A Report on Synchronous Polymorphous Low-grade Adenocarcinoma and Unknown Primary Squamous Cell Carcinoma

ABSTRACT Background This is a case report of synchronous, noncollision head and neck malignancies, consisting of a large polymorphous low-grade adenocarcinoma (PLGA) and an unknown primary squamous cell carcinoma (SCC) that was diagnosed on final pathology. Materials and methods Positron emission tomography– computed tomography (CT) scan with and without contrast was obtained, which showed a large destructive soft tissue mass emanating from the right maxilla into the right maxillary sinus with invasion into the surrounding tissue and bone, compatible with an underlying primary maxillary malignancy. Increased D-18 fluorodeoxyglucose activity was also seen in the neck corresponding to numerous bilateral cervical lymph nodes. Magnetic resonance imaging showed the extent of the soft tissue mass, which expanded to the inferior aspect of the right orbital floor, with no evidence of gross invasion into the orbit. Results The patient underwent a subtotal maxillectomy, bilateral modified radial neck dissection, and reconstruction. Pathology revealed metastatic PLGA present in the right cervical lymph nodes. Left cervical lymph nodes, however, revealed metastatic SSC. The patient was taken back to the operating room and a panendoscopy was performed. Physical examination was benign and multiple biopsies were negative for SSC. The patient underwent radiation therapy for PLGA and unknown primary SSC antigen. Conclusion Synchronous tumors of the head and neck are seldom reported and they present unique treatment challenges. This case report discusses the diagnosis, management, and unique nature of two malignant synchronous noncollision tumors in the head and neck. How to cite this article Fisher AD, McClure SA, Franco J. A Report on Synchronous Polymorphous Low-grade Adenocarcinoma and Unknown Primary Squamous Cell Carcinoma. Int J Head Neck Surg 2015;6(4):181-186.