A 60 year old diabetic patient presents with extermely painful lesion in the external ear and otorrhea not responding to antibiotics. There is evidence of granulation type tissue in the external ear and bony erosion with facial nerve palsy is noted. The most likely diagnosis is-

**Core Concept**
Malignant otitis externa, also known as necrotizing otitis externa, is a severe infection of the external auditory canal, often seen in diabetic patients or immunocompromised individuals. It is characterized by pain, otorrhea, and granulation tissue formation, which can lead to bony erosion and facial nerve palsy.

**Why the Correct Answer is Right**
The correct answer is a type of invasive fungal infection, specifically Mucormycosis, that occurs in diabetic patients with poor glycemic control. It is caused by fungi of the order Mucorales, which can invade blood vessels and cause tissue necrosis. In this case, the presence of granulation tissue and bony erosion with facial nerve palsy suggests a more aggressive and invasive process, consistent with Mucormycosis.

**Why Each Wrong Option is Incorrect**
**Option A:** While diabetic patients are prone to various infections, this option is unlikely because the clinical presentation is more severe than typical bacterial infections.
**Option B:** Otosclerosis is a condition characterized by abnormal bone growth in the middle ear, which can cause hearing loss, but it does not typically present with otorrhea, granulation tissue, or facial nerve palsy.
**Option C:** This option is incorrect because while otitis externa can be severe, it typically does not progress to bony erosion or facial nerve palsy without other underlying factors, such as diabetes or immunocompromise.

**Clinical Pearl / High-Yield Fact**
Malignant otitis externa, particularly Mucormycosis, is a medical emergency that requires prompt recognition and treatment to avoid serious complications, including facial nerve paralysis, meningitis, and death.

**Correct Answer: D. Mucormycosis**

✓ Correct Answer: A. Malignant Otitis Externa