ERYTHEMA ANNULARE CENTRIFUGUM
- Occurs at any age.
- May be related to: infections; parasites; drugs (antimalarials, penicillin, salicylates, cimetidine, amitriptyline); foods; cholestatic liver disease; or hyperthyroidism.
- Common on lower limbs but may occur on face, trunk and arms.
- Small inflammatory spot gradually spreads to form a ring. Central area flattens and clears.
- Generally no symptoms but may be slightly itchy.
- Skin scraping to exclude tinea or candida.
- Treat underlying cause or wait for spontaneous resolution.
- Topical steroid may reduce inflammation and itching.
PRIMARY CUTANEOUS T-CELL LYMPHOMA
- Lymphoma of the skin with no evidence of disease elsewhere in the body.
- May be cutaneous T-cell lymphoma (65 per cent) or cutaneous B-cell lymphoma.
- Uncommon skin condition. More common in men, rare in children.
- Cause unknown but possible persistent antigen leading to gene mutations.
- Patch stage: oval or annular dry, pink patches. Patches may slowly enlarge or disappear spontaneously. May be itchy and have atrophic appearance.
- Plaque stage: thickened, itchy patches.
- Tumour stage: plaque thickens into large nodules or tumours. May ulcerate.
- Skin biopsy to confirm diagnosis.
- CT or MRI scan in advanced cases to check if other organs involved.
- Depending on severity, use: topical steroids; phototherapy; topical nitrogen mustard; chemotherapy; radiotherapy; interferons; oral retinoids; or photopheresis.