Altered mental status as a presentation of juvenile polyposis syndrome

•JPC exhibits multiple polyps in the GI tract, commonly presenting with hematochezia.•Protein losing enteropathy with hypoalbuminemia can occur in JPC, although not common.•Protein S loss from malabsorption, along with MHTFR leads to sinus thrombosis.•Refractory protein loss, malabsorption and hematochezia warrant subtotal colectomy.•Prompt anticoagulation and treatment of malabsorption leads to no neurological sequelae.

Juvenile polyposis coli (JPC) is a rare hereditary disorder in which patients have multiple polyps in the gastrointestinal tract and present most commonly with hematochezia. We describe a 4-year-old with intermittent rectal prolapse presenting with altered mental status and headaches. JPC was diagnosed by the presence of multiple, pedunculated, colonic polyps on colonoscopy; his altered mental status resulted from cerebral venous sinus thrombosis. Although JPC is known to be associated with a protein losing enteropathy (PLE), this usually manifests as merely hypoalbuminemia and protein losses without major clinical sequelae. We present a rare complication of cerebral venous sinus thrombosis which highlights altered mental status as a rare presentation of JPC. To our knowledge, this is the first case report in the literature linking JPC, decreased protein S activity, a single mutation in the methylenetetrahydrofolate reductase gene and cerebral thrombosis.