Seborrheic dermatitis

•  pathogenesis probably involves sebum production and Pityrosporum fungus
                  - seborrheic dermatitis is located at sites of increased sebaceous gland
                    density and activity
                  - Pityrosporum is a lipophilic yeast that thrives on the lipids in sebum
                  - antifungals active against Pityrosporum can improve seborrheic dermatitis
                  - the scaling and inflammation seen clinically in seborrheic dermatitis may
                    represent a host response to increased numbers of Pityrosporum on the skin
   
     

     

•  clinical features:
                  - Adults:
                              - dandruff (dandruff alone probably represents the most mild form of
                                          seborrheic dermatitis)
                              - ill-defined areas of erythema with greasy-appearing scale
                              - face: glabella, eyelids, eyebrows, nasolabial folds, nose,
                                mustache/beard, ears
                              - trunk: presternal, umbilicus

     

    

•  clinical features:
                  - Infants:
                              - cradle-cap: thick adherent greasy scale over the scalp
                              - seborrheic dermatitis in infancy may also present as dermatitis in the
                                diaper region

     

     

•  associated disorders: seborrheic dermatitis is seen more frequently in:
              - Parkinson’s disease and immobility due to other neurologic disorders
                    (e.g. stroke, head or spinal cord injury)
              - HIV infection