Plasmacytoma of Nasopharynx - A Rare Case Presentation Treated with Volumetric Modulated Arc Technique Radiotherapy

[摘要] Giant cell tumors (GCTs) of bone constitute 3%–5% of all the bone tumors. GCTs are uncommon, locally aggressive, osteolytic neoplasms commonly seen in early adulthood. Involvement of cranial and facial bones is rare and comprises 2% of all the cases. Sphenoid and temporal bones are the most common sites of GCTs in head and neck. Although complete resection may not be possible, feasibility of partial resection depending on the extent and involvement of critical structures should be the best alternative. GCTs, though historically considered radioresistant, have a dose-dependent effect. This is a case report of a 20-year-old male, who presented with headache, blurring of vision in both the eyes, and diplopia for 2 months. Magnetic resonance imaging (MRI) showed a 4.5 cm × 3.4 cm × 3.5 cm lesion involving superior body of clivus, sphenoid sinus, and floor of sella, adherent to anterior pituitary gland along the superior aspect, indenting optic chiasm with extrinsic compression and bulging into bilateral cavernous sinuses. The patient underwent endoscopic transnasal partial resection of the lesion. Histopathological examination showed tissue containing numerous osteoclasts such as giant cells separated by round to spindle-shaped mononuclear cells. On immunohistochemistry, the giant cells were positive for CD 68 with Ki 67 proliferation index about 15%–20% in highest proliferating areas. The patient underwent definitive radiation treatment to a radiation dose of 55 Gy in 31 fractions over 6 weeks. The patient tolerated treatment well with minimal toxicities, his vision improved by the end of treatment. The patient needs to be assessed for radiological response and late side effects. GCTs of the skull are rare benign osteolytic locally aggressive lesions generally seen in early adulthood. En bloc surgical resection is the treatment of choice but has high local recurrence rates. Radiation is the treatment of choice in unresectable, partially resected, and recurrent tumors. With the advent of advanced techniques such as intensity-modulated radiotherapy/volumetric-modulated arc therapy, better dose distribution can be achieved in the target minimizing dose to the critical structures. Imaging with daily kilovolt cone-beam computed tomography is essential in the treatment of tumors of the skull for precise treatment delivery.

[学科分类] 药学

[关键词] Giant cell tumor;radiation treatment;volumetric modulated arc therapy