Cholangitis

Cholangitis is inflammation of the bile ducts. 
1. It is usually associated with biliary duct obstruction by gallstones or carcinoma, which leads to infection with enteric organisms. This results in purulent exudation within the bile ducts and bile stasis. 
2. Clinically, cholangitis presents with jaundice, fever, chills. leukocytosis, and right upper quadrant pain
 

Respiratory Viral Diseases

Respiratory viral infections cause acute local and systemic illnesses. The common cold, influenza, pharyngitis, laryngitis (including croup), and tracheobronchitis are common.

An acute, usually afebrile, viral infection of the respiratory tract, with inflammation in any or all airways, including the nose, paranasal sinuses, throat, larynx, and sometimes the trachea and bronchi.

Etiology and Epidemiology

Picornaviruses, especially rhinoviruses and certain echoviruses and coxsackieviruses, cause the common cold. About 30 to 50% of all colds are caused by one of the > 100 serotypes of rhinoviruses.

Symptoms and Signs

Clinical symptoms and signs are nonspecific.

After an incubation period of 24 to 72 h, onset is abrupt, with a burning sensation in the nose or throat, followed by sneezing, rhinorrhea, and malaise.

Characteristically, fever is not present, particularly with a rhinovirus or coronavirus. Pharyngitis usually develops early; laryngitis and tracheobronchitis vary by person and causative agent. Nasal secretions are watery and profuse during the first days, but become more mucoid and purulent.

Cough is usually mild but often lasts into the 2nd wk.

Thyroid goitres

A goitre is any enlargement of part or whole of the thyroid gland. There are two types:
1. Toxic goitre, i.e. goitre associated with thyrotoxicosis.
2. Non-toxic goitre, i.e. goitre associated with  normal or reduced levels of thyroid hormones.

Toxic goitre
Graves disease
This is the most common cause of toxic goitre 

Toxic multinodular goitre
This results from the development of hyperthyroidism in a multinodular goitre 

Non-toxic goitres
Diffuse non-toxic goitre (simple goitre)

This diffuse enlargement of the thyroid gland is classified into:

Endemic goitre—due to iodine deficiency. Endemic goiter occurs in geographic areas (typically mountainous)) where the soil, water, and food supply contain little iodine. The term endemic is used when goiters are present in more than 10% of the population in a given region. With increasing availability of dietary iodine supplementation, the frequency and severity of endemic goiter have declined significantly. Sporadic goiter is less common than endemic goiter. The condition is more common in females than in males, with a peak incidence in puberty or young adult life, when there is an
increased physiologic demand for T4.

Sporadic goitre—caused by goitrogenic agents (substances that induce goitre formation) or familial in origin. Examples of goitrogenic agents include certain cabbage species, because of their thiourea content, and specific drugs or chemicals, such as iodide, paraminosalicylic acid and drugs used in the treatment of thyrotoxicosis. Familial cases show inherited autosomal recessive traits, which interfere with hormone synthesis via various enzyme pathways (these are dyshormonogenic goitres). 
Hereditary enzymatic defects interfering with thyroid hormone synthesis (dyshormonogenetic goiter).

Physiological goitre—enlargement of the thyroid gland in females during puberty or pregnancy; the reason is unclear.

Multinodular goitre

This is the most common cause of thyroid enlargement and is seen particularly in the elderly (nearly all simple goitres eventually become multinodular). The exact aetiology is uncertain but it may represent an uneven responsiveness of various parts of the thyroid to fluctuating TSH levels over a period of many years.

Morphological features are:

• Irregular hyperplastic enlargement of the entire thyroid gland due to the development of wellcircumscribed nodules of varying size.
• Larger nodules filled with brown, gelatinous colloid; consequently, it is often termed multinodular colloid goitres.

Clinical features 

- A large neck mass, goiters may also cause airway obstruction, dysphagia, and compression of large vessels in the neck and upper thorax.
 - A hyperfunctioning ("toxic") nodule may develop within a long-standing goiter, resulting in hyperthyroidism. This condition is not accompanied by the infiltrative ophthalmopathy and dermopathy. 
 - Less commonly, there may be hypothyroidism.

Hepatitis C virus.

 It is most often mild and anicteric but occasionally severe with fulminant hepatic failure. It is caused an RNA virus, which may be transmitted parenterally (a cause of post-transfusion hepatitis); the route of transmission undetermined in 40%-50% of cases
a. 90% of blood transfusion-related hepatitis is caused by hepatitis C.
b. 50% progress to chronic disease.
c. Increased risk for hepatocellular carcinoma.

d. Incubation period: ranges from 2 to 26 weeks, but averages 8 weeks.
-  Antibody is detected by enzyme-linked immunosorbent,assay (ELISA). The incubation period is between 2 and weeks with peak onset of illness 6-8 weeks after infection 
- Most patients progress to chronic liver disease, specifically chronic persistent hepatitis or chronic active hepatitis 
- Cirrhosis is common in patients with chronic active hepatitis and occurs in 20%-25% of infected patients. HCV is also associated with hepatocellular carcinoma.

e. Treatment and prevention: α-interferon is used to treat chronic hepatitis C. There is currently no vaccine available.

Posterior Pituitary Syndromes 

The posterior pituitary, or neurohypophysis, is composed of modified glial cells (termed pituicytes) and axonal processes extending from nerve cell bodies in the hypothalamus. The hypothalamic neurons produce two peptides: antidiuretic hormone (ADH) and oxytocin that are stored in axon terminals in the neurohypophysis.

The clinically important posterior pituitary syndromes involve ADH production and include  
1. Diabetes insipidus and 
2. Inappropriate secretion of high levels of ADH.  

- ADH is released into the general circulation in response to increased plasma oncotic pressure & left atrial distention. 
- It acts on the renal collecting tubules to increase the resorption of free water. 
- ADH deficiency causes  diabetes insipidus, a condition characterized by polyuria. If the cause is related to ADH Diabetes insipidus from - - ADH deficiency is designated as central, to differentiate it from nephrogenic diabetes insipidus due to renal tubular unresponsiveness to circulating ADH. 
- The clinical manifestations of both diseases are similar and include the excretion of large volumes of dilute urine with low specific gravity. Serum sodium and osmolality are increased as a result of excessive renal loss of free water, resulting in thirst and polydipsia. 

- ADH excess causes resorption of excessive amounts of free water, with resultant hyponatremia. 
- The most common causes of the syndrome include the secretion of ectopic ADH by malignant neoplasms (particularly small-cell carcinomas of the lung), and local injury to the hypothalamus and/or neurohypophysis. 

- The clinical manifestations are dominated by hyponatremia, cerebral edema, and resultant neurologic dysfunction.

Acute viral hepatitis
Clinical features. Acute viral hepatitis may be icteric or anicteric. Symptoms include malaise, anorexia, fever, nausea, upper abdominal pain, and hepatomegaly, followed by jaundice, putty-colored stools, and dark urine.
In HBV, patients may have urticaria, arthralgias, arthritis, vasculitis, and glomerulonephritis (because of circulating immune complexes). Blood tests show elevated serum bilirubin (if icteric), elevated transaminases, and alkaline phosphatase.
The acute illness usually lasts 4-6 weeks. 

Pathology 

(1) Grossly, there is an enlarged liver with a tense capsule. 
(2) Microscopically, there is ballooning degeneration of hepatocytes and liver cell necrosis.