We report a case of idiopathic hypertrophic cranial pachymeningitis (IHCP) associated with an orbital pseudotumor and granulocytic thyroiditis of unknown origin. The patient suffered from progressive and finally complete loss of visual acuity, as well as from multiple cranial nerve dysfunctions. Medical treatment and radiation therapy were not beneficial. As reported in the literature, the CT and MRI findings of IHCP were non-specific; thus, diagnosis had to be made by exclusion and open biopsy was required. An inflammatory pseudotumor of the orbit is rarely found in patients with IHCP. Thyroiditis has not yet been reported in the context of IHCP. The patient also suffered from anosmia, which is an unusual feature of IHCP.