**Core Concept**
The patient has a history of corrosive poisoning leading to a complex stricture in the mid esophagus, which was attempted to be dilated. This procedure can cause a serious complication known as esophageal perforation, where the esophageal wall is breached, leading to leakage of air, food, and saliva into the surrounding tissues.

**Why the Correct Answer is Right**
Esophageal perforation can lead to mediastinitis, an infection of the mediastinum, which is the central part of the chest cavity. The presence of mediastinitis can cause surgical emphysema, which is the accumulation of air in the tissues of the neck and chest. In a chest X-ray, surgical emphysema would appear as air-filled spaces or bubbles in the soft tissues of the neck and chest. This is a life-threatening complication that requires immediate medical attention.

**Why Each Wrong Option is Incorrect**
**Option A:** A normal chest X-ray would not be expected in a patient with surgical emphysema and a history of esophageal perforation.

**Option B:** A pleural effusion, which is the accumulation of fluid in the pleural space, may be seen in some cases of esophageal perforation, but it is not the most expected finding in this scenario.

**Option C:** A pneumothorax, which is the accumulation of air in the pleural space, can occur in esophageal perforation, but it is not the most likely finding in this case.

**Option D:** A normal chest X-ray is not expected, as the patient has a history of esophageal perforation and surgical emphysema.

**Clinical Pearl / High-Yield Fact**
Esophageal perforation is a medical emergency that requires prompt recognition and treatment. The classic triad of symptoms is chest pain, dysphagia, and subcutaneous emphysema. In a patient with a history of corrosive poisoning and severe dysphagia, esophageal perforation should be suspected and investigated promptly.

**Correct Answer:** D. A chest X-ray would show surgical emphysema, which is the accumulation of air in the tissues of the neck and chest.