Solitary Extramedullary Plasmacytoma in the Oropharynx: Advantages of Intensity-Modulated Radiation Therapy

We report a case of a 59-year-old man with solitary extramedullary plasmacytoma in his oropharynx. Because the diagnosis is rare and there is only limited experience in the literature based on retrospective data, the optimal planning target volume and optimal dose of radiation therapy (RT) are still controversial. The frequently discussed problem is the necessity of first echelon lymph node irradiation because it is associated with a higher rate of complications such as xerostomia caused by damage to salivary glands. In order to prevent late toxicity, intensity-modulated RT with the use of simultaneous integrated boost and parotid salivary gland sparing was used in this patient's treatment. The RT was performed in 23 identical fractions, the primary tumor region was irradiated with a dose of 46 Gy and the first echelon lymph node region with the risk of subclinical disease with a dose of 41.4 Gy; the dose per fraction was 2 Gy and 1.8 Gy, respectively. The patient is alive and well > 20 months after the irradiation, without any evidence of disease. Parotid gland function remained intact, and no xerostomia occurred. This is the first report of the use of intensity-modulated RT with parotid gland sparing in the treatment of solitary extramedullary plasmacytoma in the head and neck region.