**Core Concept**
Cystic glandular hyperplasia, a type of endometrial hyperplasia, is a benign condition characterized by excessive proliferation of the glandular epithelium in the endometrium. This condition can potentially progress to endometrial carcinoma, a malignant transformation that poses significant clinical concerns.

**Why the Correct Answer is Right**
The correct answer, 1%, represents the approximate percentage change of cystic glandular hyperplasia turning to malignancy. This is based on the understanding that the risk of malignant transformation in cystic glandular hyperplasia is generally low, ranging around 1%. This is because cystic glandular hyperplasia is considered a less aggressive form of endometrial hyperplasia, with a lower potential for malignant progression compared to other types, such as atypical endometrial hyperplasia. The exact pathogenesis of this transformation involves complex interactions between hormonal influences, genetic mutations, and molecular pathways, including the PI3K/AKT pathway, which regulates cell proliferation and survival.

**Why Each Wrong Option is Incorrect**
**Option A:** 0.10% is too low, as it underestimates the risk of malignant transformation in cystic glandular hyperplasia.
**Option B:** 2% is higher than the accepted risk, which is generally considered to be around 1%.
**Option D:** 10% is significantly higher than the actual risk, suggesting a higher potential for malignant transformation than is clinically recognized.

**Clinical Pearl / High-Yield Fact**
It is essential for clinicians to accurately diagnose and manage endometrial hyperplasia, as the risk of malignant transformation varies depending on the type and severity of the condition. A thorough understanding of the pathogenesis and clinical characteristics of cystic glandular hyperplasia is crucial for providing appropriate patient care and counseling.

**✓ Correct Answer: C. 1%**