Gastrointestinal stromal tumor (GIST) is the most common primary mesenchymal tumor. The most common metastasis sites are the liver and the surface of the peritoneum, orbital metastasis of GIST is very rare.
A 43-year-old woman was referred to the hospital. She presented with left eye proptosis and vision loss of about one month. She had undergone surgical resection of a small intestinal stromal tumor in and partial resection of liver metastatic tumors .
In the ophthalmic examination, the visual acuity was 20/20 in her right eye and 20/40 in her left eye. The intraocular pressure was right eye,16.0 mmHg, left eye, 25.0 mmHg. External examination revealed a left proptosis of 6 mm. Ocular movement was limited in all directions. The left orbital tension was slightly higher. A fundus examination revealed the optic nerve head and retinal edema in the left eye . The right eye and the systemic examination were normal.
MRI confirmed the presence of a lacrimal gland lesion which was isointense to eye muscles on T1-weighted images and hyperintense on T2 weighted image. Coronal T1-weighted strengthened scanning images after gadolinium injection showed enhancement . Orbital metastasis increased the intra-orbital tension, resulting in optic disc and retinal edema. Optical coherence tomography (OCT) showed optic disc and retinal neuroepithelium edema.
The patient underwent lateral orbitotomy and lumpectomy after one week. The mass was exposed and revealed a moist, soft, gelatinous, and fleshy-pink tissue at the top of the left outside of the orbit. In the case operation, the orbital metastatic tumor was a large amount of gelatinous reddish tissue, and the texture of the tumor was fragile due to the lack of fibrous stroma.
Postoperative left exophthalmos and eye movement returned to normal. Upon ophthalmic examination post-operation, the visual acuity was 20/20 in her right eye and 20/25 in her left eye. The fundus examination after the operation revealed that the optic nerve head and retinal edema had disappeared in the left eye. A histopathological examination (HPE) of the specimen was reported as a metastatic GIST. The nuclei of the tumor cells were unusual upon digital microscopy imaging. Here, abnormal mitoses are indicated with arrows in the photograph. These results paralleled the expression of the liver tumors. The postoperative diagnosis was a left orbital metastasis of GIST. After leaving the hospital, the patient had no orbital oncology recurrence six months at follow-up.