NEET MDS Lessons
General Pathology
STOMACH
Congenital malformations
1. Pyloric stenosis
Clinical features. Projectile vomiting 3-4 weeks after birth associated with a palpable "olive" mass in the epigastric region is observed.
Pathology shows hypertrophy of the muscularis of the pylorus and failure to relax.
2. Diaphragmatic hernias are due to weakness in or absence of parts of the diaphragm, allowing herniation of the abdominal contents into the thorax.
Inflammation
1. Acute gastritis (erosive)
Etiology. Alcohol, aspirin and other NSAIDs, smoking, shock, steroids, and uremia may all cause disruption of the mucosal barrier, leading to inflammation.
Clinical features. Patients experience heartburn, epigastric pain, nausea, vomiting, hematemesis, and even melena.
2. Chronic gastritis (nonerosive) may lead to atrophic mucosa with lymphocytic infiltration.
Types
(1) Fundal (Type A) gastritis is often autoimmune in origin. It is the type associated with pernicious anemia and, therefore, achlorhydria and intrinsic factor deficiency.
(2) Antral (Type B) gastritis is most commonly caused by Helicobacter pylori and is the most common form of chronic gastritis in the U.S. H. pylori is also responsible for proximal duodenitis in regions of gastric metaplasia.
Clinical features. The patient may be asymptomatic or suffer epigastric pain, nausea, vomiting, and bleeding. Gastritis may predispose to peptic ulcer disease, probably related to H. pylori infection.
3. Peptic ulcers
Peptic ulcers are usually chronic, isolated ulcers observed in areas bathed by pepsin and HCI; they are the result of mucosal breakdown
Common locations are the proximal duodenum, the stomach, and the esophagus, often in areas of Barrett's esophagus.
Etiology. There are several important etiologic factors.
Duodenal ulcers occur predominantly in patients with excess acid secretion, while gastric ulcers usually occur in patients with lower than average acid secretion.
Other predisposing conditions include smoking, cirrhosis, pancreatitis, hyperparathyroidism, and H. pylori infection. Aspirin, steroids, and NSAlDs are known to be assoicated with peptic ulcer disease. Next to H. pylori colonization, aspirin or NSAID ingestion is the most common cause of peptic ulcer.
Clinical features. Patients experience episodic epigastric pain. Duodenal and most gastric ulcers are relieved by food or antacids. Approximately one-fifth of gastric ulcer patients get no relief from eating or experience pain again within 30 minutes.
Pathology. Benign peptic ulcers are well-circumscribed lesions with a loss of the mucosa, underlying scarring, and sharp walls.
Complications include hemorrhage, perforation, obstruction, and pain. Duodenal ulcers do not become malignant .Gastric ulcers do so only rarely; those found to be ma1ignant likely originated as a cancer that ulcerated.
Diagnosis is made by upper gastrointestinal Series , endoscopy, and biopsy to rule out malignancy or to demonstrate the presence of H. pylori.
4. Stress ulcers
are superficial mucosal ulcers of the stomach or duodenum or both. Stress may be induced by burns, sepsis shock, trauma, or increased intracranial pressure.
Tumors
1. Benign
a. Leiomyoma, often multiple, is the most common benign neoplasm of the stomach. Clinical features include bleeding, pain, and iron deficiency anemia.
b. Gastric polyps are due to proliferation of the mucosal epithelium.
2. Malignant tumors
a. Carcinoma
Etiology. Primary factors include genetic predisposition and diet; other factors include hypochlorhydria, pernicious anemia, atrophic gastritis, adenomatous polyps, and exposure to nitrosamines. H. pylori are also implicated.
Clinical features. Stomach cancer is usually asymptomatic until late, then presents with anorexia, weight loss, anemia, epigastric pain, and melena. Virchow's node is a common site of metastasis.
Pathology. Symptomatic late gastric carcinoma may be expanding or infiltrative. In both cases the prognosis is poor (approximately 10% 5-year survival), and metastases are frequently present at the time of diagnosis.
Adenocarcinomas are most common.
b. Gastrointestinal lymphomas may be primary In the gastrointestinal tract as solitary masses.
c. Sarcoma is a rare, large, ulcerating mass that extends into the lumen.
d. Metastatic carcinoma. Krukenberg's tumor is an ovaria metastasis from a gastric carcinoma.
e. Kaposi's sarcoma. The stomach is the most commonly involved GI organ in Kaposi's sarcoma. It primarily occurs in homosexual men, appearing as hemorrhagic polypoid, umbilicated nodular lesions, typically in a submucosal location. It rarely causes symptoms
Erythema multiforme is a hypersensitivity reaction to an infection (Mycoplasma), drugs or various autoimmune diseases.
- probable immunologic disease
- lesions vary from erythematous macules, papules, or vesicles.
- papular lesions frequently look like a target with a pale central area.
- extensive erythema multiforme in children is called Stevens-Johnson syndrome, where there is extensive skin and mucous membrane involvement with fever and respiratory symptoms.
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.
G-6 PD Deficiency
Occurs in Negroes, Mediterranean races, India and far East. It confers a protection Against falciparum malaria.
It is transmitted as X-linked trait of intermediate dominance (variable effect in homozygous females).
Haemolysis may be induced by :
• Primaquin and other anti malarials.
• Other drugs like chloramphenicol , analgesics, antitubercular drugs etc.
• Infections.
• Ingestion of Vicia faba bean (favism).
• Diabetic acidosis
THROMBOPHLEBITIS AND PHLEBOTHROMBOSIS
- The deep leg veins account for more than 90% of cases (DVT)
- the most important clinical predispositions are: congestive heart failure, neoplasia, pregnancy, obesity, the postoperative state, and prolonged bed rest or immobilization
- local manifestations: distal edema, cyanosis, superficial vein dilation, heat, tenderness, redness, swelling, and pain
- migratory thrombophlebitis (Trousseau sign): hypercoagulability occurs as a paraneoplastic syndrome related to tumor elaboration of procoagulant factors
Nevus
1. Commonly known as moles.
2. A benign, pigmented tumor of melanocytes, found deep within connective tissue.
3. Types of skin nevi:
a. Junctional nevus—found in the epidermis.
It is the only type of nevus that may be considered to be premalignant.
b. Compound nevus—found in both the epidermis and underlying dermis.
c. Intraepidermal nevus—found in the dermis.
Agranulocytosis. Severe neutropenia with symptoms of infective lesions.
Drugs. are an important cause and the effect may be due to .
-Direct toxic effect.
-Hypersensitivity.
Some of the 'high risk drugs are.
-Amidopyrine.
-Antithyroid drugs.
-Chlorpromazine, mapazine.
-Antimetabolites and other drugs causing pancytopenia.
Bloodpicture: Neutropenia with toxic granules in neutrophils. Marrow shows decrease in granulocyte precursors with toxic granules in them.