Abstract
Introduction/Objective
Myoepithelial carcinoma is identified by nearly exclusive myoepithelial differentiation and evidence of malignancy. It may arise de novo or in preexisting benign tumors including pleomorphic adenoma and benign myoepithelioma. It occurs most commonly in the parotid gland followed by submandibular glands, minor salivary glands, and occasionally in the sublingual gland. Nasopharyngeal origin has been rarely reported.
Methods/Case Report
An afebrile 19-year-old female presented to the emergency department with persistent facial pressure, otalgia (right side greater than left side), rhinorrhea, and several episodes of epistaxis. One month before, she has been treated with Amoxicillin for three days with no relief, where Augmentin started for her for five days. About four days prior presentation, she was placed on Prednisone and Cefdinir. Over the next several days, she began having throat pain with difficulty swallowing. Routine blood work revealed a leukocytosis of 14.2 with normal differentiation. CT of the neck showed a large soft tissue mass centered at the right nasopharynx. Flexible nasal endoscopy performed bilaterally to reveal the nasopharynx is entirely obstructed with a lobulated mass filling the nasopharynx. On the right side, it extends into the posterior nasal passage filling the sphenoethmoid recess and the posterior floor of the nasal passage. Outpatient biopsy from nasopharynx mass is also performed.
Results (if a Case Study enter NA)
Mass biopsy reveals a mucinous and chondromyxoid background with mixed epithelial and myoepithelial differentiation. The is squamous metaplasia of myoepithelial cells and prominent mitotic activity and apoptotic activity. Immunohistochemistry was positive for CK5/6, calponin, BCL2, SMA, BerEp4, Sox10, and a proliferative index up to 40%. Based on this information Myoepithelial Carcinoma ex-pleomorphic adenoma of the nasopharynx is the diagnosis.
Conclusion
Carcinoma ex pleomorphic adenoma is usually a high-grade malignancy. It occurs most commonly in the parotid gland, followed by submandibular glands, minor salivary glands, and occasionally in the sublingual gland. Our case is one of the few cases of myoepithelial carcinoma arising in nasopharyngeal pleomorphic adenoma.
A De Novo Malignant Mixed Tumor (Carcinosarcoma) of the Parotid Gland: Case Report