**Core Concept:** Malignant otitis externa (MOE) is a severe form of otomycosis (fungal infection of the external ear canal) that can progress to involve the skull bones and lead to intracranial complications. It is typically caused by Pseudomonas aeruginosa and affects immunocompromised individuals.

**Why the Correct Answer is Right:** Malignant otitis externa is a severe form of otomycosis, so the correct answer should describe a characteristic feature of this condition. Option D states that MOE does not involve the skull, which is false. MOE can indeed cause involvement of the skull bones and intracranial complications due to the aggressive nature of the infection and the compromised immune system of the patient.

**Why Each Wrong Option is Incorrect:**

A. MOE can involve the skull: This statement is incorrect because it is a characteristic feature of malignant otitis externa that the infection extends beyond the ear canal and can involve the skull.

B. MOE is not associated with immunocompromised patients: This statement is incorrect because malignant otitis externa primarily affects immunocompromised patients due to their inability to mount an effective immune response against the infectious agent.

C. MOE is caused by Candida species: MOE is typically caused by Pseudomonas aeruginosa, not Candida species. However, other organisms like Aspergillus, Staphylococcus, and Actinomyces can also cause MOE.

**Clinical Pearl:** Immunocompromised patients must be evaluated and treated promptly for malignant otitis externa, as the infection can progress rapidly, causing serious complications. Early diagnosis and appropriate antimicrobial therapy are essential to prevent complications and improve patient outcomes.