How does seborrheic dermatitis cause red face?

• Seborrheic dermatitis is a very common inflammatory reaction to the Malassezia (Pityrosporum ovale) yeast that thrives on seborrheic (oil- producing) skin • It presents as erythematous scaling patches on the scalp, hairline, eyebrows, eyelids, central face and nasolabial folds, or external auditory canals • In patients with darker skin it can be hypopigmented rather than erythematous • It can also affect the central chest and axillary folds • Seborrheic dermatitis is more common and severe in patients with HIV or neurologic disease (e.g. Parkinson’s disease or stroke)