A 63-year-old man presented with a 2-month history of progressive right-sided exophthalmos, painful ophthalmoplegia and fevers. As more features developed, he was diagnosed with giant cell arteritis, then Tolosa-Hunt syndrome, and transiently responded to corticosteroids. A bland cerebrospinal fluid and highly metabolically active brain (F)-fluoro-D-glucose-positron emission tomography suggested lymphoma. Biopsy of the mass showed sulphur granules with Gram-positive filamentous bacteria with -like colonies. cavernous sinus infections are rare and indolent. They often mimic non-infective causes including other inflammatory and infiltrative conditions, vascular and neoplastic causes, particularly lymphoma. Clinicians should consider infective cavernous sinus syndromes in people with a fluctuating painful ophthalmoplegia that responds poorly to corticosteroids. The term Tolosa-Hunt syndrome is problematic and should be retired or used only with reservation.

CaseWe report an unusual case of a 63 year old man who developed progressive right-sided exophthalmos, painful ophthalmoplegia, headaches and fevers with worsening depression over a two-month period, subsequently identified as an Actinomyces cavernous sinus (CS) infection. Preliminary diagnoses included giant cell arteritis then Tolosa-Hunt syndrome, with a transient response to steroids. Investigations showed a bland CSF and highly metabolically active brain FDG-PET suggesting lymphoma. Biopsy of the mass demonstrated gram-positive filamentous bacteria with Actinomyces-like colonies with sulphur granules. Actinomyces CS infections are rare. They often mimic non-infectious etiologies including other inflammatory and infiltrative conditions, vascular and neoplastic causes, particularly lymphoma.ConclusionClinicians should consider infective CS syndromes in fluctuating painful ophthalmoplegias with poor response to steroids. In our view, “Tolosa-Hunt” should not be used as a diagnosis but merely used as a descriptor for syndromes that resolve with corticosteroids in the absence of a more precise diagnosis.