Causes and available treatments for inflamed vermilion border / lip edge? (photos)

Inflamed vermilion border of top lip (see pictures). Long history of seborrheic dermatitis & rosacea on other parts of face (i.e., above top lip, T-zone, cheeks) treated with ketoconazole 2% lotion and corticosteroid lotion, but vermilion border has never been specifically treated/targeted. Curious of possible causes and any/all available treatments. Thanks.