NEET MDS Lessons
General Pathology
Huntington’s disease
a. Causes dementia.
b. Genetic transmission: autosomal dominant.
c. Characterized by the degeneration of striatal neurons, affecting cortical and basal ganglia function.
d. Clinically, the disease affects both movement and cognition and is ultimately fatal.
Pulmonary embolism
A pulmonary embolism (thromboembolism) occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs.
Clinical presentation
Signs of PE are sudden-onset dyspnea (shortness of breath, 73%), tachypnea (rapid breathing, 70%), chest pain of "pleuritic" nature (worsened by breathing, 66%), cough (37%), hemoptysis (coughing up blood, 13%), and in severe cases, cyanosis, tachycardia (rapid heart rate), hypotension, shock, loss of consciousness, and death. Although most cases have no clinical evidence of deep venous thrombosis in the legs, findings that indicate this may aid in the diagnosis.
Diagnosis
The gold standard for diagnosing pulmonary embolism (PE) is pulmonary angiography
An electrocardiogram may show signs of right heart strain or acute cor pulmonale in cases of large PEs
In massive PE, dysfunction of the right side of the heart can be seen on echocardiography, an indication that the pulmonary artery is severely obstructed and the heart is unable to match the pressure.
Treatment
Acutely, supportive treatments, such as oxygen or analgesia
In most cases, anticoagulant therapy is the mainstay of treatment. Heparin or low molecular weight heparins are administered initially, while warfarin therapy is given
A dermatofibroma is a benign tumor of the dermis, MC located on the lower extremity, where it has a nodular, pigmented appearance.
- composed of benign histiocytes.
Bronchitis
Bronchitis is an obstructive pulmonary disease characterized by inflammation of the bronchi of the lungs
Signs and symptoms
persistent cough that produces sputum
shortness of breath (dyspnea) on exertion
hypercapnia
insufficient oxygenation of the blood hypoxemia leading to cynosis
Severe chronic bronchitis will commonly lead to cor pulmonale and heart failure.
Pathology
an increase in the number of goblet cells with mucus blocking the airway clusters of pigmented alveolar macrophages
the presence of inflammatory cells (e.g. neutrophils) scarring (fibrosis) of the walls of the bronchioles
Diagnosis
- decreased intensity of breath sounds (rhonchi) and extended expiration.
- a sputum culture has pathogenic microorganisms
- a chest x-ray that reveals hyperinflation and increased bronchovascular markings
- a pulmonary function test that shows an increase in the lung's residual volume and a decreased vital capacity
Pathophysiology
- The initiating event in developing bronchitis appears to be chronic irritation due to inhalation of certain chemicals
- earliest clinical feature of bronchitis is increased secretion of mucus by submucousal glands of the trachea and bronchi
- Damage caused by irritation of the airways leads to inflammation and infiltration of the lung tissue by neutrophils
- The neutrophils release substances that promote mucousal hypersecretion
- As bronchitis persists to become chronic bronchitis, a substantial increase in the number of goblet cells in the small airways is seen
- The role of infection in the pathogenesis of chronic bronchitis appears to be secondary.
Treatment
Quit smoking, Oxygen therapy, bronchodilator drugs
Prognosis
Pulmonary hypertension, cor pulmonale, and chronic respiratory failure are possible complications of chronic bronchitis
In severe chronic bronchitis is poor
FUNGAL INFECTION
Mucormycosis (Zygomycosis; Phycomycosis)
Infection with tissue invasion by broad, nonseptate, irregularly shaped hyphae of diverse fungal species, including Rhizopus, Rhizomucor, Absidia, and Basidiobolus.
Infection is most common in immunosuppressed persons, in patients with poorly controlled diabetes, and in patients receiving the iron-chelating drug desferrioxamine.
Symptoms and Signs
Rhinocerebral mucormycosis is the most common form, but primary cutaneous, pulmonary, or GI lesions sometimes develop, and hematogenous dissemination to other sites can occur. Rhinocerebral infections are usually fulminant and frequently fatal. Necrotic lesions usually appear on the nasal mucosa or sometimes the palate.
Biochemical examination
This is a method by which the metabolic disturbances of disease are investigated by assay of various normal and abnormal compounds in the blood, urine, etc.
Lysosomal (lipid) storage diseases
- Genetic transmission: autosomal recessive.
- This group of diseases is characterized by a deficiency of a particular lysosomal enzyme. This results in an accumulation of the metabolite, which would have otherwise been degraded by the presence of normal levels of this specific enzyme.
Diseases include:
Gaucher’s disease
(1) Deficient enzyme: glucocerebrosidase.
(2) Metabolite that accumulates: glucocerebroside.
(3) Important cells affected: macrophages.
Tay-Sachs disease
(1) Deficient enzyme: hexosaminidase A.
(2) Metabolite that accumulates: GM2 ganglioside.
(3) Important cells affected: neurons.
(4) Symptoms include motor and mental deterioration, blindness, and dementia.
(5) Common in the Ashkenazi Jews.
Niemann-Pick disease
(1) Deficient enzyme: sphingomyelinase.
(2) Metabolite that accumulates: sphingomyelin.
(3) Important cells affected: neurons.