Paraneoplastic orbital myositis as a first manifestation of renal cell carcinoma.

Paraneoplastic syndromes (PNSs) are remote effects of the primary tumor on tissues and organs, not related to direct invasion or metastasis. Ophthalmological involvement has been reported in 0.01-0.1% cases of PNSs. It may present as retinopathy, optic neuritis, myasthenia-like syndromes, or orbital myositis (OM), among others. An 89-year-old male with bilateral ocular pain and chemosis, was given an initial diagnosis of bilateral acute conjunctivitis. After 5 days, the patient presented worsening of the pain and bilateral complete ophthalmoplegia. Cranial CT scan showed diffuse bilateral thickening of the four rectus muscles. Inflammatory markers, thyroid hormones, and thyroid antibodies were normal. An abdominal ultrasound test was performed, observing a mass in the right kidney. After confirmation of the lesion with a CT scan, the radiological characteristics of the lesion were highly suggestive of renal cell carcinoma. Treatment with intravenous corticosteroids was ensued with complete resolution of all ophthalmological symptoms. Paraneoplastic orbital panmyositis was first described in 1994. Since then it has been reported scarcely, remaining an extremely rare entity. To our knowledge, this is the first report of its association with renal cell carcinoma. In the absence of inflammatory or dysthyroid blood markers, bilateral orbital panmyositis warrants further investigation for a possible underlying oncological pathology.