Nephritic syndrome

Characterized by inflammatory rupture of the glomerular capillaries, leaking blood into the urinary space.

Classic presentation: poststreptococcal glomerulonephritis. It occurs after a group A, β–hemolytic Streptococcus infection (e.g., strep throat.)

Caused by autoantibodies forming immune complexes in the glomerulus.

Clinical manifestations: 

oliguria, hematuria, hypertension, edema, and azotemia (increased concentrations of serum urea nitrogen
and creatine).

Congenital heart defect
Congenital heart defects can be broadly categorised into two groups,
o    acyanotic heart defects ('pink' babies) :

 An acyanotic heart defect is any heart defect of a group of structural congenital heart defects,  approximately 75% of all congenital heart defects.
 It can be subdivided into two groups depending on whether there is shunting of the blood from the left vasculature to the right (left to right shunt) or no shunting at all.

Left to right shunting heart defects include 
- ventricular septal defect or VSD (30% of all congenital heart defects),
- persistent ductus arteriosus or PDA, 
- atrial septal defect or ASD, 
- atrioventricular septal defect or AVSD.

Acyanotic heart defects without shunting include 
- pulmonary stenosis, a narrowing of the pulmonary valve, 
- aortic stenosis 
- coarctation of the aorta.

cyanotic heart defects ('blue' babies). 
obstructive heart defects

 cyanotic heart defect is a group-type of congenital heart defect. These defects account for about 25% of all congenital heart defects. The patient appears blue, or cyanotic, due to deoxygenated blood in the systemic circulation. This occurs due to either a right to left or a bidirectional shunt, allowing significant proportions of the blood to bypass the pulmonary vascular bed; or lack of normal shunting, preventing oxygenated blood from exiting the cardiac-pulmonary system (as with transposition of the great arteries).

Defects in this group include 
hypoplastic left heart syndrome,
tetralogy of Fallot, 
transposition of the great arteries, 
tricuspid atresia, 
pulmonary atresia, 
persistent truncus arteriosus.
 

Hepatitis D virus—can only infect cells previously infected with hepatitis B. 
 Delta hepatitis (HDV) is associated with a 35-nm RNA virus composed of a delta antigen-bearing core surrounded by HBV's Ag coat;

HDV requires HBV for replication.

Delta hepatitis can cause quiescent HBV states to suddenly worsened . Its transmission is the same as that of HBV.
 
 Hepatitis E virus—a high mortality rate in infected pregnant women.

Hepatitis E (HEV) is caused by a single-stranded RNA virus. The disease is typically self-limited and does not evolve into chronic hepatitis; it may, however, be cholestatic.

Pregnant women may develop fulminant disease.

Transmission is by the fecal oral route.

HEV occurs mainly in India, Nepal, Pakistan, and Southeast Asia.
 

ESOPHAGUS Pathology

Congenital malformations 
1. A tracheoesophageal fistula (the most prevalent esophageal anomaly) occurs most commonly as an upper esophageal blind pouch with a fistula between the lower segment of the esophagus and the trachea. It is associated with hydramnios, congenital heart disease, and other gastrointestinal malformation. 

2. Esophageal atresia is associated with VATER syndrome (vertebra1 defects, anal atresia, tracheoesophageal fistula, and renal dysplasia)

3. Stenosis refers to a narrowed esophagus with a small lumen.  lt may be congenital or acquired, e.g., through trauma or inflammation. 

Inflammatory disorders 

Esophagitis 

most often involves the lower half of the esophagus.  Caused by the reflux of gastric contents (juices) into the lower esophagus. One of the most common GI disorders.

Clinical features. 

Patients experience substernal burning  associated with regurgitation, mild anemia, dysphagia,  hematemesis, and melena. Esophagitis may predispose to esophageal cancer. 

Etiology

- Reflux esophagitis is due to an incompetent lower esophageal sphincter that permits reflux of gastric juice into the lower esophagus. 
- Irritants such as citric acid, hot liquids, alcohol, smoking, corrosive chemicals, and certain drugs, such as tetracycline, may provoke inflammation. 
- Infectious etiologies include herpes, CMV, and C. albicans. The immunocompromised host is particularly susceptible to infectious esophagitis. 
Although chronic or severe reflux disease is uncommon, consequences of these conditions can lead to Barrett’s esophagus, development of a stricture, or hemorrhage.

Pathology

-Grossly, there is hyperemia, edema, inflammation, and superficial necrosis. 

Complications include ulceration, bleeding, stenosis, and squamous carcinoma. 

Treatment: diet control, antacids, and medications that decrease the production of gastric acid (e.g., H blockers).

Barrett's esophagus, 

gastric or intestinal columnar epithelium replaces normal squamous epithelium in response to  chronic reflux.- A complication of chronic gastroesophageal reflux disease.
- Histologic findings include the replacement of squamous epithelium with metaplastic columnar epithelium.
- Complications include increased incidence of esophageal adenocarcinoma, stricture formation, or hemorrhage (ulceration).

 Motor disorders. 

Normal motor function requires effective peristalsis and relaxation of the lower esophageal sphincter. 

Achalasia is a lack of relaxation of the lower esophageal sphincter (LES), which may be associated with aperistalsis of the esophagus and increased basal tone of the LES. 

Clinical features. Achalasia occurs most commonly between the ages of 30 and 50. Typical symptoms are dysphagia, regurgitation, aspiration, and chest pain. The lack of motility promotes stagnation and predisposes to carcinoma. 

Hiatal hernia is the herniation of the abdominal esophagus, the stomach, or both, through the esophageal hiatus in the  diaphragm.

Scleroderma is a collagen vascular disease, seen primarily in women, that causes subcutaneous fibrosis and widespread  degenerative changes. (A mild variant is known as CREST syndrome which stands for calcinosis. raynaud's phenomenon , esophageal dysfunction, sclerodactyly and telengectseia. esophagus is the most frequently involved region of the gastrointestinal tract.

Clinical features are mainly dysphagia and heartburn due to reflux oesophagitis caused by aperlistalsis and incompetent LES. 

Rings and webs 

1. Webs are mucosal folds in the upper esophagus above the aortic arch. 
2. Schatzki rings are mucosal rings at the squamocolumnarjunction below the aortic arch.
3. Plummer Vinson Syndrome consist of triad of dysphagia, atrophic glossitis, and anemia. Webs are found in the upper esophagus. The syndrome is associated specifically with iron deficiency anemia and sometimes hypochlorhydria. Patients are at increased risk for carcinoma of the pharynx or esophagus. 

Mallory-Weiss syndrome
Mallory-Weiss tears refers to small mucosal tears at the gastroesophageal junction secondary to recurrent forceful vomiting. The tears occur along the long axis an result in hematemesis (sometimes massive).

- Characterized by lacerations (tears) in the esophagus.
- Most commonly occurs from vomiting (alcoholics).
- A related condition, known as Boerhaave syndrome, occurs when the esophagus ruptures, causing massive upper GI hemorrhage.

Esophageal varices
- The formation of varices (collateral channels) occurs from portal hypertension.
Causes of portal hypertension include blockage of the portal vein or liver disease (cirrhosis).
- Rupture of esophageal varices results in massive hemorrhage into the esophagus and hematemesis.
- Common in patients with liver cirrhosis.

Diverticula 
are sac-like protrusions of one or more layers of  pharyngeal or esophageal wall. 

Tumors 
- Benign tumors are rare. 
- Carcinoma of the esophagus most commonly occurs after 50 and has a male:female ratio of 4.1. 

Etiology: alcohal ingestion, smoking, nitrosamines in food, achalasia , web ring, Barrettes esophagus, and deficiencies of vitamins A and C , riboflavin, and some trace minerals

Clinical features include dysphagia (first to solids), retrosternal pain, anorexia, weight loss, melena, and symptoms secondary to metastases. 

Pathology 

- 50% occur in the middle third of the esophagus, 30% in the lower third, and 20% in the upper third. Most esophageal cancers are squamous cell carcinomas. 
Adenocarcinomas arise mostly out of Barrett's esophagus.

Prognosis

is poor. Fewer than 10% of patients survive 5 years, usually because diagnosis is made at a late stage. The  most common sites of metastasis are the liver and lung. The combination of cigarette smoking and alcohol is particularly causative for esophageal cancer (over l00%  risk compared to nondrinkers/nonsmokers). 

Chronic hepatitis

Chronic hepatitis occurs in 5%-10% of HBV infections and in well over 50% of HCV; it does not occur in HAV. Most chronic disease is due to chronic persistent hepatitis. The chronic form  is more likely to occur in the very old or very young, in males, in immunocompromised hosts, in Down's syndrome, and in dialysis patients.

a. Chronic persistent hepatitis is a benign, self-limited disease with a prolonged recovery. Patients are asymptomatic except for elevated transaminases. 

b. Chronic active hepatitis features chronic inflammation with hepatocyte destruction, resulting in cirrhosis and liver failure. 
(1) Etiology. HBV, HCV, HDV, drug toxicity, Wilson's disease, alcohol, a,-antitrypsin deficiency, and autoimmune  hepatitis are common etiologies.
(2) Clinical features may include fatigue, fever, malaise, anorexia, and elevated liver function tests. 
(3) Diagnosis is made by liver biopsy.

8. Carrier state for HBV and HCV may be either asymptomatic or with liver disease; in the latter case, the patient has elevate transaminases.
a. Incidence is most common in immunodeficient, drug addicted, Down's syndrome, and dialysis patients. 
b. Pathology of asymptomatic carriers shows "ground-glass"" hepatocytes with finely granular eosinophilic cytoplasm.

Pemphigus
1. Ulcerative lesions on the skin and oral mucosa.
2. An autoimmune disease in which patients have autoantibodies against hemidemosomal attachment of epidermis cells.
3. Histologically characterized by acantholysis, in which epidermal cells appear to detach and separate from each other, as seen by Tzanck smears.
4. Can be life-threatening if untreated.
5. A positive Nikolsky sign is observed.
Because of sloughing of the epidermis, a red blister forms after pressure is applied to affected skin.
6. Treatment: corticosteroids.