Recently, computer-assisted surgery （CAS） has been applied in mandibular bone reconstruction. In this study, we compared the reproducibility, efficiency, and postoperative complications of CAS （TruMatch^Ⓡ） and non-CAS re­con­struc­tive surgery （freehand surgery） in order to verify the efficacy of CAS in fibular free flap reconstruction of the mandible.
Fourteen patients who underwent mandibular reconstruction with fibular free flap from April 2017 to May 2023 were evaluated. Ten patients underwent freehand surgery （9 males and 1 female; median age, 65 years; age range 52-76） and four patients underwent TruMatch^Ⓡ surgery （3 males and 1 female; median age, 59 years; age range 48-66 years）. Mean difference in pre- and postoperative mandibular angle was 16.2 degrees for freehand surgery and 2.6 degrees for TruMatch^Ⓡ, with TruMatch^Ⓡ being significantly smaller. TruMatch^Ⓡ had a shorter reconstruction time than freehand surgery compared with the same number of bone segments. Postoperative complications such as plate fracture were observed in 7 of 10 patients with freehand surgery. In contrast, no such complications were observed with TruMatch^Ⓡ.
These results suggest that mandibular bone reconstruction using CAS is useful in improving reproducibility of mandibular form, shortening the time required for reconstruction, and reducing postoperative complications related to the plate.

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Patients with hematopoietic malignancies who have undergone hematopoietic stem cell transplantation （HSCT） are prone to develop oral cancer. We have experienced four cases of oral cancer after HSCT. In this study, we examined 47 cases, including 43 cases reported in Japan and our four cases.
The hematopoietic malignancies of the four patients were two cases of acute myelogenous leukemia, a case of myelodysplastic syndrome, and a case of follicular lymphoma. Two patients underwent peripheral blood stem cell transplant, one patient underwent bone marrow transplant, and one patient underwent cord blood transplant. Two of the four patients developed chronic oral GVHD after HSCT. Three patients underwent surgery, and one patient underwent definitive radiotherapy for oral cancer. The prognosis was that only one patient survived; the remaining patients died of oral cancer, hematologic diseases, and other causes.
A review of the literature found that 24.2％ of patients with oral cancer occurring after HSCT died within 5 years of diagnosis. In addition to recurrence and metastasis, the incidence of multiple cancers in the oral cavity was high, with 11 cases （33.3％）, suggesting the need for strict follow-up. Sequelae of HSCT such as bronchiolitis obliterans and a history of total-body irradiation may limit the treatment of oral cancer, so close follow-up is necessary to enable treatment to be started at an early stage of carcinogenesis.

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Malignant tumors rarely cause leukocytosis by producing granulocyte-colony stimulating factor （G-CSF）. In this report, we describe a case of G-CSF-producing tongue cancer that developed rapidly and manifested after recurrence. An 83-year-old woman presented with a chief complaint of a mass on the left lateral border of the tongue. Squamous cell carcinoma was revealed by histopathological examination, and a left partial glossectomy was performed 1 month after the initial diagnosis. Contrast-enhanced computed tomography performed 4 months after surgery revealed metastasis in the left mid internal jugular node region, and a left radical neck dissection was performed. The histopathological examination revealed one metastatic lymph node with intracapsular invasion. Six months after the neck dissection, a recurrence was observed in the left neck, with involvement of the periphery of the carotid artery and skin of the neck. Further surgery was not indicated, and chemoradiotherapy was planned; however, the disease rapidly progressed, and the patient died 13 months after treatment initiation. The white blood cell count was within normal range until the cervical recurrence, but high afterward, ranging from 16,000 to 25,000/μl. Immunohistochemical staining with anti-G-CSF monoclonal antibody was positive in all biopsy, primary resection, and metastatic lymph node specimens. Based on these findings, we diagnosed this as a G-CSF-producing tumor that became apparent after cervical recurrence.

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