Follicular Thyroid Carcinoma Presenting as Bilateral Cheek Masses
In April 2007, a 46-year-old woman was referred to the Department of Otorhinolaryngology, Seoul National University Hospital for evaluation and further treatment of bilateral huge cheek masses. The masses had grown intra-orally and filled the whole oral cavity, disturbing normal mastication so that the patient had lived on soft or fluid diet (). Although her dentist had recommended surgery 5 years earlier, she was reluctant of undergoing operation and had repeatedly delayed the surgery. Over the 5 years, the disease was aggravated and the size of the mass increased progressively with intra-oral bleeding occurring intermittently.\nImaging work-up including neck computed tomography (CT) scan and magnetic resonance imaging (MRI) was performed. Large bilateral masses showed strongly enhanced solid tumors originating from the mandible which resulted in expansile destruction and erosion of both sides of the mandilble (). These lesions extended from the body to the condyle of the mandible. Intra-oral mucosal deep tissue biopsy from the left side mass was conducted and it was reported as an inflamed granulation tissue with necrosis. Therefore, the initial diagnosis was presumed to be central giant cell granuloma. Incidentally detected thyroid nodules on the CT scan were studied with ultra-sonography guided fine needle aspiration (FNA) cytology and the results were simple benign nodules (). Though the cheek masses had locally destructive features, there was no evidence of malignancy. Due to the patient's hesitancy about having an operation, we initially tried intra-lesional triamcinolone injection rather than surgical resection. Intra-lesional steroid injection is the alternative treatment of central giant cell granuloma, especially in large lesions, which may compromise vital structures []. The patient was treated once a week with an injection of 40 mg of triamcinolone into both mandibular tumors. The triamcinolone injections were not effective except transient size reduction and the treatment was terminated after a total of 3 injections on each side. Due to continuous oral bleeding and the aggravated locally destructive feature of the lesion, we decided to surgically excise the mandibular masses. Since the lesion involved bilateral mandible widely, to avoid a functional deficit of the mandible, such as a mastication, we decided to perform a stepwise approach:\nThe larger left mass was excised with the mandible that resected from 1st premolar to condyle. The involved buccal mucosa was also resected upto anterior to the retromolar trigone. The mandible and the buccal mucosa were reconstructed with osteocutaneous free flap using the left fibula and a skin paddle of fibular flap, in order to minimize the functional deficit, the intact uninvolved condyle was re-aligned onto the reconstructed mandible. Surprisingly, the final pathologic diagnosis turned out to be highly differentiated thyroid malignancy with involvement of the mandibular bone and perimandibular soft tissue. Immunoreactivity for thyroid transcription factor-1 of the left mandibular tumor revealed thyroid origin of the tumor (). The thyroid malignancy was possibly either follicular or papillary carcinoma but due to the borderline feature of the mass, a definite diagnosis could not be made. Conclusively, we proposed that the remnant lesion on the other side of mandible would have the same pathology and also suggested two possible diagnoses. One was bilateral mandibular metastases of an occult thyroid malignancy. The other possible diagnosis was bilateral ectopic thyroid malignancies with normally located thyroid glands, less likely. Therefore, additional work-up procedures for the right side mass and distant metastasis were performed. Although the result of FNA from the right mandible mass was reported as no evidence of thyroid origin or malignancy, the thyroid gland and the right side mass were revealed as a thyroid malignancy and multiple bony metastases including lumbar spine and femur neck were detected on I-131 thyroid scan () and whole body fluoro-deoxyglucose positron-emissions-tomography (PET) (). Two weeks later after the first surgery, total thyroidectomy was performed for definite diagnosis of the disease and high dose radioactive iodine therapy (RAI). The thyroid nodule was revealed as follicular thyroid cancer (). The confirmative diagnosis was follicular thyroid cancer with systemic metastasis involving both sides of the mandibule. Although immediate high dose RAI should follow, endocrinologist recommended surgical resection of the remnant right mandibular mass in case of possible local complication by radioactive iodine accumulation during high dose RAI. Six months later, right side mandibulectomy with fibular free flap reconstruction was planned. During the 6 months, due to the risk of pathologic fracture, metastatic lesions in the lumbar and femur were treated with extra-beam radiotherapy, 24 Gy and 30 Gy respectively.\nThe second surgery, right side hemimandibulectomy and osteocutaneous free flap reconstruction using the right fibula was conducted 7 months later. In order to save the mastication ability of the patient, much care was taken to preserve the masseter and pterygoid muscles as much as possible (). During the postoperative 1 year, she has been treated two times with 200 mCi RAI. No evidence of local recurrence has been suspected. Mastication ability was saved without any problems and the postoperative aesthetic result was satisfying ().