Orbital hyalinizing spindle cell tumor with giant rosettes

To evaluate the clinical and histopathologic characteristics of orbital hyalinizing spindle cell tumor with giant rosettes (HSCTGR).

Interventional case series of 2 patients, aged 4 and 9 years referred to the Ocular Oncology Unit. Both patients presented with slowly progressive proptosis with dimness of vision in the second patient. CT was performed for both patients followed by excision of the masses. Histology was performed on tissue sections.

CT revealed a localized tumor in the first case and extensive mass extending to the optic canal in the second patient. Histologic analysis revealed features of HSCTGR with characteristic spindle-shaped cells with giant rosettes with hyalinized foci. Tumor cells were positive for vimentin in both cases and focal S100 positivity in first case. However, the second case showed a higher Ki-67 index compared to the first case, suggestive of moderately high proliferative activity. After excision, neither of the tumors demonstrated local recurrence, and both patients were without regional or distant metastases. Mean clinical follow-up was 12 months.

HSCTGR involving the orbit has not been previously reported in the literature. We report 2 cases of orbital presentation at a much younger age than has been shown in patients with this type of tumor in other areas of the body. Complete excision of this tumor with close follow-up is the preferred treatment. HSCTGR should be considered in the differential diagnosis of orbital fibrous tumor presenting as painless progressive proptosis.