[Paraganglioma of the cauda equina]

We report on a case of paraganglioma of the cauda equina in a 48-year-old man. These slow-growing, mostly benign and encapsulated intradural-extramedullar tumours are clinically characterized by lumbago, paraesthesia and motor deficits as well as occasionally by incontinence. Paragangliomas of the cauda equina show monomorphous (main) cells arranged in a typical cell cluster pattern, demonstrating a lobular architecture and a fine net of connective tissue formed by so-called sustentacular cells; some tumours show focal ganglionic differentiation. Because of their morphological similarity to the more common ependymomas, paragangliomas of the cauda equina are sometimes misdiagnosed so that their incidence is likely to be higher than previously estimated. Immunohistochemistry findings are positive for neuron-specific enolase, chromogranin and other neuronal markers as well as neuropeptides (main cells) and S-100 protein (sustentacular cells) while widely lacking reactivity for GFAP. Paragangliomas of the cauda equina represent a rare entity, of which only 80 cases have been described in the literature. Because they only occur sporadically, they are often not included in the differential diagnosis of mass lesions of the region of the cauda equina.