Granular Cell Tumor

A patient was referred by an outside ophthalmologist for evaluation. The patient reported having headaches, double vision, and eye bulging for 3 months. Her exam was notable for restricted extraocular movements in her left eye on abduction and adduction. Her slit lamp exam was notable for proptosis of her left eye and mild increased resistance to retropulsion of left orbit. Prior to presentation, the patient underwent head and orbit MRI with and without contrast and was found to have a mass behind her left eye. Her laboratory workup, including thyroid studies, complete blood count, and vasculitis panel, were within normal limits. She was treated with prednisone and acetaminophen for the mass and the pain. Upon referral, she underwent an incisional biopsy of the left medial rectus muscle with the biopsy demonstrating histiocytes and fibrosis, leading to a presumptive diagnosis of idiopathic orbital inflammation. She continued treatment with methotrexate and prednisone with improvement of her proptosis and inflammation. A repeat MRI was obtained eight months later, demonstrating a T1 hypointense, enhancing mass with mixed T2 signal that had increased in size. The mass was completely resected. On histopathologic analysis, the mass was observed to be composed of sheets of cells with granular, eosinophilic cytoplasm. Immunohistochemical analysis demonstrated S100, NSE, and CD68 positivity, consistent with granular cell tumor.

Presentation Date: 03/14/2024

Issue Date: 03/29/2024