Question

Which condition does NOT feature granulomas?

• A. Mycoplasma pneumoniae
• B. Mycobacterium tuberculosis
• C. Mycobacterium leprae
• D. Yersinia enterocolitica

Hint:

TB, leprosy and Yersinia all form granulomas; Mycoplasma pneumoniae causes interstitial pneumonia without granuloma formation.

Answer 1

The Correct Option is A

Step 1: Set the rule for a granuloma.
Whenever macrophages cannot digest and clear an antigen, they wall it off by clumping together into epithelioid cells, sometimes fusing into giant cells. This walling off is the granuloma.

Step 2: Check the three infections that do wall things off.
Tuberculosis is the classic granuloma former, with central caseous necrosis. Tuberculoid leprosy also produces sharp, well formed granulomas because the immune response there is strong. Yersinia enterocolitica infection in the gut can produce granulomatous ileitis and lymphadenitis, closely mimicking Crohn disease.

Step 3: Check Mycoplasma pneumoniae.
This bacterium lacks a cell wall and causes a milder, diffuse interstitial lung inflammation. The reaction is lymphocytic and plasma cell rich, spread through the septa, not a focal macrophage wall. So no granulomas form here.

Step 4: Conclude.
\[ \boxed{\text{Mycoplasma pneumoniae}} \]