Pleomorphic adenoma with pulmonary metastases

Introduction:

With about 70% the pleomorphic adenoma (PA) is by far the most common benign salivary gland tumor and in about 80% located in the parotid gland. Women between 30 and 40 years are most frequently affected. The PA is a benign tumor which can develop malignant characteristics in 2 – 4% of cases.

Methods:

Case report, literature research

Results:

A year after removing a PA by partial parotidectomy in a 77-year-old female patient, she presented again with a parotideal rapidly progressing mass. After re-parotidectomy the histology revealed a PA once again with no evidence of malignancy. A thorax CT showed multiple bipulmonary metastases which histologically matched metastases of the PA.

The discrepancy between the histology showing a pleomorphic adenoma with increased mitotic activity (ki67 of 25%) and the clinically progressing bipulmonary metastases led to the assessment that these findings were malignant. A systemic therapy was initiated. Due to multiple local recurrences after systemic therapy the patient was included in a study with Entrectinib.

Conclusion:

Metastatic pleomorphic adenoma (MPA) is rare and histologically indistinguishable from PA. Despite the benign histological appearance, the MPA shows a malignant behavior and is associated with multiple local recurrences.

Publication History

Publication Date:
23 April 2019 (online)