RESUMO
The porphyrias are a group of metabolic disorders resulting from an innate abnormality in haem biosynthesis, and the clinical settings of which vary according to the genetic enzyme abnormality in question. These are genetic disorders with autosomal dominant or recessive inheritance of varying penetrance, and whose clinical expression differs according to the preferential location of haem precursors. Different classifications have been proposed according to genetic inheritance, the enzyme anomaly at issue, and clinical expression. The clinical classification distinguishes between acute porphyria (acute intermittent porphyria, porphyria variegata, hereditary coproporphyria), bullous cutaneous porphyrias (porphyria cutanea tarda, porphyria variegata and hereditary coproporphyria), painful photosensitive acute cutaneous porphyrias (erythropoietic protoporphyria and X-linked dominant protoporphyria), and rare recessive porphyrias (congenital erythropoietic porphyria, Doss porphyria, hepatoerythropoietic porphyria and harderoporphyria). Treatment depends on the clinical expression of the disorder.
Assuntos
Porfirias , Dermatopatias Metabólicas , Biópsia , Coproporfiria Hereditária/diagnóstico , Coproporfiria Hereditária/genética , Coproporfiria Hereditária/terapia , Diagnóstico Diferencial , Heme/biossíntese , Humanos , Transtornos de Fotossensibilidade/complicações , Transtornos de Fotossensibilidade/diagnóstico , Transtornos de Fotossensibilidade/terapia , Porfiria Cutânea Tardia/diagnóstico , Porfiria Cutânea Tardia/genética , Porfiria Cutânea Tardia/terapia , Porfiria Eritropoética/diagnóstico , Porfiria Eritropoética/genética , Porfiria Eritropoética/terapia , Porfirias/classificação , Porfirias/diagnóstico , Porfirias/genética , Porfirias/terapia , Protoporfiria Eritropoética/diagnóstico , Protoporfiria Eritropoética/genética , Protoporfiria Eritropoética/terapia , Pele/patologia , Dermatopatias Metabólicas/classificação , Dermatopatias Metabólicas/diagnóstico , Dermatopatias Metabólicas/genética , Dermatopatias Metabólicas/terapiaRESUMO
Extracellular deposition of altered autologous protein (amyloid protein) within the dermis is the hallmark of cutaneous amyloidoses and systemic amyloidoses with cutaneous involvement. Amyloidoses may be acquired or hereditary in nature and subclassification differentiates between primary amyloidosis (no obvious predisposing disease) and secondary amyloidosis (specific underlying disease). More than 26 different proteins and peptides have been identified as amyloid precursors and these proteins are used to subclassify this heterogeneous group of diseases. The amyloid proteins show an anti-parallel beta-sheet conformation and form non-branching linear filaments of variable lengths and diameters of approximately 7.5 to 10 nm. However, the exact etiopathogenesis of amyloid formation still remains unclear. Depending on histoanatomical distribution and amount, amyloid may cause progressive and life-threatening organ dysfunction. Clinical presentation, histology, electron microscopy, and biochemical-immunological differentiation represent decisive tools for an accurate diagnosis.
