[Extraskeletal myxoid chondrosarcoma: a report of 5 cases and review of literature].
OBJECTIVE
To study the clinicopathologic features, immunophenotype and differential diagnosis of extraskeletal myxoid chondrosarcoma (EMC).


METHODS
The clinicopathologic features of 5 cases of EMC (during the period from 2008 to 2013) were retrospectively analyzed. Immunohistochemical study (EnVision method) was carried out using the archival material. The literature was reviewed.


RESULTS
There were altogether 3 female patients and 2 male patients. Their age ranged from 38 to 63 years (average = 51 years). The patients primarily presented with a tender soft tissue mass. All the tumors studied were solitary and the duration of disease onset varied from 3 months to 1 year. The sites of involvement included toe (number = 2), intracranial (number = 1), thigh (number = 1) and shoulder (number = 1). Gross examination showed white nodular masses with a gelatinous cut surface. The average tumor size measured 5.2 cm in greatest dimension. Histologically, a multinodular architecture with fibrous or loose fibrovascular septa separating lobules of tumor cells was identified. The lobules contained abundant myxoid stroma, with peripheral accentuation of tumor cellularity. Two cases were diagnosed as cellular variant of EMC, with invasive growth pattern and hemorrhage. The tumor cells in cellular EMC were arranged in solid nodules, with rare myxoid matrix in between. The nuclei were relatively uniform, round to oval and contained prominent nucleoli. The mitotic figure ranged from 5 to 10 per 10 high-power fields. Immunohistochemical study showed that all of the 5 cases were positive for vimentin, mitochondria and CD56. Two cases expressed synaptophysin and NSE. Focal positivity for these neuroendocrine markers was detected in the other 2 cases. Chromogranin and S-100 protein expression was demonstrated in 2 cases. The staining for epithelial membrane antigen was positive in case 2 and negative in the other 4 cases. CD117 showed diffuse positivity in case 1, the other 4 cases were not expressed.


CONCLUSIONS
EMC is a rare soft tissue sarcoma characterized by distinctive histopathologic features and often shows neuroendocrine differentiation. Although EMC is a slow-growing tumor, it carries a high local recurrence rate and even metastases, warranting long-term follow up.
Department of Pathology, Xi Jing Hospital, the Fourth Military Medical University, Xi'an 710032, China.
Hong
H
Xu
Department of Pathology, Xi Jing Hospital, the Fourth Military Medical University, Xi'an 710032, China.
Changwei
C
Yang
Department of Pathology, Xi Jing Hospital, the Fourth Military Medical University, Xi'an 710032, China.
Yingmei
Y
Wang
Department of Pathology, Xi Jing Hospital, the Fourth Military Medical University, Xi'an 710032, China. E-mail:yangsj@fmmu.edu.cn.
Shoujing
S
Yang
D000328:Adult; D019002:CD56 Antigen / Q000378:metabolism; D002813:Chondrosarcoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D002817:Chordoma / Q000378:metabolism / Q000473:pathology; D002864:Chromogranins / Q000378:metabolism; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018204:Neoplasms, Connective and Soft Tissue / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D012189:Retrospective Studies; D012208:Rhabdomyosarcoma / Q000378:metabolism / Q000473:pathology; D009418:S100 Proteins / Q000378:metabolism; D012782:Shoulder; D016708:Synaptophysin / Q000378:metabolism; D013848:Thigh; D014034:Toes; D014746:Vimentin / Q000378:metabolism*
D019002:CD56 Antigen; D002864:Chromogranins; D009418:S100 Proteins; D016708:Synaptophysin; D014746:Vimentin; D010751:Phosphopyruvate Hydratase