Head and neck sarcomas are rare and consist of a variety of histologic subtypes. We present a case of undifferentiated/unclassified sarcoma (UUS) of the maxillary sinus, a tumor subtype historically known as malignant fibrous histiocytoma (MFH) or undifferentiated pleomorphic sarcoma (UPS). A 50-year-old female patient presented with worsening facial pain and dysphagia. Physical examination demonstrated a large, ulcerated mass protruding from the oral cavity. Computed tomography demonstrated a large, enhancing mass centered in the right maxillary sinus with local invasion. The initial biopsy was read as "central giant cell granuloma." Conservative management yielded no improvement, and the tumor grew steadily. The patient underwent a total maxillectomy with resection of the orbital floor and an anterior ethmoidectomy, followed by radiation and chemotherapy. In addition to treatment of this patient, we discuss a review of the literature and the clinical presentation, radiologic, and histologic findings of this disease.