Primary Conjunctival Embryonal Rhabdomyosarcoma in a 19-Year-Old Man: A Case Report

Abstract

Background: Primary conjunctival embryonal rhabdomyosarcoma is an exceptionally uncommon ocular surface malignancy that can resemble benign conjunctival lesions. This report describes its clinical, histopathological, immunohistochemical, radiological and staging features in a young adult. Presentation of Case: A 19-year-old man with no relevant medical or familial history presented with a rapidly progressive right ocular mass that had progressed over one month. Best-corrected visual acuity was 8/10 in the right eye and 10/10 in the left eye. The right eye showed a large vascularised polypoid mass measuring 28 x 18 x 16 mm, arising from the inferior conjunctival fornix and adjacent bulbar conjunctiva. The left eye was clinically normal. Subtotal excision revealed a malignant small round cell tumour with hyperchromatic nuclei, mitotic activity, myxoid and vascularised stroma, and multinucleated tumour cells. Immunohistochemistry showed strong desmin positivity, supporting embryonal RMS. Orbital MRI showed enhancing inferior conjunctival thickening contacting the inferior and medial rectus muscles without extraocular muscle invasion, deep orbital extension or intracranial involvement. Systemic staging showed no distant metastasis. Discussion: The tumour was classified as embryonal RMS with residual local disease after subtotal excision, corresponding clinically to Group III disease under the Intergroup Rhabdomyosarcoma Study framework. Management required urgent multidisciplinary oncologic referral for systemic chemotherapy and local-control planning. The main limitations were the absence of a broad immunohistochemical and molecular panel and incomplete long-term oncologic follow-up in the ophthalmology record. Conclusion: Rapidly enlarging conjunctival masses in young patients should prompt early biopsy, orbital imaging, systemic staging and urgent oncologic referral.