Abstract: OBJECTIVE: To study the diagnosis and treatment of FDCS of the jaws. METHODS: A patient with FDCS occurring in the mandible was seen, and a review of the relevant literature was conducted through consultation and specialist examination, combined with radiographic CT examination and pathological examination. RESULTS: The diagnosis of FDCS of the jaws was initially clarified, and a preliminary design of treatment was proposed and used for clinical treatment. CONCLUSION: Follicular dendritic cell sarcoma is a rare hematopoietic tissue tumor of lymphoid follicular dendritic cell origin, which has not been reported in the jaws at home and abroad, and this case should be the first one. The main clinical manifestation of this tumor in the mandible is numbness of the lower lip with toothache, and imaging shows bone resorption without obvious root resorption. The main features are CD21(+), CD35(+), CD1α(-), SMA(-) and EBV(-). Treatment was surgical partial osteotomy with radiotherapy. Keywords: histiocytic tumor; follicular dendritic cell sarcoma; malignant tumor of jaw bone; diagnosis and treatment Follicular dendritic cell sarcoma (FDCS), also known as dendritic reticular cell sarcoma, is a rare hematopoietic tissue tumor of lymphoid follicular dendritic cell origin. Since it was first described by Monda.L [1] in 1986, more than 60 cases have been reported worldwide. Clinically, it usually presents as superficial lymph node enlargement such as in the neck or axilla, but also as extra-nodal lesions, occurring in extra-nodal structures such as the oral cavity, pharynx, and liver and intestine [3, 4, 8]. In our hospital, a case of FDCS in the mandible was diagnosed on February 25, 2007, and only a literature search revealed that follicular dendritic cell sarcoma occurring in the jaw bone has not been reported domestically or internationally. 1. Case presentation The patient was female, 37 years old. She was admitted to the hospital on February 25, 2007, mainly because of pain in the left lower teeth with numbness in the left lower lip for 3 months and a swelling in the left lower jaw for 1 month. History: The patient complained of persistent stabbing pain in the left lower posterior teeth without obvious cause three months ago, with severe pain at night, followed by numbness of the left lower lip. Azithromycin” anti-inflammatory treatment, and supplemented with local heat. After treatment, the toothache improved, but the numbness of the lower lip persisted. One month ago, the pain in the left lower back tooth appeared again, and the numbness still persisted and did not change significantly from before, so he went to the local hospital and had a CT examination, which showed that “the left mandibular bone was destroyed”. At present, the patient is in good general condition, with normal diet, urination and defecation, and no general chills and fever. Maxillofacial examination: a swelling of about 3.0×2.0×2.0 cm3 was palpable in the left mandible, with hard texture, no motility, no pressure pain, no high surface skin temperature, and no red skin. The left lower lip was painless with numbness, and the left lower first molar was missing in the mouth, and the first two bicuspids were biting the jaw filling. No redness or swelling was seen at the mouth of each salivary gland duct, the secretion was clear, the pharynx was not red or swollen, and the tonsils were not large. No obvious enlarged lymph nodes were found in the submaxilla and neck bilaterally. Conventional surface tomography showed bone destruction of the jaws and extension of the inferior alveolar nerve canal, with no obvious bone white lines and root resorption at the edges of the bone destruction and no obvious periosteal reaction; CT examination showed worm-like bone destruction of the mandible with irregular bone resorption. The patient had an early history of dental pain, which was characterized by persistent stabbing pain in the teeth and numbness of the lower lip as the main symptom. He was treated for pulpitis developing into osteomyelitis after consultation. The treatment was not effective. Based on the patient’s medical history and imaging data, a malignant tumor of the mandible was initially considered as a high possibility. After discussion, the surgical approach was prepared to take a biopsy first, and a rapid frozen section was taken to guide the surgery. During the operation, we saw that the tumor tissues were growing from the chin hole outward to the jaw bone, and the bone around the chin hole was removed, and we saw that the tumor extended along the inferior alveolar nerve canal, but there was no trend of growth toward the buccolingual direction, and no obvious osteolytic manifestation was seen, which was different from the typical manifestation of central carcinoma of the mandible. Some tissues were taken and sent for rapid frozen section. The pathology department considered that this patient had special pathological results, and after the whole department discussion, the conclusion showed that “epithelial-like tumor tissue (left mandible) with obvious cell heterogeneity and easy to see nuclear fission images, considering the possibility of malignancy, not excluding lymphopoietic system origin”. According to the results of rapid freezing, the bone wall was removed by biting, the mass was scraped out, the inner part of the bone wall was scraped, the bone around the mass was bitten off about 1.0 cm, and the whole bone cavity was removed with a grinding head to remove 2 mm of bone, and the lower edge of the mandible was preserved. Afterwards, the swelling and the occluded bone were sent to pathology. Subsequently, the pathology department concluded that “the normal structure of the mandibular bone marrow was destroyed and replaced by diffuse infiltration of epithelioid histiocytes and spindle cells, some areas were rich in nuclear schizophrenia with fibrosis, and immunohistochemical staining showed tumor cells: CD35 (few weak +), CD21 ( few weak +), CD68(+), CD1a(-), CD3(-), CD20(-), PAX-5(-), CD30(-), CD45RO(-), LCA(+), S-100(individual +), SMA(-), CD79a(-), PAX-5(-), MPO(-), CD30(-), EBV(-) Ki-67 (+ 25-50%) were considered to be low-grade malignant tumors of histiocytic origin, with inflammatory pseudotumors and follicular dendritic cell sarcomas to be further excluded. Based on the malignant manifestation of the pathological findings, a second surgery was planned after discussion in our department, and the surgical approach was guided by the surgical approach for malignant tumors of the jaws, i.e., partial osteotomy of the mandible, free iliac bone grafting, and reconstruction plate fixation. The patient’s facial shape did not change significantly after the operation. 2. Discussion FDCS is an extremely rare malignant tumor among hematopoietic tumors, and no specific clinical manifestation of this disease was seen. The discovery of follicular dendritic cell sarcoma in the jaw bone in our hospital should be the first case at home and abroad. The main clinical manifestation of this patient was toothache and numbness of the lower lip, and it was similar to the clinical manifestation of central jaw cancer. The early clinical symptoms include toothache and numbness of lower lip, and the growth rate is fast; it develops from the bone marrow to the dense bone, and then expands to the buccolingual side after penetrating the bone to form a mass or invades the alveolar process to cause loosening and loss of teeth, and can invade the opposite side according to the direction of the inferior alveolar nerve canal. Central carcinoma of the jaw bone shows irregular worm-like destruction in the apical region, and then invades the dense bone and is often accompanied by root resorption. The early manifestation of follicular dendritic cell sarcoma in jaw bone is very similar to that of central carcinoma of jaw bone, but the patient does not have the characteristics of rapid growth, no obvious expansion in the buccolingual direction, no local tenderness and no resorption of tooth roots among the X-ray manifestations. Such clinical features made the diagnosis difficult, so the final diagnosis had to be made by immunohistochemistry. In 2002, the International Lymphoma Study Group (ILSG) recommended a panel of antibodies against CD21, CD35, CD1a, S100, CD68, and lysozyme (LYS) as routine primary screening antibodies for histiocytic and dendritic tumors based on immunohistochemical analysis of 61 cases of histiocytic and dendritic tumors. +, CD1a-, S100±, CD68-, LYS- [5, 6]. However, FDCS cells are generally negative for CD20, CD1a, myeloperoxidase, CD34, CD79a, CD30 and leukocyte common antigen . The mature small lymphocytes surrounding the tumor cells usually express a B-cell phenotype (CD20 +, CD79a + ), a few express a T-cell phenotype (CD3 + ), and individually express a mixed B- and T-cell phenotype [ 2, 8 ]. The immunohistochemistry of this patient showed CD35 (+), CD21 (+), CD68 (+), CD1a (-), CD3 (-), CD20 (-), PAX-5 (-), CD30 (-), CD45RO (-), LCA (+), S-100 (individual +), SMA (-), CD79a (-), PAX-5 (-), MPO (-), CD30 (-), EBV (-), Ki-67 (+ 25-50%). We determined that the patient should be diagnosed with FDCS based on the standard FDCS immunohistochemical data presentation. Treatment options for patients with FDCS remain controversial, and the place of surgery, radiotherapy and chemotherapy in their management has not been clarified [2, 3, 7, 9]. Surgical resection has been the treatment of choice for limited lesions of FDCS and can be combined with radiotherapy. It has been reported [1, 9] that 12 of 31 patients with FDCS who underwent surgery alone had recurrence after surgery, but 6 of 8 patients with FDCS who underwent surgery combined with radiotherapy survived with a median disease-free survival of 36 months (7-66 months). Currently, most of the malignant tumors of the jaws are treated surgically, often by partial osteotomy, square resection, etc., and postoperative radiotherapy is also recommended in combination with chemotherapy. According to the previous treatment of FDCS, surgery is also preferred for this patient, and considering that the patient is a malignant tumor of the jaw bone, the final specific way of surgery is to osteotomy 1.5 cm outside the tumor and free iliac bone graft repair, which has good repair effect. The main clinical manifestation of FDCS occurring in the jaw is numbness of the lower lip. If there is a patient whose main symptom is lower lip numbness or even had a toothache. In addition to the diagnosis of central carcinoma of the jaw, the possibility of follicular dendritic cell sarcoma may also be considered. The pathologic diagnosis of follicular dendritic sarcoma relies on typical immunohistochemistry, which is characterized by CD21+, CD35+, CD1a-, S100±, CD68-, and LYS-. The treatment of follicular dendritic cell sarcoma is still in the exploratory stage and there is a lack of effective protocols. Follicular dendritic cell sarcoma occurring in the mandible can be treated surgically in the same way as other low-grade malignant tumors of the jaw bone histiocytes, with segmental osteotomy, autologous bone free grafting, and can be combined with radiotherapy after surgery. References: 1. Monda L, Warnke R, Rosai J. A p rimary lymph node malignancy with features suggestive of dendritic reticulum cell differentiation: a report of 4 Am J Pathol, 1986, 122. Am J Pathol, 1986, 122: 562 – 565. 2. Perez-Ordonez B, Erlandson RA, Rosai J. Follicular dendritic celltumor: report of 13 additional cases of a distinctive entity[ J ]. distinctive entity[ J ]. Am J Surg Pathol, 1996, 20: 944 – 950. 3. Fonseca R, Yamakawa M, Nakamura S, et al. Follicular dendritic cell sarcoma and interdigitating reticulum cell sarcoma: a review[J].Am J Hematol, 1998, 59(2): 161-167. 4. Biddle DA, Ro JY, Yoon GS, et al. Extranodal follicular dendritic cell sarcoma of the head and neck region: three new cases, with neck region: three new cases, with a review of the literature[J]. Mod Pathol, 2002, 15(1):50-58. 5. Sun X, Chang KC, Abruzzo LV, et al. Epidermal growth factor recaptor expression and Castleman’s disease[ J].Hum Pathol, 2003, 34(9): 835-840. 6. Pileri SA, Grogan TM, HarrisNL, et al. Tumours of histiocytes and accessory dendritic cells: an immunohistochemical approach to classification immunohistochemical approach to classification from the Intemational Lymphoma Study Group based on 61cases[J]. Histopathology, 2002, 41(1): 1-29. 7. Chen JK, Fletcher CD, Nayler SJ, et al. Follicular dendritic cell sarcoma: clinicopathologic analysis of 17 cases suggesting a malignant potential higher than currently recognized[J].Cancer, 1997, 79:294-298. 8. MartinsMT, Witzel AL, SugayaNN, et al. Dendritic cell sarcoma of the oral cavity[J].Oral Oncol, 2004, 40(3):341-347. 9. Fonseca R, Tefferi A, Strickler JG, et al. Follicular dendritic cell sarcoma mimicking diffuse large cell lymphoma: a case report[J]. Am J Hematol, 1997, 55: 148-152.