Case Presentation: A 19 yo female presented to our hospital with the complaint of lower extremity weakness and paresthesias. She had a history of episodic abdominal pain with vomiting, headaches, and paresthesias. Prior evaluations for these symptoms had led to diagnoses of fibromyalgia, migraine headaches and cyclic vomiting with erosive esophagitis. She had experienced lower extremity weakness during prior episodes but it was mild and resolved over a period of days. On this occasion, her lower extremity weakness was to the degree that she could no longer stand or walk.
Physical exam revealed diffuse lower extremity weakness, diminished sensation to light touch in lower extremities and absent vibratory sensation in the right leg. Deep tendon reflexes were 2 + and symmetric in upper and lower extremities. Brain MRI showed high T2 signal involving the parietal lobes and surrounding the ventricles suggestive of transient edema from posterior reversible encephalopathy (PRES). MRIs of the cervical, thoracic and lumbar spine were normal. Urine studies were sent to evaluate for porphyrias given her history of both gastrointestinal and neurologic complaints. She was found to have elevated urinary coproporphyrins I and III, supporting a diagnosis of hereditary coproporphyria.
Discussion: Hereditary Coproporphyria (HCP) is an inherited condition characterized by episodes of neurovisceral symptoms, similar to other acute porphyrias. It is a relatively rare condition with an estimated prevalence of 2 to 5 per million population. The condition manifests more frequently in females, though the associated gene mutation occurs with the same frequency in males and females among families with HCP. The age of onset is typically after puberty and may be related to hormonal changes with menstrual cycles. Brain imaging in cases of acute porphyria can show findings similar to those seen in PRES.
Conclusions: This case highlights the importance of a thorough history, which can bring unexpected conditions to the forefront of a differential. Anchoring bias from previous diagnoses as well as Zebra retreat, can cause a delay in reaching the correct diagnosis and were threats in this case. Porphyrias are challenging to diagnose because they are rare and presenting symptoms can be non-specific. Prompt diagnosis of porphyria is needed as acute attacks can carry substantial morbidity and mortality.