Purpose: Solitary fibrous tumor (SFT) is a rare tumor derived from mesenchymal cells and mainly occurs in the pleura. We report the first case of subconjunctival SFT in Japan.
Case: The patient was a 51-year-old woman. At the age of 50 years, she noticed a rice-grain-sized mass in the conjunctiva of her left eye, which gradually enlarged. Owing to discomfort during eye movement and blinking, she visited another hospital. She was referred to Kansai Medical University Hospital because a mass containing blood vessels was found in the inferior nasal bulbar conjunctiva and fornix in her left eye. Initial examination revealed a best-corrected visual acuity of 0.7 in the right eye and 1.0 in the left eye. Intraocular pressure was 21 mmHg in the right eye and 18 mmHg in the left eye. A 9.5 mm×6.0 mm, milky-white, irregularly shaped solid mass was observed on the nasal side of the conjunctiva of the left eye. She had a history of breast cancer. Therefore, resection of the subconjunctival tumor in her left eye was performed due to suspicious of metastatic subconjunctival tumor. Microscopic examination of the excised mass revealed a patternless pattern with no specific arrangement of spindle-shaped cells and intervening collagen fibers on hematoxylin-eosin (HE) staining. The excision margin was partially positive. Immunostaining with antibodies against CD34, vimentin, and signal transducer and activator of transcription 6 (STAT6) revealed positive findings. Immunostaining with antibodies against S-100, smooth muscle actin (SMA), AE1/3, and c-kit showed negative findings. Ki-67 index was 3%. Based on the abovementioned histopathological findings, the mass was diagnosed as SFT. At 12 months after the resection, the patient showed no local recurrence and had an uneventful course.
Conclusions: In the case of subconjunctival tumors, diagnosing SFT based only on clinical findings is particularly challenging, but a definitive diagnosis can be made based on histopathological findings, as in this case. Owing to the possibility of local recurrence or distant metastasis, long-term follow-up should be conducted subsequently.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 126: 183-188, 2022.