Bilateral symmetrical metastasis to all extraocular muscles from distant rhabdomyosarcoma.

INTRODUCTION: Rhabdomyosarcoma arising in the inguinal region has high potential of metastasis. The common sites for spread from inguinal region include regional lymph nodes, lungs, bone marrow and bone cortex. Orbit is an uncommon site for such metastasis. This case report describes a patient with inguinal rhabdomyosarcoma, which metastasized to both orbits to all the extraocular muscles. CASE REPORT: A 14-year-old male patient presented with inguinal mass involving the scrotum. The patient underwent high inguinal orchiectomy with hemiscrotectomy for the mass and histopathology revealed rhabdomyosarcoma. After 2 weeks of initial surgery the patient developed bilateral axial proptosis and radiological imaging revealed bilateral extraocular muscle thickening involving all the extraocular muscles. A biopsy of right superior rectus muscle confirmed rhabdomyosarcoma. COMMENT: Although rhabdomyosarcoma is the commonest primary orbital malignant mass developing in young patients, it is an uncommon metastasis. Metastasis from inguinal rhabdomyosarcoma to extraocular muscles bilaterally involving all the muscles has not been reported in the literature. The present report describes one such patient with favorable initial response to chemotherapy and muscle thickness reverting to normal. Metastasis from a distant site should be considered in differential diagnosis when evaluating a patient with bilateral enlargement of all extraocular muscles.