Anatomy and Histology of the Normal Lung and Airways

Examination of pulmonary and pleural biopsies

Useful chromatic and immunostains in pulmonary pathology

Percutaneous Needle and Trucut Biopsy Specimen

Bronchial Biopsy Specimen

Transbronchial Biopsy Specimen

Transbronchial biopsy in lung transplant recipients

Open lung biopsy

Lobectomy and pneumonectomy specimen

Histopathological reporting of pulmonary parenchymal biopsies

Histopathological reporting of pulmonary biopsies in cases of Idiopathic Pulmonary Fibrosis

Closed pleural biopsy for neoplasm or inflammatory lesions ; Open pleural biopsy and pneumonectomy or pleural stripping

Anatomical Distribution of Pulmonary Disease

Congenital Cystic Adenomatoid  Malformation

Bronchopulmonary Sequestration

Acute Respiratory Distress Syndrome

Neonatal Respiratory Distress Syndrome

Chronic Obstructive Pulmonary Disease

Visit: Inflammation ; Inflammatory cells in acute and chronic inflammation ; Acute Inflammation ; Chemical Mediators ;Chronic Inflammation ; Wound Healing .

Types of acute inflammation:

1. Catarrhal type- Mild inflammation in mucous membrane and is characterized by copious outpouring of mucus along with desquamated epithelial cells and a few leucocytes. Example: Common cold, catarrhal appendicitis etc.

2. Serous type- Mild inflammation in serous surface such as pleural cavity joint cavity etc with accumulation of low protein containing fluid (effusion). Example: Tuberculous pleurisy. It is also seen due to repeated mild trauma. Example: Common blisters.

3. Fibrinous type- Characterized by outpouring of exudates with high protein and less volume. Commonly seen in serous surface such as pleura, peritoneum, pericardium. Two  contiguous surfaces covered in fibrin tend to stick together and  if not lysed scar tissue is formed with permanent loss of function - Example:  Adhesive and constrictive pericarditis. Lobar Pneumonia due to Streptococcus pneumoniae is associated  with massive fibrinous exudates in the lung alveoli. Visit: Pericardial Disease

Lobar pneumonia shows massive fibrinous inflammatory exudates in alveoli.

4. Membranous type- Fibrinous inflammation in which network of fibrin entangling inflammatory cells and bacteria forms pseudo-membrane. Example: Diphtheria , Bacillary dysentery.  

Pseudomembranous inflammation in diphtheria showing network of fibrin entangling inflammatory cells. Bacteria forming pseudo-membrane (left).

5. Suppurative or purulent type-  Usually caused by  pyogenic bacteria and is characterized by pus formation Example: Abscess.

                                      Abscess:  

Abscess is the localized collection of pus, commonly seen solid block of tissue - Example: dermis, liver, kidney, brain etc. Pus consists of partly or completely liquified dead tissue mixed with dead or dying neutrophils and living or dead bacteria,

Pyemic abscess in myocardium. Abscess containing necrotic cell debris, colonies of bacteria, and large number of neutrophils, many of them degenerate.Myocardium is on the right.    

Microscopic feature:

Central purulent zone is surrounded from inside outwards by, pus cells, living neutrophils and granulation tissue known as  pyogenic membrane. This last layer represents the repair process and serves as a barrier to the spread of inflammation. It also prevents the discharge of pus from the abscess without which healing cannot occur. When pus is drained the granulation tissue proliferates to replace the necrotic tissues and repair is done.

6. Phlegmonous type- (Phlegmon means fire): Characterized by woody hardness of the inflamed area due to low resistance  of the body and high virulence of the bacteria - Example: Erysipelas, pelvic cellulites etc.

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