NEET MDS Lessons
General Pathology
Neutropenia: Neutropenia is an abnormally low number of neutrophils
Causes
-Typhoid, paratyphoid. .
-Viral and ricketseal infections.
-Malaria, Kala azar.
-Hypersplenism.
-Aplastic and megaloblastic anaemia.
-Marrow infiltration by malignancies, lymphomas etc.
-SLE.
Congestive heart failure (CHF)
A. Left-sided CHF
1. May result from nearly any heart disease affecting the left ventricle (e.g., ischemic heart disease, hypertension, valvular disease).
2. Common signs and symptoms include:
a. Dyspnea (shortness of breath) exacerbated by exertion.
b. Paroxysmal nocturnal dyspnea.
c. Orthopnea.
d. Tachypnea.
e. Pleural effusion.
f. Consequences include pulmonary edema.
B. Right-sided CHF
1. The most common cause of right heart failure is left heart failure. It uncommonly occurs in isolation. Other causes include left-sided lesions (mitral stenosis), pulmonary hypertension, cardiomyopathy, and tricuspid or pulmonary valvular disease.
2. Frequently presents with peripheral edema, especially in the ankles and feet (i.e., dependent edema), enlarged liver or spleen, and distention of the neck veins.
Hypopituitarism
Hypopituitarism is caused by
1. Loss of the anterior pituitary parenchyma
a. congenital
b. acquired
2. Disorders of the hypothalamus e.g. tumors; these interfere with the delivery of pituitary hormone-releasing factors from the hypothalamus.
Most cases of anterior pituitary hypofunction are caused by the following:
1. Nonfunctioning pituitary adenomas
2. Ischemic necrosis of the anterior pituitary is an important cause of pituitary insufficiency. This requires destruction of 75% of the anterior pituitary.
Causes include
a. Sheehan syndrome, refers to postpartum necrosis of the anterior pituitary, and is the most cause. During pregnancy the anterior pituitary enlarges considerably because of an increase in the size and number of prolactin-secreting cells. However, this physiologic enlargement of the gland is not accompanied by an increase in blood supply. The enlarged gland is therefore vulnerable to ischemic injury, especially in women who develop significant hemorrhage and hypotension during the peripartum period. The posterior pituitary is usually not affected.
b. Disseminated intravascular coagulation
c. Sickle cell anemia
d. Elevated intracranial pressure
e. Traumatic injury
f. Shock states
3. Iatrogenic i.e. surgical removal or radiation-induced destruction
4. Inflammatory lesions such as sarcoidosis or tuberculosis
5. Metastatic neoplasms involving the pituitary.
6. Mutations affecting the pituitary transcription factor Pit-1
Children can develop growth failure (pituitary dwarfism) as a result of growth hormone deficiency.
Gonadotropin or gonadotropin-releasing hormone (GnRH) deficiency leads to amenorrhea and infertility in women and decreased libido, impotence, and loss of pubic and axillary hair in men. TSH and ACTH deficiencies result in symptoms of hypothyroidism and hypoadrenalism. Prolactin deficiency results in failure of postpartum lactation.
German measles (rubella)
- sometimes called "three day measles".
- incubation 14-21 days; infectious 7 days before the rash and 14 days after the onset of the rash.
- in adults, rubella present with fever, headache, and painful postauricular Lymphadenopathy 1 to 2 days prior to the onset of rash, while in children, the rash is usually the first sign.
- rash (vasculitis) consists of tiny red to pink macules (not raised) that begins on the head and spreads downwards and disappears over the ensuing 1-3 days; rash tends to become confluent.
- 1/3rd of young women develop arthritis due to immune-complexes.
- splenomegaly (50%)
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.
1. Pyogenic liver abscesses may be caused by E. coli, Klebsiella, Streptococcus, Staphylococcus, Bacteroides, Pseudomonas, and fungi.
Parasitic infections
1. Schistosomiasis is caused by different organisms in different parts of the world.
a. Clinical features include splenomegaly, portal hypertension, and ascites. Lesions are caused by the immune response to ova.
2. Amebiasis is caused by Entamoeba histolytica.
a. Clinical features include bloody diarrhea, pain, fever, jaundice, and hepatomegaly.
Drug-induced liver damage may be caused by agents that are direct hepatotoxins, such as carbon tetrachloride, acetaminophen, methotrexate, anabolic steroids, and oral contraceptive pills.
Keloids
1. Characterized by a progressively enlarging scar.
2. Caused by an abnormal accumulation of collagen at the site of injury.
3. More common in African-Americans.