Variegate porphyria complicated by systemic AA amyloidosis: a case report
A 35-year-old Japanese woman was admitted to our hospital for the evaluation of bilateral arthropathy affecting the joints of her hands, feet, knees, ankles, shoulders and hips. She complained of pain in multiple joints, but swelling was not apparent. C-reactive protein was 4.0 mg/dL, but rheumatoid factor was negative. Radiographs did not disclose any loss or narrowing of the joint spaces. She did not have a family history of such arthropathy or of autoimmune disease, including rheumatoid arthritis. Two years later, blister formation after exposure to the sun and reddish urine were noted, and these symptoms showed repeated remission and exacerbation. At 40 years old, evaluation of the urinary excretion of porphyrin metabolites showed that daily ∂ aminolevulinic acid (ALA) excretion was 1.68 mg/dL (normal range: <0.5 mg/dL), while the daily excretion of porphobilinogen (PBG) was 1.42 mg (normal range: <0.8 mg) and coproporphyrin was 0.274 mg (normal range: <0.10 mg). Accordingly, VP was diagnosed. In addition to avoidance of sun exposure, administration of prednisolone (20 mg daily) was effective for her skin lesions and arthropathy, but symptoms recurred after tapering. She also noted that a low-dose contraceptive improved her symptoms. At the age of 45 years, her renal function declined with a serum creatinine of 3.4 mg/dL. In addition, she had nausea, vomiting, abdominal pain without rebound tenderness and clonic convulsions. After administration of phenobarbital, reddish urine appeared and muscular weakness progressed to atonic quadraparesis. Acute porphyria was diagnosed because of elevated urinary excretion of PBG to 51.296 mg daily (normal range: <0.8 mg) and coproporphyrinogen to 0.271 mg daily (normal range: <0.16 mg). Her symptoms subsided after plasma exchange plus high-dose glucose therapy. In addition, hematin therapy was effective for her porphyria after four months. However, hypertension became refractory and renal dysfunction progressed. At the age of 47 years, hemodialysis was started when her serum creatinine was 11.0 mg/dL and congestive heart failure had developed. At the age of 49 years, her gastrointestinal symptoms and skin lesions became worse. Gastroduodenoscopy and colonoscopy did not reveal any ulcerated lesions. However, she died of refractory thrombocytopenia and anemia due to bleeding from the gastrointestinal tract. Throughout the clinical course, C-reactive protein (CRP) remained positive, rheumatoid factor was negative, serum AA protein was over 20 µg/mL (normal range: <8.0 µg/mL) and radiographs did not show any joint deformities consistent with rheumatoid arthritis.