Seborrheic keratosis
1. A round, brown-colored, flat wart.
2. Most often seen in middle-aged to older adults.
3. A benign lesion.

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.

Hepatic failure 
Etiology. Chronic hepatic disease (e.g., chronic active hepatitis or alcoholic cirrhosis) is the most common cause of hepatic failure although acute liver disease may also be responsible.

- Widespread liver necrosis may be seen with carbon tetrachloride and acetaminophen toxicity. Widespread steatosis is seen in Reye's syndrome, a cause of acute liver failure most often seen in children with a recent history of aspirin ingestion for an unrelated viral illness. 
- Massive necrosis may also be seen in acute viral hepatitis, after certain anesthetic agents, and in shock from any cause. 

Clinical features. Hepatic failure causes jaundice, musty odor of breath and urine, encephalopathy, renal failure (either by simultaneous toxicity to the liver and kidneys or the hepatorerial syndrome), palmar erythema, spider angiomas, gynecomastia , testicular atrophy 

INFLUENZA

An acute viral respiratory infection with influenza, a virus causing fever, coryza, cough, headache, malaise, and inflamed respiratory mucous membranes.

Influenza B viruses typically cause mild respiratory disease

Symptoms and Signs

mild cases:

Chills and fever up to 39 to 39.5° C

Prostration and generalized aches and pains, Headache, photophobia and retrobulbar aching

Respiratory tract symptoms may be mild at first, with scratchy sore throat, substernal burning, nonproductive cough, and sometimes coryza. Later, the lower respiratory illness becomes dominant; cough can be persistent and productive.

severe cases

sputum may be bloody. Skin is warm and flushed. Soft palate, posterior hard palate, tonsillar pillars, and posterior pharyngeal wall may be reddened, but no exudate appears. Eyes water easily, and the conjunctiva may be mildly inflamed

Encephalitis, myocarditis, and myoglobinuria are infrequent complications of influenza and, if present, usually occur during convalescence

Lysosomal (lipid) storage diseases
- Genetic transmission: autosomal recessive.
- This group of diseases is characterized by a deficiency of a particular lysosomal enzyme. This results in an accumulation of the metabolite, which would have otherwise been degraded by the presence of normal levels of this specific enzyme.

Diseases include:
Gaucher’s disease
(1) Deficient enzyme: glucocerebrosidase.
(2) Metabolite that accumulates: glucocerebroside.
(3) Important cells affected: macrophages.

Tay-Sachs disease
(1) Deficient enzyme: hexosaminidase A.
(2) Metabolite that accumulates: GM2 ganglioside.
(3) Important cells affected: neurons.
(4) Symptoms include motor and mental deterioration, blindness, and dementia.
(5) Common in the Ashkenazi Jews.

Niemann-Pick disease
(1) Deficient enzyme: sphingomyelinase.
(2) Metabolite that accumulates: sphingomyelin.
(3) Important cells affected: neurons.

STREPTOCOCCAL INFECTIONS

Most streptococci are normal flora of oropharynx

Group A streptococci:  Str. pyogenes

Group B streptococci:  Str. agalactiae

Str. pneumoniae

Strep viridans group

Group D: Enterococcus (lately Strep. Fecalis and E. fecium), causes urinary tract infections,