**Question:** True statement about malignant otitis externa is -

A. Malignant otitis externa is a life-threatening infection affecting the temporal bone.
B. It is caused by bacteria like Pseudomonas aeruginosa.
C. The infection is limited to the external auditory canal only.
D. The condition is rare and occurs in immunocompetent individuals.

**Correct Answer:**

**Core Concept:** Malignant otitis externa is a severe, progressive, and life-threatening infection affecting the temporal bone. It is typically caused by Pseudomonas aeruginosa and other opportunistic pathogens, which can lead to destruction of bone, meningitis, and intracranial extension.

**Why the Correct Answer is Right:**

Malignant otitis externa is a severe infection affecting the temporal bone, which is the correct description for the condition. It is characterized by destructive bone lesions and the involvement of the surrounding tissues, including the skull base and intracranial structures. The infection is usually caused by opportunistic pathogens, such as Pseudomonas aeruginosa, which can lead to severe complications if left untreated.

**Why Each Wrong Option is Incorrect:**

A. This option is incorrect because malignant otitis externa predominantly affects the external auditory canal, not the temporal bone. Although the infection can spread to the temporal bone, the infection is initially located in the external auditory canal.

B. While Pseudomonas aeruginosa is one of the causative organisms in malignant otitis externa, this option is incorrect because the infection can also be caused by other pathogens like Aspergillus, Staphylococcus aureus, or Candida species. The statement "only caused by bacteria" is too restrictive and does not encompass all potential pathogens.

C. This option is incorrect because malignant otitis externa does not only affect the external auditory canal but also involves the surrounding tissues, including the temporal bone. The infection spreads from the external auditory canal to the temporal bone due to the proximity and the lack of robust immune defenses in the temporal bone.

D. This option is incorrect because malignant otitis externa is not rare and can occur in immunocompetent individuals. Although the condition is more common in immunocompromised patients, it can still affect immunocompetent individuals as well.

**Clinical Pearls:**

1. Malignant otitis externa is a serious infection that requires prompt diagnosis and treatment to prevent complications and potential life-threatening consequences.
2. In immunocompromised patients, the infection might be more severe and spread more rapidly, but it can still occur in immunocompetent individuals as well.
3. Early recognition and treatment of the condition are crucial to prevent complications like meningitis, brain abscess, and osteomyelitis.
4. Pseudomonas aeruginosa is a common causative organism, but other pathogens like Aspergillus, Staphylococcus aureus, or Candida species can also cause malignant otitis externa.