NEET MDS Lessons
General Pathology
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.
THE PITUITARY GLAND
This is a small, bean-shaped structure that lies at the base of the brain within the confines of the sella turcica. It is connected to the hypothalamus by a "stalk," composed of axons extending from the hypothalamus. The pituitary is composed of two morphologically and functionally distinct components: the anterior lobe (adenohypophysis) and the posterior lobe (neurohypophysis). The adenohypophysis, in H&E stained sections, shows a colorful collection of cells with basophilic, eosinophilic or poorly staining ("chromophobic") cytoplasm.
Fanconi’s syndrome
Characterized by the failure of the proximal renal tubules to resorb amino acids, glucose, and phosphates.
May be inherited or acquired.
Clinical manifestations include
glycosuria, hyperphosphaturia, hypophosphatemia, aminoaciduria, and systemic acidosis.
Varicose Veins
- are abnormally dilated, tortuous veins produced by prolonged increase in intraluminal pressure and loss of vessel wall support.
- The superficial veins of the leg are typically involved
-venous pressures in these sites can be markedly elevated -> venous stasis and pedal edema (simple orthostatic edema)
-Some 10% to 20% of adult males and 25% to 33% of adult females develop lower extremity varicose veins
RISK FACTORS
-> obesity
-> Female gender
-> pregnancy.
-> familial tendency (premature varicosities results from imperfect venous wall development)
Morphology
- wall thinning
- intimal fibrosis in adjacent segments
- spotty medial calcifications (phlebosclerosis)
- Focal intraluminal thrombosis
- venous valve deformities (rolling and shortening)
COMPLICATIONS
- stasis, congestion, edema, pain, and thrombosis
- chronic varicose ulcers
- embolism is very rare.
Anemia (Disorder of Hematopoietic System) - Probably the most common effect of nutritional deficiency. Any factor that decreases hematopoiesis can cause an anemia.
A. Iron deficiency - Widely recognized as the most important cause of anemia, It is indicated that ½ of all pregnant women and infants are affected, as are ~13% of all adult women.
1. Dietary factors - Availability of iron from different food sources and mixtures.
2. Malabsorption – One third of patients with inflammatory bowel disease (IBD) have recurrent anemia and 30% or more of patients who have had partial gastrectomy will develop iron deficiency anemia.
3. Blood loss - Menses, gastrointestinal bleeding
4. Increased demand - Pregnancy, growth in children.
5. Congenital - Atransferrinemia
6. Importance of multiple factors.
7. Pathophysiology - Initially iron is mobilized from reticuloendothelial stores and increased intestinal absorption occurs. Total iron stores are depleted, serum iron levels fall. In severe cases in peripheral blood, the red cells become smaller (microcytic) and their hemoglobin content is reduced (hypochromic).
B. Megaloblastic anemias- Characterized by the presence of abnormal WBCs and RBCs. In severe cases, megaloblasts (abnormal red cell precursors) may be present. These anemias are a consequence of disordered DNA synthesis.
1. Folate deficiency - Can be caused by:
a. Dietary deficiency
b. Malabsorption (celiac disease)
c. Increased demand (pregnancy & lactation)
d. Drugs - methotrexate, anticonvulsants, oral contraceptives, alcoholism.
e. Liver disease
2. Cobalamin (vitamin B12) deficiency - Almost always a secondary disorder that can be caused by:
a. Intrinsic factor deficiency (pernicious anemia due to autoimmune destruction of the gastric mucosa)
b. Malabsorption
3. Pyridoxine (vitamin B6) deficiency- most commonly associated with alcoholism.
C. Other factors known to be frequently associated with anemia would include protein-calorie malnutrition, vitamin C deficiency, and pyridoxine deficiency (usually associated with alcoholism).
D. Other anemias not particularly associated with nutritional disease would include hemolytic anemia
(decreased red cell life span) and aplastic anemia (failure of marrow to produce new cells).
Lymphangitis
is the acute inflammation due to bacterial infections spread into the lymphatics most common are group A β-hemolytic streptococci.
lymphatics are dilated and filled with an exudate of neutrophils and monocytes.
red, painful subcutaneous streaks (the inflamed lymphatics), with painful enlargement of the draining lymph nodes (acute lymphadenitis).
subsequent passage into the venous circulation can result in bacteremia or sepsis.
Parasitic
1. Leishmania produce 3 kinds of disease in man
- visceral leishmaniasis (kala azar) due to Leishmania donovani complex,
- cutaneous leishmaniasis due to Leishmania tropica complex, and
- mucocutaneous leishmaniasis due to Leishmania braziliensis.
- cutaneous (Oriental sore) and mucocutansous leishmaniasis limit themselves to the skinalone (ulcers) in the former disease and skin plus mucous membranes in the latter variant.
- the diagnosis of cutaneous or mucocutaneous leishmaniasis is made by biopsy, culture, skin test, or serologic tests
- the laboratory diagnosis of visceral leishmaniasis is made by performing a bone marrow aspirate and finding the leishmanial forms in macrophages, by culture, by hamster inoculation, or by serology.
- recovery from the cutaneous form incurs immunity.
- treatment: stibogluconate