Mullerian adenosarcomas: an immunophenotypic analysis of 35 cases

Area of Science:

• Gynecologic Pathology
• Surgical Pathology
• Oncology

Background:

• Mullerian adenosarcomas (MAs) are rare neoplasms with benign epithelial and malignant mesenchymal components.
• The mesenchymal component dictates the clinical behavior and differential diagnosis of MAs.
• Understanding the immunophenotypic profile is crucial for accurate diagnosis and prognosis.

Purpose of the Study:

• To determine the immunophenotypic profile of the epithelial and mesenchymal components of MAs.
• To identify differences between conventional mesenchymal areas and sarcomatous overgrowth.
• To correlate immunophenotypic findings with tumor behavior.

Main Methods:

• Immunohistochemical analysis of 35 MAs (28 without sarcomatous overgrowth, 7 with sarcomatous overgrowth).
• Staining for ER, PR, AR, CD10, WT1, muscle markers, cytokeratin, CD34, calretinin, inhibin, c-kit, and Ki-67.
• Comparison of marker expression between conventional and sarcomatous areas.

Main Results:

• Mesenchymal components typically expressed ER, PR, WT1, and CD10, similar to endometrial stromal tumors.
• Sarcomatous overgrowth areas showed reduced expression of ER, PR, and CD10 compared to conventional areas.
• Ki-67 proliferation index was significantly higher in sarcomatous overgrowth areas (median 28%) than in conventional areas (median 5%).
• Epithelial components expressed ER, PR, and cytokeratin.

Conclusions:

• The immunophenotype of most MAs resembles endometrial stromal tumors.
• Loss of ER, PR, and CD10 expression in sarcomatous overgrowth areas suggests dedifferentiation.
• Increased proliferation in sarcomatous areas correlates with aggressive behavior.