**Core Concept**
The management of large antrochoanal polyps in pediatric patients involves addressing the underlying pathophysiology of these nasal masses, which are often benign and arise from the mucous membranes of the maxillary sinus. The treatment goal is to remove the polyp and prevent recurrence while minimizing potential complications.

**Why the Correct Answer is Right**
The current treatment of choice for large antrochoanal polyps in pediatric patients is endoscopic sinus surgery (ESS). This minimally invasive surgical technique allows for precise removal of the polyp, preservation of surrounding nasal structures, and correction of any underlying anatomical abnormalities. ESS is preferred over traditional open surgery due to its lower risk of complications and faster recovery time. The procedure involves the use of a nasal endoscope and specialized instruments to visualize and remove the polyp.

**Why Each Wrong Option is Incorrect**
**Option A:** Medical management with antibiotics and nasal decongestants is inadequate for large antrochoanal polyps, as these treatments only address symptoms and do not address the underlying cause of the polyp.

**Option B:** Polypectomy alone without addressing the underlying sinus anatomy can lead to recurrence of the polyp.

**Option C:** Open sinus surgery is more invasive and carries a higher risk of complications compared to endoscopic sinus surgery.

**Clinical Pearl / High-Yield Fact**
A key consideration in the management of antrochoanal polyps is that they often arise from the maxillary sinus and can extend into the nasal cavity, making endoscopic sinus surgery an ideal treatment option.

**Correct Answer: C. Endoscopic sinus surgery (ESS).**