Original papers
Porphyria cutanea tarda – analysis of main causes, clinical symptoms and laboratory abnormalities

Abstract
Introduction: Porphyria cutanea tarda (PCT) is one of the hepatic porphyrias, characterized by defective uroporphyrinogen III decarboxylase enzyme. Because of the rare incidence and often uncharacteristic symptoms, a proper diagnosis could be difficult. Aim: The aim of the study was to evaluate the main causes, symptoms and abnormal laboratory results among patients with PCT.
Material and methods: This retrospective study was based on the patients’ documentation data collected at the Department of Dermatology, Venereology and Allergology in Wroclaw between 1993 and 2007. Demographic data, type and location of skin lesions, coexisting diseases, exposure to hepatotoxic factors and laboratory findings were analysed.
Results: A total of 26 PCT patients were diagnosed, with male predominance (73.1% of cases) and a mean age of 51.5 ± 1.4 years. The median age of the PCT outbreak was 47.5 ± 11.8 years. A possible causative factor of liver damage was identified only in a half of patients: alcohol intake in 19.2%, hepatitis type C in 19.2%, professional exposure to hepatotoxic agents in 7.7%, and drugs in 3.8% of individuals. The following skin lesions were observed most commonly: blisters (65.4%), erosions (57.1%), scars (57.1%), hyperpigmentation (53.8%), crusts (19.2%), facial hypertrichosis (15.4%), and milia (7.7%). Skin changes were located mainly on the dorsal parts of hands (88.5%), on the face (50%), forearms (34.6%), back (26.9%), lower legs (19.2%), scalp (11.5%), and arms (7.7%). Increased skin fragility was reported by 42.3% and photosensitivity by 27% of patients. Blisters disappeared first during the treatment. The most frequent diseases coexisting with PCT were arterial hypertension (19.2%), arthropathy (15.4%) and diabetes mellitus (11.5%). Seventy-five percent of patients showed elevated serum activity of liver enzymes and 48% elevated iron serum concentration. Urine fluorescence under Wood’s light was observed in 95% of cases, but urine discolouration was only found in 40% of subjects. Conclusions: Our findings confirm that skin changes in PCT are located mainly on sun-exposed areas. Urine fluorescence under Wood’s light can be used as a simple screening test in PCT. Due to the possible coexistence of PCT and diabetes mellitus or haemochromatosis, glucose and iron metabolism should be precisely controlled in every patient with PCT.
Key words: porphyria cutanea tarda, porphyrins, clinical characteristics, liver damage.