Abstract
Purpose :
Malignant solitary fibrous tumor (SFT) of the orbit is an extremely rare spindle cell neoplasm with only three reported cases in the literature. We present an additional case using contemporary immunohistochemical stains and report on the latest World Health Organization (WHO) classification of this tumor.
Methods :
A 65 year old male presented with right-sided proptosis. Best corrected visual acuity was 20/40 and 20/25 in the right and left eyes, respectively. Pupils, confrontational visual fields, slit lamp evaluation, and dilated fundus exam were normal. Right eye adduction was limited and external examination revealed right-sided ptosis, lateral globe displacement, and cheek festooning. Neuroimaging was notable for a 2.2 cm, extraconal heterogeneous mass that diffusely enhanced.
Results :
Initial orbital biopsy identified SFT and was followed by en-bloc tumor resection. Malignant SFT was diagnosed based upon nuclear atypia, hypercellularity, and increased mitotic activity (13 mitotic figures/10 high powered fields). Immunohistochemical analysis stained positive for CD 34 with partial lack of staining within the malignant portion, and negative for CAM 5.2, desmin, actin, CD 31, and CD 117. S-100 and Stat6 were positive in the malignant portion but negative in the benign counterpart of the tumor. Ki-67 showed 2% nuclear staining in the benign tumor and 10-15% staining in the malignant counterpart.
Conclusions :
Immunoprofiling is critical to making the diagnosis of malignant solitary fibrous tumor of the orbit. Complete tumor resection continues to be the preferred treatment. The role of adjuvant chemotherapy and orbital radiation remains controversial. The behavior of extrathoracic SFT is unpredictable, and patients with SFT in all locations require careful, long-term follow-up.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.