ATROPHY
It is the acquired decrease in the size of an organ due to decrease in the size and/or number of its constituent cells.
Causes:
(1) Physiological

- Foetal involution.
    o    Branchial clefts.
    o    Ductus arterious.
- Involution of thymus and other lymphoid organs in childhood and adolescence.
- In adults:
    o    Post-partum uterus.
    o    Post-menopausal ovaries and uterus
    o    Post-lactational breast
    o    Thymus.
(2) Pathological:
- Generalised as in

    o    Ageing.
    o    Severe starvation and cachexia
- Localised :
    o    Disuse atropy of bone and muscle.
    o    Ischaemic atrophy as in arteriosclerotic kidney. .
    o    Pressure atrophy due  to tumours and of kidney in hydronephrosis.
    o    Lack of trophic stimulus to endocrines and gonads.
 

EMBOLISM 

An embolus is a detached intravascular solid, liquid, or gaseous mass that is carried by the blood to a site distant from its point of origin

99% due to dislodged thrombus

Types: 
1. Thrombo-embolism 
2. Fat embolism 
3. Air embolism 
4. Nitrogen embolism

 Emboli result in partial or complete vascular occlusion. 

 The consequences of thromboembolism include ischemic necrosis (infarction) of downstream tissue

PULMONARY THROMBOEMBOLISM
- 95% originate from deep veins of L.L

Special variants: - Saddle embolus: at bifurcation of Pulmonary artery

Paradoxical embolus: Passage of an embolus from venous to systemic circulation through IAD, IVD

CLINICAL CONSEQUENCE OF PULMONARY THROMBOEMBOLISM :

Most pulmonary emboli (60% to 80%) are clinically silent because they are small 

a. Organization: 60 – 80 % 
b. Sudden death, Right ventricle failure, CV collapse when more than 60 % of pulmonary vessels are obstructed. 
c. Pulmonary hemorrhage: obstruction of medium sized arteries. 
d. Pulmonary Hypertension and right ventricular failure due to multiple emboli over a long time.

Systemic thromboembolism

Emboli traveling within the arterial circulation 
80% due to intracardiac mural thrombi
2/3  Lt. ventricular failure

 The major targets are: 
 
 1. Lower limbs 75% 
 2. Brain 10% 
 3. Intestines 
 4. Kidneys 
 5. Spleen

Fat embolism 

Causes 
1. Skeletal injury (fractures of long bones ) 
2. Adipose tissue Injury

Mechanical obstruction is exacerbated by free fatty acid release from the fat globules, causing local toxic injury to endothelium. - In skeletal injury, fat embolism occurs in 90% of cases, but only 10% or less have clinical findings

 Fat embolism syndrome is characterized by 
 
 A. Pulmonary Insufficiency 
 B. Neurologic symptoms 
 C. Anemia 
 D. Thrombocytopenia 
 E. Death in 10% of the case 
 
 Symptoms appears 1-3 days after injury
 
 Tachypnea, Dyspnea, Tachycardia and Neurological symptoms
 
Air Embolism 

causes: 1. Obstetric procedures 
2. Chest wall injury 
3. Decompression sickness: in Scuba and deep-sea divers ((nitrogen )) 

 More then 100ml of air is required to produce clinical effect. 
 
 Clinical consequence
 1. Painful joints: due to rapid formation of gas bubbles within Sk. Muscles and supporting tissues. 
 2. Focal ischemia in brain and heart 
 3. Lung edema, Hemorrhage, atelectasis, emphysema, which all lead to Respiratory distress. (chokes) 
 4. caisson disease: gas emboli in the bones leads to multiple foci of ischemic necrosis, usually the heads of the femurs, tibias, and humeri
 
 Amniotic fluid embolism 
 - Mortality Rate = 20%-40% 
 - Very rare complication of labor 
 
 - due to infusion of amniotic fluid into maternal circulation via tears in placental membranes and rupture of uterine veins. 
 - sudden severe dyspnea, cyanosis, and hypotensive shock, followed by seizures, DIC and coma 
 
 - Findings: Squamous cells, languo hair, fat, mucin …..etc within the pulmonary microcirculation

Cytopathologic techniques

Cytopathology is the study of cells from various body sites to determine the cause or nature of disease.

Applications of cytopathology:

1. Screening for the early detection of asymptomatic cancer

2. Diagnosis of symptomatic cancer

3. Surveillance of patients treated for cancer

Cytopathologic methods

There are different cytopathologic methods including:

1. Fine-needle aspiration cytology (FNAC) -In FNAC, cells are obtained by aspirating the diseased organ using a very thin needle under negative pressure.

Superficial organs (e.g. thyroid, breast, lymph nodes, skin and soft tissues) can be easily aspirated.

Deep organs, such as the lung, mediastinum, liver, pancreas, kidney, adrenal gland, and retroperitoneum are aspirated with guidance by fluoroscopy, ultrasound or CT scan.

1. Exfoliative cytology

Refers to the examination of cells that are shed spontaneously into body fluids or secretions. Examples include sputum, cerebrospinal fluid, urine, effusions in body cavities (pleura, pericardium, peritoneum), nipple discharge and vaginal discharge.

1. Abrasive cytology

Refers to methods by which cells are dislodged by various tools from body surfaces (skin, mucous membranes, and serous membranes). E.g. preparation of cervical smears with a spatula or a small brush to detect cancer of the uterine cervix at early stages.

Multiple myeloma.

Blood picture:

- Marked rouleaux formation.
- Normpcytic normochromic anaemia.
- There may be leucopenia or leucoery!hrohlastic reaction.
- Atypical plasma cells may be seen in some patients
- Raised ESR
- Monoclonal hypergammaglobulinaemia 
- If light chains are produced in excess, they are excreted in urine as bence jones protein

Bone marrow

- Hyper cellular
- Plasma cells from at least 15 – 30% atypical forms and myeloma cells are seen.
 

Other lung diseases

1.Sarcoidosis

1. Sarcoidosis

a. More common in African-Americans.

b. Associated with the presence of noncaseating granulomas.

Sarcoidosis is an immune system disorder characterised by non-necrotising granulomas (small inflammatory nodules). Virtually any organ can be affected, however, granulomas most often appear in the lungs or the lymph nodes.

Signs and symptoms

• Sarcoidosis is a systemic disease that can affect any organ. Common symptoms are vague, such as fatigue unchanged by sleep, lack of energy, aches and pains, dry eyes, blurry vision, shortness of breath, a dry hacking cough or skin lesions. The cutaneous symptoms are protean, and range from rashes and noduli (small bumps) to erythema nodosum or lupus pernio
• Renal, liver, heart or brain involvement may cause further symptoms and altered functioning. Manifestations in the eye include uveitis and retinal inflammation
• Sarcoidosis affecting the brain or nerves is known as neurosarcoidosis.
• Hypercalcemia (high calcium levels) and its symptoms may be the result of excessive vitamin D production
• Sarcoidosis most often manifests as a restrictive disease of the lungs, causing a decrease in lung volume and decreased compliance (the ability to stretch). The vital capacity (full breath in, to full breath out) is decreased, and most of this air can be blown out in the first second. This means the FEV1/FVC ratio is increased from the normal of about 80%, to 90%.

Treatment

Corticosteroids, most commonly prednisone

2. Cystic fibrosis

a. Transmission: caused by a genetic mutation (nucleotide deletion) on chromosome 7, resulting in abnormal chloride channels.

b. The most common hereditary disease in Caucasians.

c. Genetic transmission: autosomal recessive.

d. Affects all exocrine glands. Organs affected include lungs, pancreas, salivary glands, and intestines. Thick secretions or mucous plugs are

seen to obstruct the pulmonary airways and intestinal tracts.

e. Is ultimately fatal.

f. Diagnostic test: sweat test—sweat contains increased amounts of chloride.

3. Atelectasis

a. Characterized by collapse of the alveoli.

b. May be caused by a deficiency of surfactant and/or hypoventilation of alveoli.

Metastatic Tumors 

These are the most common malignant tumor of bone. Certain tumors exhibit a distinct skeletal prediliction. In adults more than 75% of skeletal metastases originate from cancers of the prostate, breast, kidney, and lung. In children, neuroblastoma, Wilms' tumor, osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma are the common sources of bony metastases. Most metastases involve the axial skeleton (vertebral column, pelvis, ribs, skull, sternum), proximal femur, and humerus. The radiologic appearance of metastases can be purely osteolytic, purely osteoblastic, or mixed osteolytic-osteoblastic (majority of cases). In lytic lesions (e.g., kidney& lung), the metastatic cells secrete substances such as prostaglandins, interleukins, etc. that stimulate osteoclastic bone resorption; the tumor cells themselves do not directly resorb bone. Similarly, metastases that elicit a blastic response (e.g., prostate adenocarcinoma) do so by stimulating osteoblastic bone formation.