Pneumonia: Pathology review

Two people came to your clinic one day.

Mariah is a 54-year-old smoker, who came in with with productive cough with yellow sputum and left-sided chest pain.

Physical examination reveals fever, tachycardia, and tachypnea. Her lung sounds are barely audible, but it had crackles at the left base.

Next is Jeremy, a 64-year-old man who was hospitalized for a stroke 2 weeks ago.

He recently developed a cough and right-sided chest pain.

He is tachycardic and has a fever of 38.4°C.

Examination reveals fremitus, decreased breath sounds, and dullness to percussion in the right lower lung field.

Chest x-rays were performed which showed a left lower lobe infiltrate in Mariah’s case, and a right lower lobe infiltrate in Jeremy’s.

Now, both people have pneumonia.

So pneumonia is an infection of the lung tissue.

Some microbes can overcome the innate defenses of the lungs and immune system to colonize the bronchioles or alveoli.

These pathogens then triggers an inflammatory response.

Inflammatory cells, such as white blood cells, dead bacteria, proteins and fluid from the damaged tissue, form a fluid called exudate which can be coughed up and expelled from the body.

However they can also accumulate in the lungs, filling up the alveoli.

We can divide pneumonia into “classic” pneumonia or “atypical pneumonia based on symptoms.

So with classical pneumonia, high yield symptoms might include dyspnea, or shortness of breath, fatigue, and fever.

Individuals might also develop pleuritic chest pain, which is characterized by sudden and intense sharp, stabbing, or burning pain in the chest when inhaling and exhaling; and productive cough with yellow sputum.

Besides these, High yield signs that might come up on your exam include dullness to percussion, which suggests that there’s a lung consolidation.

This occurs because the air in the alveoli is replaced by pus and fluid so the sound will lose its normal tympanic or drum-like quality.