Photodermatology

Question 1

what is phototoxicity

Answer 1

chemically induced skin irritation, that doesnt involve the immune system

Question 2

what is the fitzpatrick scale

Answer 2

numerical classification schema for skin colour

Question 3

polymorphic light eruption

Answer 3

rash caused by sun exposure in people who have sensitivity to sunlight . small red raised bumps

Question 4

porphyria

Answer 4

Caused by abnormalities of enzymes involved in the biosynthesis of haem, resulting in overproduction of the intermediate compounds called ‘porphyrins.’

Cause sensitivity to sunlight

Accumulation detectable in the blood, urine and faeces, and are toxic to the nervous system and cause photosensitvity in the skin

Question 5

Porphyria Cutaena Tarda clinical features

Answer 5

Presents with a bullous eruption on exposure to sunlight (face and hands), the eruption heals with scarring. Fragile, hairy skin.

Question 6

what is Porphyria Cutaena Tarda associated with

Answer 6

associated with things that increase the production of porphyrins:

• alcohol and liver disease
• hepatitis C, iron overload and HIV can also precipitate the disease

Question 7

Porphyria Cutaena Tarda investigations

Answer 7

woods lamp

diagnosis is dependent on demonstration of increased levels of urinary uroporphyrin

urine is darker than usual

Question 8

Porphyria Cutaena Tarda management

Answer 8

underlying cause - alcohol, viral hep, oestrogens or haemochromatosis

Question 9

Porphyria Cutaena Tarda management aim

Answer 9

to treat underlying disease and relieve skin disease

Question 10

Erythropoietic Protoporphyria

Answer 10

deficiency of the enzyme ferrochelastase, which leads to accumulation of photoporphyrin

Question 11

Erythropoietic Protoporphyria CF

Answer 11

painful red blistering eruption that starts in childhood

first signs appear as painful or burning sensation of the skin after sun exposure

pitted linear scars left on hands and nose

Question 12

Erythropoietic Protoporphyria investigations

Answer 12

diagnosis is confirmed by decreased ferrochelatase and increased levels of protoporphyrin (RBC and stool)

fluorocytes - RBC

transaminases , Hb conc

Question 13

Erythropoietic Protoporphyria management

Answer 13

• 6 monthly LFT nd RBC porphyrin
• Visible light photoprotection measures
• UBV phototherapy (TL-01) can reduce sun sensitivity in some patients

Question 14

what chemicals can be used in sunscreen for photoprotection

Answer 14

titanium and zinc oxide as they reflect visible light

Question 15

what supplementation is recommended in those who strictly avoid sunlight

Answer 15

vitamin D

Question 16

Acute Intermittent Porphyria

Answer 16

genetic metabolic disorder affecting the production of heme . deficiency of PBG deaminase

Question 17

Acute Intermittent Porphyria what else to consider in differential

Answer 17

acute abdomen , guillan-barré syndrome , psychoses , mononeuritis multiplex

Question 18

symptoms and severity of acute intermittent photoporphyria

Answer 18

vary between patients, some patients will never experience any symptoms

Acute attacks present with neurovisceral symptoms e.g. neuropathy, epilepsy, psychiatric disorders, visceral (abdominal pain, vomiting, constipation, fever, tachycardia, hypertension). (Symptoms don’t actually affect the skin).

Question 19

does phototoxicity involve the immune system

Answer 19

no

Question 20

which drugs can cause a phototoxic reaction

Answer 20

• Trimethoprim, tetracyclines, NSAIDs, diuretics, vitamin A derivatives, anti-fungals etc.