas is introduced into the circulation:
• Accidental opening of large veins during surgery.
• Mismanaged transfusion. .
As air is readily absorbed into blood only sudden introduction or large quantities of air produces effects
Caisson’s Disease bubbling of nitrogen from the blood during sudden decompression as seen during deep sea diving.
Fat Embolism
Causes
• Fractures especially of long bones and multiple
• Crush injuries.
Sites of impaction:
o Lungs.
o Systemic: causing -
→ petechial skin haemorrhages.
→ Embolism to brain leading to coma and death.
→ Conjunctival and retinal haemorrhages
Tumor Embolism.
Invasion of vascular channe1.s is a feature of malignant neoplasms and this leads to:
• Metastatic deposits,
• DlC
Cholangitis
General PathologyCholangitis
Cholangitis is inflammation of the bile ducts.
1. It is usually associated with biliary duct obstruction by gallstones or carcinoma, which leads to infection with enteric organisms. This results in purulent exudation within the bile ducts and bile stasis.
2. Clinically, cholangitis presents with jaundice, fever, chills. leukocytosis, and right upper quadrant pain
Acute pericarditis
General PathologyAcute 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.