Adult and pediatric orbital rhabdomyosarcoma: comparison of characteristics and outcomes.

Introduction: Rhabdomyosarcoma (RMS) is a common pediatric orbital malignancy but is extremely rare in adults. This study assesses clinical and radiographic features, management, and outcomes in adult orbital RMS patients with comparison to pediatric patients.

Methods: A retrospective chart review from 2000-2023 at Bascom Palmer Eye Institute was conducted evaluating patients aged 0 to 100-years-old with biopsy-confirmed orbital RMS. Medical records were reviewed for demographics, clinical features, imaging, histopathology, management, and outcomes. Statistical analysis was conducted with Mann-U Whitney and chi-squared testing.

Results: Twenty-four patients were included, 15 children (mean age 6.4 ± 4.4 years) and 9 adults (35.7 ± 12.4 years). Patients in both groups presented with eyelid edema followed by proptosis with similar symptom duration (p = 0.31). Lesions were frequently located medially and inferiorly in both groups. At presentation, adults had significantly more metastatic disease in addition to bone, extraocular muscle, intracranial, and parameningeal involvement. The most common pediatric RMS subtype was embryonal (80%), whereas most adults were alveolar (77.8%, p = 0.001). Treatment in both groups frequently included chemoradiation. Both groups demonstrated similar local recurrence (p = 0.72), overall survival (p = 0.86), and ophthalmologic sequelae (p = 0.45), although pediatric follow-up duration was notably longer.

Conclusions: To our knowledge, this study is the largest report of adult orbital RMS from a single institution, highlights key comparisons in features and outcomes between adult and pediatric orbital RMS, and provides an updated literature review. While pediatric and adult orbital RMS clinical presentations are similar, adult disease more often demonstrates aggressive features, including alveolar subtype, local structure involvement, and lower disease-free survival.