Photodermatology Flashcards
What is photosensitivity
A group of skin disorders that result from exposure to normal levels of UV light exposure
Name some drugs that cause photosensitivity
Thiazide, amiodarone, chlorpromazine, doxycycline, quinine
What does skin type depend on
Eumelanin to photomelanin ratio
What is xeroderma pigmentosum
A group of autosomal recessive genetic disorders caused by a deficiency in the DNA repair mechanism in the skin
Clinical presentation of xeroderma pigmentosum
Severe photosensitivity
Accelerated photoaging
Ocular damage
Early formation of skin cancers
Management of xeroderma pigmentosum
Strict sun avoidance
What are porphyria’s
A group of photosensitivity disorders from a defect in the enzymes required to produce adequate amounts of haemoglobin
When does acute intermittent porphyria commonly present
In women around the age of 30
Clinical presentation of acute intermittent porphyria
Acute abdomen
Mood disturbance
Neurological symptoms: seizures
Enzyme that is deficient in acute intermittent porphyria
Porphobilinogen deaminase
What is the most common porphyria
Porphyria cutanea tarda
Who usually presents with porphyria cutanea tarda
Middle aged men
What is commonly associated with porphyria cutanea tarda
Liver disease: haemochromatosis, hepatitis, alcohol misuse
Enzyme deficient in porphyria cutanea tarda
Uroporphyrinogen decarboxylase
Clinical presentation of porphyria cutanea tarda
Blistering lesions on sun exposed sites that heal with scarring and are associated with hyperpigmentation
Investigations in porphyria cutanea tarda
Bloods: porphyrin studies
Woods lamp
Woods lamp investigation in porphyria cutanea tarda
Urine shines pink instead of blue
Inheritance seen in erythropoietic protoporphyria
Autosomal dominant
Who usually presents with erythropoietic protoporphyria
Children
Enzyme deficient in erythropoietic protoporphyria
Ferrochelatase
Typical presentation of erythropoietic protoporphyria
Child screaming when placed out in the sun
Diagnosis of erythropoietic protoporphyria
Elevation of red cell protoporphyrin
Management of erythropoietic protoporphyria
Visible light protection measures
