A 13-year-old male presented with a rapid enlarging painless diffuse mass located at the right midface and parotid region over the last 6 months. Slight asymmetry of the right commissure, trismus and mandibular asymmetry were evident on initial examination. There were no evidences of regional or distant metastasis. Past medical history included a previous surgical treatment attempt in his native country Honduras, three months prior to his referral (Fig. A). T1 weighted MRI showed a large hyperintense mass measuring 7 x 5 cm, located centrally at the right masticator space with extention into the mandibular ramus, masseter and pterigoyd muscles, parotid gland and parapharyngeal space. Contrast T2 weighted MRI exhibited a high signal with a multinodular and infiltrative pattern (Fig. B).\nAn incisional intraoral biopsy was performed under local anesthesia. The histopathological examination revealed multiple nodules containing tumor cells, immersed in an abundant myxoid stroma separated by fibrous septae. The tumor cells varied in shape from round to elongate, most displaying abundant eosinophilic cytoplasm and round to ovoid excentrically located nuclei, which showed homogeneously distributed chromatin and inconspicuous nucleoli. Other cell types were recognized, mainly spindle, epithelioid and lipoblast-like cells (Fig. ). The mitotic rate was low, averaging two mitotic figures per 10 high-power fields. Periodic acid-Schiff (PAS), with and without prior diastase digestion, demonstrated that the granular cytoplasmic material was glycogen. Immunohistochemical analysis (), showed positivity for vimentin, neuron-specific enolase (NSE), and chromogranin; whereas AE1/AE3, epithelial membrane antigen (EMA), S-100, desmin, muscle-specific actin (HHF35), CD57, Glucose transporter type 1 (Glut-1), synaptophysin, p53, p63, glial fibrillary acidic protein (GFAP), and podoplanin (D2-40) were negative. The Ki-67 labelling index was 42% after evaluation of 1000 cells per five high-power fields (Fig. ). Fluorescent in situ hybridization was not performed; however, the histomorphological and immunohistochemical findings supported a final diagnosis of EMC.\nThere were no evidences of regional or distant metastases, and the patient was treated with en-bloc surgical resection, including ipsilateral hemi-mandibulectomy, total parotidectomy with facial nerve dissection, neck dissection level I to IV and reconstruction with a mandibular plate and major pectoralis flap. Macroscopically, the specimen measured 8 x 6 x 5 cm consisting of an irregularly shaped mass attached to the mandibular ramus, with a multilobular and gelatinous rubbery tissue. Focally, the tumor was present in one surgical margin, immediately anterior to the mandibular condyle. Microscopic evaluation revealed the same histopathological features found in the incisional biopsy. The patient received adjuvant radiotherapy but died after 1 year of follow-up due to complications of locoregional tumor dissemination to the skull base.
A 10-year-old boy presented with bloody rhinorrhea of one month duration from the right side of the nasal cavity. On nasal endoscopy, a large, polypoid mass was observed to fill the right nasal cavity causing deviation of the lateral nasal wall to the right. CT showed a lobulated, low attenuating mass with ring and arc calcifications in the right nasal cavity and nasal septum, measuring about 4.9 ×3.3 ×2.9 cm (). The mass extended beyond the nasal septum into the right ethmoid sinus and had caused pressure erosion of the adjacent bony margins of the cribriform plate and medial orbital wall. However, no definite bony destruction was demonstrated. After intravenous infusion of contrast medium, subtle internal septal enhancement of the mass was observed. Coronal and axial T2-weighted MR images (TR/TE, 4128/100) revealed more accurately the anatomical relationships of the mass (), which was located in the right nasal cavity and nasal septum, and extending into the right ethmoid sinus. The mass had displaced and compressed the right medial orbital wall laterally and the cribriform plate superiorly, and mass was homogeneously hypointense on T1-weighted images () and heterogeneously hyperintense on T2-weighted images (). It showed mainly peripheral and septal-like enhancement on contrast-enhanced T1-weighted images and regional inhomogeneously strong enhancement at its anterosuperior portion (). Areas of low signal intensity were seen on T2-weighted MR images (), which corresponded to matrix mineralization on CT images (). An endoscopic biopsy was performed in the nasal cavity, and the preliminary pathologic diagnosis was of myxoid chondrosarcoma or chordoma, due to the presence of a cord-like cellular arrangement with a myxoid background. Whole body PET-CT with a low-dose CT protocol was performed at the 17th day after biopsy. PET-CT revealed a mild F18-fluorodeoxyglucose (FDG) uptake area (pSUV, peak standardized uptake value = 2.7) in the lesion without a definite metastatic lesion ().\nThe patient underwent subtotal resection of the mass; some residual mass remained in the ethmoid sinus and nasal septum. The removed tumor was a pale gray, soft to firm, polypoid mass measuring 4.7 ×3.0 ×3.0 cm. Histologically, there were scattered pleomorphic chondroblasts with thin anastomosing strands surrounded by a myxoid stroma; cellular areas were arranged in cords (). The presence of a characteristic cord-like cellular arrangement resembling chordoma and strong positivity for S-100 protein and vimentin led to a final diagnosis of myxoid chondrosarcoma. The low cellular atypia, few mitoses, and low cellularity observed represented a low grade tumor. We could not prove the presence of the specific t (9; 26) translocation which is regarded as another pathognomonic feature of myxoid chondrosarcoma because the RT-PCR technique and primer required were unavailable.\nAfter surgery, the patient underwent radiation therapy on the remaining primary tumor, and subsequently the remaining tumor showed a decreased size and enhancement on follow up CT.