NEET MDS Lessons
General Pathology
Actinic keratosis
1. Dry, scaly plaques with an erythematous base.
2. Similar to actinic cheilosis, which occurs along the vermilion border of the lower lip.
3. Caused by sun damage to the skin.
4. Dysplastic lesion, may be premalignant.
Lymphocytosis:
Causes
-Infections in children and the neutropenic infections in adults.
-Lymphocytic leukaemia.
-Infectious mononucleosis.
-Toxdplasmosis.
-Myast'henia gravis.
Pulmonary edema
Pulmonary edema is swelling and/or fluid accumulation in the lungs. It leads to impaired gas exchange and may cause respiratory failure.
Signs and symptoms
Symptoms of pulmonary edema include difficulty breathing, coughing up blood, excessive sweating, anxiety and pale skin. If left untreated, it can lead to death, generally due to its main complication of acute respiratory distress syndrome.
Diagnosis
physical examination: end-inspiratory crackles during auscultation (listening to the breathing through a stethoscope) can be due to pulmonary edema. The diagnosis is confirmed on X-ray of the lungs, which shows increased vascular filling and fluid in the alveolar walls.
Low oxygen saturation and disturbed arterial blood gas readings may strengthen the diagnosis
Causes
Cardiogenic causes:
- Heart failure
- Tachy- or bradyarrhythmias
- Severe heart attack
- Hypertensive crisis
- Excess body fluids, e.g. from kidney failure
- Pericardial effusion with tamponade
Non-cardiogenic causes, or ARDS (acute respiratory distress syndrome):
- Inhalation of toxic gases
- Multiple blood transfusions
- Severe infection
- Pulmonary contusion, i.e. high-energy trauma
- Multitrauma, i.e. severe car accident
- Neurogenic, i.e. cerebrovascular accident (CVA)
- Aspiration, i.e. gastric fluid or in case of drowning
- Certain types of medication
- Upper airway obstruction
- Reexpansion, i.e. postpneumonectomy or large volume thoracentesis
- Reperfusion injury, i.e. postpulmonary thromboendartectomy or lung transplantation
- Lack of proper altitude acclimatization.
Treatment
When circulatory causes have led to pulmonary edema, treatment with loop diuretics, such as furosemide or bumetanide, is the mainstay of therapy. Secondly, one can start with noninvasive ventilation. Other useful treatments include glyceryl trinitrate, CPAP and oxygen.
Lymphopenia:
Causes
-As part of pancytopenia.
-Steroid administration.
PRIMARY LYMPHEDEMA
can occur as:
1- A congenital defect, resulting from lymphatic agenesis or hypoplasia.
2- Secondary or obstructive lymphedema
- blockage of a previously normal lymphatic; e.g. Malignant tumors
- Surgical procedures that remove lymph nodes
- Postirradiation
- Fibrosis
- Filariasis
- Postinflammatory thrombosis and scarring
Osteonecrosis (Avascular Necrosis)
Ischemic necrosis with resultant bone infarction occurs mostly due to fracture or after corticosteroid use. Microscopically, dead bon trabevulae (characterized by empty lacunae) are interspersed with areas of fat necrosis.
The cortex is usually not affected because of collateral blood supply; in subchondral infarcts, the overlying articular cartilage also remains viable because the synovial fluid can provide nutritional support. With time, osteoclasts can resorb many of the necrotic bony trabeculae; any dead bone fragments that remain act as scaffolds for new bone formation, a process called creeping substitution.
Symptoms depend on the size and location of injury. Subchondral infarcts often collapse and can lead to severe osteoarthritis.
Wilson’s disease
Caused by a decrease in ceruloplasmin, a serum protein that binds copper, resulting in metastatic copper deposits.
Common organs affected include:
(1) Liver, leading to cirrhosis.
(2) Basal ganglia.
(3) Cornea, where Kayser-Fleischer rings (greenish rings around the cornea) are observed.