NEET MDS Lessons
General Pathology
Chronic hepatitis
Chronic hepatitis occurs in 5%-10% of HBV infections and in well over 50% of HCV; it does not occur in HAV. Most chronic disease is due to chronic persistent hepatitis. The chronic form is more likely to occur in the very old or very young, in males, in immunocompromised hosts, in Down's syndrome, and in dialysis patients.
a. Chronic persistent hepatitis is a benign, self-limited disease with a prolonged recovery. Patients are asymptomatic except for elevated transaminases.
b. Chronic active hepatitis features chronic inflammation with hepatocyte destruction, resulting in cirrhosis and liver failure.
(1) Etiology. HBV, HCV, HDV, drug toxicity, Wilson's disease, alcohol, a,-antitrypsin deficiency, and autoimmune hepatitis are common etiologies.
(2) Clinical features may include fatigue, fever, malaise, anorexia, and elevated liver function tests.
(3) Diagnosis is made by liver biopsy.
8. Carrier state for HBV and HCV may be either asymptomatic or with liver disease; in the latter case, the patient has elevate transaminases.
a. Incidence is most common in immunodeficient, drug addicted, Down's syndrome, and dialysis patients.
b. Pathology of asymptomatic carriers shows "ground-glass"" hepatocytes with finely granular eosinophilic cytoplasm.
Rheumatic fever
Before antibiotic therapy, this was the most common cause of valvular disease.
1. Usually preceded by a group A streptococci respiratory infection; for example, strep throat.
2. All three layers of the heart may be affected. The pathologic findings include Aschoff bodies, which are areas of focal necrosis surrounded by a dense inflammatory infiltration.
3. Most commonly affects the mitral valve, resulting in mitral valve stenosis, regurgitation, or both.
Clinical & biologic death
Clinical death
Clinical death is the reversible transmission between life and biologic death. Clinical death is defined as the period of respiratory, circulatory and brain arrest during which initiation of resuscitation can lead to recovery.
Signs indicating clinical death are
• The patient is without pulse or blood pressure and is completely unresponsive to the most painful stimulus.
• The pupils are widely dilated
• Some reflex reactions to external stimulation are preserved. For example, during intubations, respiration may be restored in response to stimulation of the receptors of the superior laryngeal nerve, the nucleus of which is located in the medulla oblongata near the respiratory center.
• Recovery can occur with resuscitation.
Biological Death
Biological death (sure sign of death), which sets in after clinical death, is an irreversible state
of cellular destruction. It manifests with irreversible cessation of circulatory and respiratory
functions, or irreversible cessation of all functions of the entire brain, including brain stem.
Cholangitis
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
Immunohistochemistry
This is a method is used to detect a specific antigen in the tissue in order to identify the type of disease.
CONGESTION
Congestion or hyperaemia means an increase in the content of blood in an organ. It may be :
A. Active - due to increased arterial flow to the organ with dilatation of micro vessels as in
- Inflammation.
- Increased metabolic activity.
- Neurogenic blushing.
B. Passive - due to decreased venous drainage resulting in pooling of blood. There is always an associated element of oedema.
PERTUSSIS (Whooping Cough)
An acute, highly communicable bacterial disease caused by Bordetella pertussis and characterized by a paroxysmal or spasmodic cough that usually ends in a prolonged, high-pitched, crowing inspiration (the whoop).
Transmission is by aspiration of B. pertussis
Symptoms and Signs
The incubation period averages 7 to 14 days (maximum, 3 wk). B. pertussis invades the mucosa of the nasopharynx, trachea, bronchi, and bronchioles, increasing the secretion of mucus, which is initially thin and later viscid and tenacious. The uncomplicated disease lasts about 6 to 10 wk and consists of three stages: catarrhal, paroxysmal, and convalescent.