Reactive Orbital Myositis as a First Manifestation of Renal Cell Carcinoma.

Introduction: Orbital myositis (OM) is an inflammatory condition of the extraocular muscles, often idiopathic but occasionally associated with systemic diseases or malignancies. Secondary OM due to metastatic disease is rare. We report a case of OM as the initial manifestation of metastatic renal cell carcinoma, emphasizing the need for comprehensive evaluation of atypical ocular presentations.

Case presentation: An 81-year-old male with a history of age-related macular degeneration presented with acute onset of pain and restricted movement in his left eye. Computed tomography imaging revealed an osteolytic lesion in the left sphenoid bone, causing reactive myositis. Further systemic evaluation identified a left renal mass with evidence of pulmonary and skeletal metastases. A core needle biopsy confirmed the diagnosis of metastatic renal cell carcinoma. Given the advanced disease stage, the patient was managed with palliative treatment. Despite medical interventions, he succumbed to the disease 6 months after symptom onset.

Conclusion: This case underscores the significance of considering malignancy in the differential diagnosis of OM, particularly in elderly patients with atypical ocular symptoms. Early recognition and systemic evaluation are crucial for timely diagnosis and management of underlying malignancies presenting with orbital involvement.