NEET MDS Lessons
General Pathology
Rocky Mountain Spotted Fever (Spotted Fever; Tick Fever; Tick Typhus)
An acute febrile disease caused by Rickettsia rickettsii and transmitted by ixodid ticks, producing high fever, cough, and rash.
Symptoms and Signs
The incubation period averages 7 days but varies from 3 to 12 days; the shorter the incubation period, the more severe the infection. Onset is abrupt, with severe headache, chills, prostration, and muscular pains. Fever reaches 39.5 or 40° C (103 or 104° F) within several days and remains high (for 15 to 20 days in severe cases),
Between the 1st and 6th day of fever, most patients develop a rash on the wrists, ankles, palms, soles, and forearms that rapidly extends to the neck, face, axilla, buttocks, and trunk. Often, a warm water or alcohol compress brings out the rash. Initially macular and pink, it becomes maculopapular and darker. In about 4 days, the lesions become petechial and may coalesce to form large hemorrhagic areas that later ulcerate
Neurologic symptoms include headache, restlessness, insomnia, delirium, and coma, all indicative of encephalitis. Hypotension develops in severe cases. Hepatomegaly may be present, but jaundice is infrequent. Localized pneumonitis may occur. Untreated patients may develop pneumonia, tissue necrosis, and circulatory failure, with such sequelae as brain and heart damage. Cardiac arrest with sudden death occasionally occurs in fulminant cases.
ANAEMIA
Definition. Reduction of the hemoglobin level below the normal for the age and sex of the patient
Classification
1. Blood loss anaemia:
- Acute.
- Chronic (results in iron deficiency).
2. Deficiency anaemia:
- Iron deficiency.
- Megaloblastic anaemia-BI2 and Folic acid deficiency.
- Protein deficiency.
- Scurvy-Vitamin C deficiency.
3. Marrow dysfunction:
- Aplastic anaemia.
- Marrow infiltration.
- Liver failure.
- Renal failure.
- Collagen diseases.
4 Increased destruction (Heamolysis)
- Due to corpuscular defects.
- Due to extra corpuscular defects
Nephrosclerosis
Disease of the renal arteries.
Clinical manifestations:
(1) Benign (arterial) nephrosclerosis → Caused by the formation of atherosclerotic plaques in the renal artery. Results in narrowing of the arterioles.
(2) Malignant nephrosclerosis → Caused by malignant hypertension. Common signs of malignant hypertension include severe hypertension, retinal hemorrhages, and hypertrophy of the left ventricle. Results in inflammatory changes in the vascular walls, which may lead to rupture of the glomerular capillaries.
Bronchiectasis
- Bronchiectasis is abnormal and irreversible dilatation of the bronchi and bronchioles (greater than 2 mm in diameter) secondary to inflammatory weakening of bronchial wall.
- Occur in childhood and early adult life
- Persistent cough with copious amount of foul smelling purulent sputum
Aetiopathogenesis
Bronchial wall destruction is due to:
- Endobronchial obstruction due to foreign body
- Infection due to local obstruction or impaired defence mechanism
Clinical conditions:
- Hereditary and congenital factors
- Obstruction
- Secondary complication
Hereditary and congenital factors:
- Congenital bronchiectasis due to developmental defects
- Cystic fibrosis causing defective secretion resulting in obstruction
- Hereditary immune defiency diseases
- Immotile cilia syndrome- immotile cilia of respiratory tract, sperms causing Kartagener’s syndrome (bronchiectasis, situs inversus and sinusitis) and male infertility
- Allergic bronchial asthma patients
Obstruction:
Localised variety in one part of bronchial system.
Obstruction can be due to
Foreign body
Endobronchial tumors
Hilar lymph nodes
Inflammatory scarring (TB)
Secondary complication:
Necrotizing pneumonia in Staph infection and TB
Morphologic changes
- Affects distal bronchi and bronchioles
- Lower lobes more frequently
- Lungs involved diffusely/segmentally
- Left lower lobe than right
- Pleura fibrotic & thickened adherent to chest wall
C/S lung: Honey-combed appearance
Microscopic examination:
Bronchiole-dilated
Bronchial epithelium-normal, ulcerated, squamous metaplasia
Bronchial wall-infiltration by ac & Ch inflammatory cells,
destruction of muscle, elastic tissue
Lung parenchyma-fibrosis, surrounding tissue pneumonia
Pleura-fibrotic and adherent
Pathology
The branch of medicine dealing with the essential nature of disease, especially changes in body tissues aorgans that cause or are caused by disease. Pathology is the structural and functional manifestations of disease.
Anatomic pathology the anatomical study of changes in the function, structure, or appearance of organs or tissues,including postmortem examinations and the study of biopsy specimens.
Cellular pathology - Cytopathology is a diagnostic technique that examines cells from various body sites to determine the cause or the nature of disease.
Clinical pathology pathology applied to the solution of clinical problems, especially the use of laboratory
methods inclinical diagnosis.
Comparative pathology that which considers human disease processes in comparison with those of other
animals.
Oral pathology that treating of conditions causing or resulting from morbid anatomic or functional changes in thestructures of the mouth.
Surgical pathology the pathology of disease processes that are surgically accessible for diagnosis or treatment.
Hereditary spherocytosis.
Functionally normal cells which are destroyed .in spleen because of the structural abnormality. It is transmitted as an autosomal dominant trait
Congenital hemolytic anemia due to genetically determined abnormal spectrin and ankyrin molecules, leading to defects in red blood cell membrane, causing spherical shape and lack of plasticity
Red blood cells become trapped within spleen and have less than usual 120 day lifespan
Splenic function is normal
Osmotic fragility: increased; basis for diagnostic testing
Description
Firm, deep red tissue, thin capsule, no grossly identifiable malpighian follicles, 100-1000g
Peripheral blood images
Marked congestion in cords
Sinuses appear empty but actually contain ghost red blood cells
May have prominent endothelial lined sinuses, hemosiderin deposition, erythrophagocytosis
Erythema nodosum is the MCC of inflammation of subcutaneous fat (panniculitis).
- it may be associated with tuberculosis, leprosy, certain drugs (sulfonamides), and is commonly a harbinger of coccidioidomycosis and sarcoidosis.
- commonly presents on the lower extremities with exquisitely tender, raised erythematous plaques and nodules.
- self-limited disease.