Upper-Eyelid Nodular Fasciitis: A Rare Benign Tumor Mimicking Schwannoma: First Case Report of Upper-Eyelid Nodular Faciitis

Abstract

Nodular fasciitis (NF) is a non-malignant tumor consisted of the rapidly growing myofibroblasts. The proliferation on histopathology is similar to malignant spindle cell tumors. NF is common in the trunk and extremities, however there are rare chances of periorbital involvement with only a few cases reported in the existing literature. In this case report a 22-year-old male presented with a six-month history of a painless, gradually enlarging subcutaneous nodule of the left upper eyelid, with no preceding history of facial injury, burns, surgery or trauma. The lesion was initially diagnosed clinically as a dermoid cyst on upper eye lid and excised under general anesthesia via a skin crease incision. The sample was sent to the laboratory to confirm the diagnosis. Histopathology of the lesion was reported as a well-circumscribed, nonencapsulated spindle cell proliferation. The cells are arranged in short fascicles within a myxoid-to-collagenous stroma, with extravasated erythrocytes, increasing the probability of schwannoma on histopathology. Immunohistochemistry showed SMA positivity with absence of SOX10 and S-100, confirming NF as a final diagnosis. This case highlights the importance of distinguishing NF from neurogenic tumors through careful immunohistochemical evaluation when clinical findings are unclear. Simple excision is a treatment of choice with a low recurrence on follow ups. Molecular testing for USP6 gene rearrangement can provide confirmation in diagnostically challenging cases. The diagnostic workflows should be revised and there is a dire need for broader integration of immunohistochemistry into routine practice.