Primary peripheral primitive neuroectodermal tumor of the mandible
A 22-year-old female presented with a complaint of insidious onset painless swelling in the left side of the face which had increased in size over 4 months. Clinical examination revealed a firm, well-circumscribed swelling measuring 7 × 7 cm in the left parotid region with numbness in the chin region []. The angle of the mandible was widened by the tumor resulting in a left-sided intraoral bulge. Otorhinolaryngological findings were otherwise normal; there was no evidence of cervical lymphadenopathy or any systemic symptoms.\nComputed tomography (CT) revealed a heterodense mass lesion measuring 8 × 7 cm at its greatest dimension causing bony destruction of the ascending mandibular ramus and with extension into the skull base. The tumor caused effacement of the fat and muscle planes of the infratemporal fossa and the masticator spaces. It was seen pushing the parotid space laterally and the parapharyngeal space medially. The left temporomandibular joint was obliterated by the tumor [–]. A bone scintigram showed an increased abnormal activity in the left side of mandible corresponding to the tumor []. A bone marrow aspiration and a bone marrow biopsy were within normal limits. An extraoral trucut biopsy from the tumor on histopathologic examination revealed a diffused collection of small malignant round to oval cells with hyperchromatic nuclei, inconspicuous nucleoli, with vacuolated to pale cytoplasm and high mitotic activity, and scattered blood vessels with peritheliomatous arrangements of the tumor cells. The tumor cells on immunohistochemistry were positive for vimentin, CD99, Bcl2, chromogranin, and S-100. It was negative for keratin, LCA, CD3, CD 20, CD56, and Alk 1. Fifty percentage of the tumor cells showed strong nuclear positivity to Ki-67. The histopathology along with immunohistochemistry correlation favored a diagnosis of PNET of the mandible [–].\nThe patient was planned for a multimodality treatment. She initially received four cycles of vincristine, adriamycin, cyclophosphamide alternating with ifosfamide and etoposide (VAC/IE) based chemotherapy. In view of the extensive soft tissue involvement, she was initially considered for external beam radiotherapy as a part of her local therapy. A static response was noted after 54 Grey (Gy) of radiotherapy, which was confirmed on a subsequent CT of the mandible which showed a necrotic residue with patchy contrast uptake. She was subsequently taken for a definitive surgery after the sixth cycle of chemotherapy. En bloc excision of the tumor along with a posterior segmental mandibulectomy from the level of left first molar to left condyle and left temporomandibular joint was done [–]. An ‘L’ shaped reconstruction plate was anchored to the zygoma and the remnant mandible to bridge the bony defect, soft tissue cover was achieved by an anterolateral thigh free flap. [Figures and ] The postoperative histopathology revealed no viable tumor and a 100% tumor necrosis. She further went on to complete her further courses of chemotherapy and is presently disease free.