What is photosensitivity?
Symptoms caused by the exposure of skin to the UV radiation from the sun
What is the Fitzpatrick scale?
Scale of skin types and what happens to them upon exposure to the sun (burn vs. tan)
What are the porphyrias?
Group of diseases caused by abnormal haem metabolism - genetic mutations cause enzyme blocks.
The ones we need to know:
Acute intermittent porphyria (acute attacks, no skin symptoms)
Porphyria cutanea tarda
Erythropoietic protoporphyria (both present as photosensitivity)
See OneNote for summaries
Questions of acute intermittent porphyria: https://www.valuemd.com/usmle-step-1-forum/1309-question-stem-5-porphyria-questions.html