Causes of erythema nodosum (EN)

Bacterial infections: Streptococcus, Yersinia, Salmonella, Campylobacter, Chlamydia, Mycoplasma
Mycobacterial infection: TB, leprosy
Viral infection: Infectious mononucleosis, hepatitis B, herpes simplex
Other infection: Tinea, toxoplasma
Drugs: Sulfa drugs, OCP, potassium iodine agents
Malignant disease: Malignant lymphoma (Hodgkin's disease etc.), leukaemia
Inflammatory bowel disease: UC, Crohn's disease
Others: Sarcoidosis, Behcet's disease, reactive arthritis (Reiter's syndrome), pregnancy

Shimizu's dermatology 2nd Edition; page:385 and table 18.3
Rapid review of clinical medicine for MRCP part 2 by Sanjay Sharma (question no: 401)
Dermatology made easy 1st Edition; pages:571 & 576

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