HYPERTROPHY
Increase in the size of an organ or tissue due to increase in the size of its Constituent cells.

1. Skeletal muscle due to -exercise.

2. Cardiac muscle of:
- Left ventricle in:
    o    Hypertension.
    o    Aortic valvular lesion.
    o    Severe anaemia.
- Right ventricle in :
    o    Mitral stenosis
    o    Cor pulmonale
    
3. Smooth muscle of:

- GIT proximal to strictures.
- Uterus in pregnancy.
 

Peutz-Jeghers syndrome
1. Lesions appear as small, melanotic, and freckle-like. They can be found on the skin, oral mucosa, lips, feet, and hands. 
2. May also present with intestinal polyps, which may develop into a gastrointestinal carcinoma. 
3. Genetic transmission: autosomal dominant.

Fungal
 
Superficial mycoses

1. Superficial mycoses→outermost layers of the skin or its appendages; skin, nails and/or hair.
2. Dermatophytoses transmitted by contact with man (anthropophilic; weak inflammatory response), animals (zoophilic; brisk inflammatory response), or contact with soil (geophilic; strongest inflammatory response).
3. Trichophyton→hair, skin, or nails; Microsporum → hair and skin; and Epidermophyton→skin alone.
4. The diagnosis is best made by culture of skin scrapings secured from the leading edge of the lesion.
 - use Wood's light to check for fluorescing metabolites.
 - direct KOH preparations of the scraped material
 
 Subcutaneous Mycoses
 
1. Subcutaneous mycoses are usually related to traumatic implantation into the skin.
2. Chromoblastomycosis, or verrucous (wart-like) dermatitis, is a chronic skin lesion associated with several pigmented fungi (Fonsecaea, Phialophora, and Cladosporium).
 - granulomatous reaction in subcutaneous tissue are pigmented, thick walled bodies are visible in tissue section.
3. Mycetomas (maduromycosis) are characterized by a localized, tumorous nodule (usually foot) that occurs in response to chronic progressive destruction of skin, subcutaneous tissue, fascia, muscle and bone 

4. Sporotrichosis is caused by the dimorphous fungus, Sporothrix schenckii.
 - traumatic implantation of the fungus growing in soil, thus the association with "rose gardeners disease".
 - MC lymphocutaneous disease → painless nodule at inoculation site → chain of suppurating subcutaneous nodules that drain to the skin surface along the course of the lymphatics.

- cigar shaped yeast forms are seen in the suppurative nodules and asteroid bodies (Splendore-Hoeppi phenomenon) are noted within granulomatous microabscesses.
 - treatment: oral potassium iodide

Pneumoconioses—are environmentally related lung diseases that result from chronic inhalation of various substances.

1. Silicosis (stone mason’s disease) 
a. Inhalant: silica dust.
b. Associated with extensive fibrosis of the lungs.
c. Patients have a higher susceptibility to tuberculosis infections.

2. Asbestosis
a. Inhalant: asbestos fibers.
b. Associated with the presence of pleural plaques.
c. Consequences include:
(1) Mesothelioma (malignant mesothelial tumor).
(2) Bronchogenic carcinoma.

3. Anthracosis
a. Inhalant: carbon dust.
b. Usually not as harmful as silicosis or asbestosis.
c. Associated with the presence of macrophages containing carbon.

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.

 IMMUNO PATHOLOGY

Abnormalities of immune reactions are of 3 main groups

• Hypersensitivity,
• Immuno deficiency,
• Auto immunity.

Hypersensitivity (ALLERGY)

This is an exaggerated or altered immune response resulting in adverse effects

They are classified into 4 main types.

I. Type I-(reaginic, anaphylactic). This is mediated by cytophylic Ig E antibodies, which get bound to mast cells. On re-exposure, the Ag-Ab reaction occurs on the mast cell surface releasing histamine.

Clinical  situations

I. Systemic anaphylaxis, presenting with bronchospasm oedema hypertension, and even death.

2. Local (atopic) allergy.

• Allergic rhinitis (hay fever)
• Asthma
• Urticaria.
• Food allergies.

2. Type II. (cytotoxic). Antibody combines with antigen present on-cell surface. The antigen may be naturally present on the surface or an extrinsic substance (e.g.drug) attached to cell surface.

The cell is then destroyed by complement mediated lysis (C89) or phagocytosis of the antibody coated cell.

Clinical situations

• Haemolytic anemia.
• Transfusion reaction
• Auto immune haemolytic anemia.
• Haemolysis due to some drugs like Alpha methyl dopa

Drug induced thrombocytopenia (especially sedormid).

Agranulocytosis due to sensitivity to some drugs.

Goodpasture’s syndrome-glomermerulonephritis due to anti basement membrane antibodies.

3. Type III. (Immune complex disease). Circulating immune complexes especially

small soluble complexes tend to deposit in tissues especially kidney, joints, heart and

arteries.

These then cause clumping of platelets with subsequent release of histamine. and

serotonin resulting in increased permeability. Also, complement activation occurs which

being chemotactic results in aggregation of polymorphs and necrotising vasculitis due to

release of lysosmal enzymes

Clinical situations

• Serum sickness.
• Immune complex glomerulonephritis.
• Systemic lupus erythematosus.
• Allergic alveolitis.
• Immune based vasculitis like
  • Drug induced vasculitis.
  • Henoch – Schonlein purpura

4. Type IV. (Cell mediated). The sensitized lymphocytes may cause damage by

cytotoxicity or by lymphokines and secondarily involving macrophages in the reaction.

Clinical situations

I. Caseation necrosis in tuberculosis.

2. Contact dermatitis to

• Metals.
• Rubber.
• Drugs (topical).
• Dinitrochlorbenzene (DNCB).

5. Type V. (stimulatory) This is classed by some workers separately and by other with

cytotoxic type (Type II) with a stimulatory instead of toxic effect

Clinical Situations :

LATS (long acting thyroid stimulator) results in thyrotoxicosis (Grave’s disease)