The stromal component of large endometrial polyps

Area of Science:

• Gynecologic Pathology
• Surgical Pathology
• Reproductive Medicine

Background:

• Benign endometrial polyps are common, but their stromal characteristics can overlap with malignant tumors like adenofibroma and adenosarcoma.
• Limited data exists on stromal mitotic activity, cellularity, and atypia in benign endometrial polyps, complicating differential diagnosis.
• Accurate differentiation is crucial for appropriate patient management and avoiding unnecessary interventions.

Purpose of the Study:

• To analyze the range of stromal mitotic activity, cellularity, and atypia in benign endometrial polyps.
• To establish criteria for differentiating benign polyps from adenofibroma and adenosarcoma based on stromal features.
• To provide guidance for pathologists encountering these features in endometrial polyps.

Main Methods:

• Histopathological analysis of stromal features in 66 benign endometrial polyps (≥1 cm) from 56 patients.
• Evaluation of stromal mitotic figures (MFs/10 HPFs), cellularity, and nuclear atypia.
• Correlation of findings with clinical follow-up data.

Main Results:

• 76% of polyps exhibited predominantly endometrial or mixed stromal components.
• Stromal mitoses were common in these polyps, averaging 1.2 MFs/10 HPFs (range 0-5.8).
• Mild stromal cellularity and atypia were frequent; 24% had ≥2 MFs/10 HPFs, a rate seen in some adenosarcomas, but without other malignant features. Follow-up was uneventful.

Conclusions:

• Benign endometrial polyps with endometrial-type stroma frequently display mitotic activity.
• Significant stromal mitotic activity alone is not indicative of malignancy in the absence of other features.
• These findings aid in distinguishing benign polyps from potentially malignant lesions, improving diagnostic accuracy.