Myoepithelial carcinoma ex parotid pleomorphic adenoma: a case report

A 35-year-old woman had a mass in the right parotid ten years ago. Complete resection of right parotid was performed. Histological diagnosis was “parotid pleomorphic adenoma”. There were no neurological deficits postoperatively. Subsequently, radiotherapy was administrated on tumor bed region with a total dose of 50 Gy at 2 Gy/d/fraction. Eight years after surgery, she had cough, sputum and right side chest back pain. Chest CT revealed the patient’s lungs had multiple mass metastases (Figure 1A). Multiple metastases to the scalp were also detected with MRI (Figure 1B,C). The initial diagnosis was modified to be “parotid pleomorphic adenoma consisted of myoepithelial carcinoma” according to an open biopsy. Generally, parotid pleomorphic adenoma is a slow-growing benign neoplasm, which most commonly presents as a solitary lesion (1). If the treatment failed, most patient shows local recurrence (2). Despite myoepithelial carcinoma is a rare salivary gland tumor (3), it shows high-grade malignancy mostly arising from pleomorphic adenoma in the parotid (4) or other locations (5). Herein we reported this rare case of myoepithelial carcinoma ex parotid pleomorphic adenoma with high aggressiveness eight years after parotidectomy. It suggests attentions should be paid to parotid pleomorphic adenoma with malignant degeneration to myoepithelial carcinoma even for a long-term interim period after surgery and radiotherapy. Now this patient is scheduled for chemotherapy.

Figure 1 Chest CT scan shows multiple mass metastases (arrowheads) in both lungs (A); Head MRI exhibits multiple metastases (arrowheads) to the scalp (B, C)

Acknowledgements

Disclosure: The authors declare no conflict of interest.

References

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