Background:
Spindle cell sarcoma is a broad general term for malignant tumors originating from soft tissues, such as fat, muscle, blood vessels, nerves, and tissues surrounding bones. Spindle cell sarcoma is uncommon and among all primary soft tissue and bone malignancies, it accounts for less than 10%. It is more likely to occur in adults over 40 years old and on long bones, such as femurs and tibias. Symptoms are usually not obvious and are mostly manifested by swelling and pain. Treatment usually includes surgical resection, chemotherapy and radiation therapy.

Patient and Methods:
This study discusses a case of a six-year-old boy with spindle cell sarcoma of the right zygomatic bone, which was manifested by right cheek bone bulging mass and diagnosed through sono-guided biopsy. Neoadjuvant chemotherapy was administered with ifosfamide and doxorubicin. In surgical planning, preoperative computed tomography imaging was used to identify the tumor location. Safe margin was further marked in the computer software after discussion with the radiologist, to achieve complete tumor resection and retain as much healthy tissue as possible. A 3D model skull made of polylactide (PLA) thermoplastic was used to simulate the location of the tumor and was used as a reference either in pre- and intra-operative period. In combination with photosensitive resin, which is a 3D printing material used in stereolithography technology and was used to print surgical guide jigsaw puzzle model, accurate osteotomy through minimally invasive wounds was achieved through extended transconjunctival approach and upper gingivobuccal sulcus incision. Resected tumor-containing bone segment was treated with cryotherapy (liquid nitrogen) to eradicate tumor cells and later re-implanted as frozen autograft for biological reconstruction of the zygomatic bone.

Results:
In 3 months follow up, symmetry of bilateral malar height with a scarless appearance was achieved. There was no facial functional deficit. Facial bone plain film revealed bone healing and whole body PET/CT showed no obvious uptake in previous right zygomaticomaxillary junction enhancing lesion, suggesting metabolic complete remission.

Conclusion:
In the field of facial bone tumors treatment, the combination use of three dimensional printing surgical guide jigsaw puzzle model and cryotherapy allow minimally invasive tumor excision and autologous reconstruction. The case is presented to provide a reference doable method for the treatment of similar clinical cases in the academic community.

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