両側網膜芽細胞腫既往を伴った鼻腔原発平滑筋肉腫例 Primary Nasal Leiomyosarcoma Case with Past History of Bilateral Retinoblastoma
We report a case of leiomyosarcoma in the nasal cavity of a patient with a history of bilateral retinoblastoma.<br>Leiomyosarcomas account for 7% of all soft tissue sarcomas, and they usually develop in smooth-muscle-rich organs such as the uterus, urinary bladder, and gastrointestinal tract, but they also occur at other sites, including the extremities, retroperitoneal space, mesenteries, kidneys, liver, orbits, pancreas, spleen, femoral veins, and heart. Most malignant tumors of the nose and the paranasal sinuses are carcinomas, and the incidence of sarcoma is low; leiomyosarcoma is even rare among the sarcomas in these regions. To the best of our knowledge, only 27 cases, including our own, have been reported in Japan.<br>The patient was a 51-year-old male with a chief complaint of nasal obstruction. He had experienced nasal obstruction on the left side since about May 2004, and was told of the presence of a tumor filling the nasal cavity when he consulted a local otorhinolaryngologist. A CT scan showed a homogeneous tumor filling the inferior nasal meatus on the left, and the tumor was endoscopically removed towards the end of August. Because leiomyosarcoma was diagnosed as a result of istological examination, extirpation of the tumor was performed via the maxilla in the middle of September. Two cycles of a CYVADIC protocol were given postoperatively as adjuvant chemotherapy. There is no evidence of recurrence or metastasis at present.<br>Retinoblastoma occurs when the Rb1 region is deleted in one of the responsible alleles and point mutation occurs in responsible alleles or when point mutation occurs in both of the responsible alleles. Patients with a history of retinoblastoma are known to manifest other primary tumors secondarily. These tumors are thought to develop because of a mutation in the Rb1 gene caused by irradiation, a genetic mutation or other factors that reduce the tumor suppressing function of the body. Osteosarcoma accounts for as much as 50% of sarcomas in patients with both a retinoblastoma and soft tissue sarcoma, but the incidence of leiomyosarcoma is very low. As far as we have been able to determine in a search of the literature in Japan and abroad, this condition has only been reported in the liver in one case and in the urinary bladder in two cases. Thus, this is the first report of a case in which primary leiomyosarcoma developed in the nasal cavity of a patient with a history of retinoblastoma. Because radiation therapy had previously been used in our case, we suspected that the leiomyosarcoma had developed secondarily to a gene-related abnormality such as that of the Rb gene.
耳鼻咽喉科臨床 99(8), 647-652, 2006-08-01
The Society of Practical Otolaryngology