Primary orbital mesenchymal chondrosarcoma: a case report and literature review.
BACKGROUND
Mesenchymal chondrosarcoma (MC) is a subtype of chondrosarcoma, with an incidence varying from 1 to 8% of all chondrosarcomas. It is an aggressive neoplasm with a high tendency for late recurrence and occasional delayed distant metastasis. Orbital MC is very rare, and only approximately 30 cases have been described in the literature. We describe here one case of primary orbital MC.


METHODS
A 14-year-old boy without a past medical history presented with a 1-month history of progressive proptosis on the right eye. Computed tomography (CT) scans of the orbit revealed a right intraconic lesion, with areas of calcification. The lesion was excised. Histopathological analysis revealed that the tumor had a biphasic pattern, showing a combination of small cell malignancy and well-differentiated cartilage. Immunohistochemistry examination revealed a diffuse membrane expression of CD99 on the small cell malignancy; S-100 was positive only within the cartilage component. The patient received chemotherapy, and no metastatic disease was found at the 2-month follow-up.


CONCLUSIONS
Although rare, MC should be considered in the differential diagnosis of a well-circumscribed orbital lesion in young adults, especially when CT scans reveal areas of calcification within the tumor.
Odashiro
Alexandre Nakao
AN
Department of Ophthalmology, Sociedade Beneficente Santa Casa, Campo Grande, MS, Brazil. alexandrenakao@yahoo.com.br
Leite
Lívio Viana O
LV
Oliveira
Rodrigo Sanches
RS
Tamashiro
Camila
C
Pereira
Patrícia Rusa
PR
Miiji
Luciana N Odashiro
LN
Odashiro
Danilo Nakao
DN
Burnier
Miguel N
MN
D000071443:12E7 Antigen; D000293:Adolescent; D015703:Antigens, CD / Q000032:analysis / Q000096:biosynthesis; D002114:Calcinosis / Q000175:diagnosis; D002356:Cartilage / Q000378:metabolism / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000096:biosynthesis; D018211:Chondrosarcoma, Mesenchymal / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D003937:Diagnosis, Differential; D004358:Drug Therapy; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D059630:Mesenchymal Stem Cells / Q000378:metabolism / Q000473:pathology; D009918:Orbital Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D009418:S100 Proteins / Q000032:analysis / Q000096:biosynthesis; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D000071443:12E7 Antigen; D015703:Antigens, CD; C061828:CD99 protein, human; D015815:Cell Adhesion Molecules; D009418:S100 Proteins