A 30-year-old man with AIDS complains of severe pain on swallowing. Upper GI endoscopy shows elevated, white plaques on a hyperemic and edematous esophageal mucosa. Which of the following is the most likely diagnosis?
**Core Concept**
Oesophageal candidiasis is a common opportunistic infection in immunocompromised patients, particularly those with AIDS, caused by the overgrowth of Candida albicans. It is characterized by the presence of white plaques on an inflamed and swollen oesophageal mucosa.
**Why the Correct Answer is Right**
The presence of elevated, white plaques on a hyperemic and edematous oesophageal mucosa in a patient with AIDS is highly suggestive of oesophageal candidiasis. Candida albicans adheres to the oesophageal mucosa through mannose receptors and produces enzymes that break down the mucosal barrier, leading to the characteristic white plaques. The inflammation and swelling of the mucosa are a result of the host's immune response to the infection.
**Why Each Wrong Option is Incorrect**
**Option A:** Herpes simplex oesophagitis is another opportunistic infection that can cause severe pain on swallowing in immunocompromised patients. However, it typically presents with multiple, small, ulcerative lesions rather than the white plaques characteristic of oesophageal candidiasis.
**Option B:** Oesophageal varices are a complication of liver cirrhosis and can cause severe pain on swallowing due to bleeding. However, they would not typically present with white plaques on the oesophageal mucosa.
**Option C:** Achalasia is a motility disorder of the oesophagus that can cause difficulty swallowing and regurgitation. However, it would not typically present with white plaques on the oesophageal mucosa.
**Option D:** Oesophageal carcinoma is a type of cancer that can cause pain on swallowing due to obstruction. However, it would not typically present with white plaques on the oesophageal mucosa.
**Clinical Pearl / High-Yield Fact**
Oesophageal candidiasis is a common opportunistic infection in immunocompromised patients and should be suspected in any patient with a weakened immune system and symptoms of oesophageal pain or difficulty swallowing.
**Correct Answer:** C. Oesophageal candidiasis is the most likely diagnosis in this patient.