Case 333: Masson Tumor

History A 61-year-old male patient without prior history of ophthalmologic problems presented with pain and redness in the left eye associated with slowly progressive proptosis over the previous 6 months. The patient also had diplopia in rightward and downward gaze. There was no vision loss. Mild fullness was seen in the periorbital tissues without any redness or fluctuance and with no purulent discharge from the left eye. The patient was otherwise healthy, with a 6-year history of diabetes mellitus and an 8-year history of hypertension managed well with medication. There was no history of trauma to the head or face. At clinical examination, conjunctival edema and redness with proptosis were noted. The cornea was clear. Evaluation of eye movements revealed restricted motion of the left eye in medial gaze and downward gaze. Ophthalmoscopic evaluation did not show any substantial abnormality. The retina and retinal vascularity were unremarkable. The right eye was unremarkable. Uncorrected visual acuity was 20/30 in the right eye and 20/40 in the left eye. Corrected visual acuity was 20/20 in both eyes. Complete blood cell count, as well as liver and kidney function test results, were within normal limits. The erythrocyte sedimentation rate and C-reactive protein level were normal. Thyroid function test results were normal. The patient subsequently underwent CT of the orbits without and with contrast enhancement followed by further evaluation with MRI of the orbits without and with contrast enhancement.