Secondary undifferentiated pleomorphic sarcoma of the mandible in a HIV patient who underwent radiotherapy for oral carcinoma

Undifferentiated pleomorphic sarcoma (UPS), also defined malignant fibrous histiocytoma (MFH), is one of the most common sarcomas affecting soft tissues in adults, but it can also arise as a primary tumor in bone. UPS is extremely uncommon in the lower jaw and presents very aggressive clinical behavior with high rate of local recurrences and frequent metastases. Secondary UPS are even rarer than primary forms, and they are usually closely associated with local trauma or radiotherapy. This case report aims at illustrating a rare case of secondary UPS of the mandible in an 81-year-old male affected by HIV, maxillary oral squamous cell carcinoma (and mandibular recurrence), and who underwent head and neck radiotherapy. The complete immunohistochemical pattern of the lesion is reported. Due to his medical history and systemic status, the patient has been considered not eligible for further surgical procedures nor radiotherapy. Therefore, a palliative care treatment has been scheduled.