**Core Concept**
Antrochoanal polyps are benign, non-neoplastic growths that arise from the mucous membranes of the maxillary sinus and extend into the nasal cavity, specifically into the choana. This process involves the proliferation of mucous gland cells and fibrous tissue.

**Why the Correct Answer is Right**
The growth of antrochoanal polyps is associated with the proliferation of mucous gland cells and fibrous tissue. The polyps are usually caused by an abnormality in the drainage of the maxillary sinus, leading to chronic inflammation and mucous gland hypertrophy. The polyps are known to be connected to the maxillary sinus by a narrow stalk, which is a characteristic feature of this condition.

**Why Each Wrong Option is Incorrect**
**Option A:** Antrochoanal polyps are not typically associated with a malignant transformation. They are benign growths that do not have the potential to become cancerous.

**Option B:** The polyps are not usually caused by an allergic reaction. While allergies can cause nasal polyps, antrochoanal polyps have a distinct etiology.

**Option C:** The growth of antrochoanal polyps is not typically associated with a significant increase in the size of the maxillary sinus. The polyps can cause nasal obstruction and other symptoms, but the size of the sinus itself is not typically affected.

**Clinical Pearl / High-Yield Fact**
Antrochoanal polyps are usually solitary and can cause significant nasal obstruction, which is a key clinical feature. They are also often associated with a characteristic "nasal mass" on physical examination.

**Correct Answer:** None given, please provide options (A, B, C, D) for the question.