Diplopia with a cavernous sinus metastasis of a remote endometrial stromal tumour

Structural lesions involving the visual pathways often require tissue diagnosis to guide therapy. However, pathology is not always definitive, and a biopsy showing poorly differentiated cells poses significant difficulty in identifying the primary tumour. We report a case of metastatic disease causing cavernous sinus syndrome, in which biopsy revealed poorly differentiated tissue. The patient reported a history of a resected uterine tumour, and it was only after obtaining slides from 7 years prior that the diagnosis was made.