Trade Secrets in Dermatology:

Diagnostic and Therapeutic

Paul Krusinski, MD

 

 

  1. Observation

    Having a visual aptitude is most important in Dermatology. To accurately describe what we see before us leads to the diagnosis. Often, searching for the correct word to describe the physical findings makes us look more intensely to discover more. Eyeglasses, contact lenses, a hand-held magnifying glass, viewing skin scrapings, or viewing a biopsy under a microscope are all on a continuum of visual observation.

  2. Morphology, Morphology, Morphology: The three most important words in clinical dermatology.
    1. Dried riverbed à xerotic dermatitis
    2. Sparing out of reach à neurotic excoriations
    3. Waist-band dermatitis à allergy to elastic in clothing
    4. Annular (moving) à urticarial
    5. Annular (fixed) à erythema multiforme
    6. "V"-shaped à factitial
    7. Rectilinear à external contact
  3. Diagnostic Techniques
    1. Diascopy
    2. Darier’s Sign
    3. Dermatographism
    4. Ice-cube Test à Cold urticaria
    5. Skin scraping (KOH) for scabies mites, eggs, or scabala
    6. Fountain pen burrow
    7. KOH for tinea
    8. Woods light
    9. Köebner phenomenon

      Psoriasis, lichen, planus, vitiligo, or warts

    10. Auspitz Sign

    Psoriasis

  4. Dermatologic Surgery
    1. Pre-operative thought à surgery à biopsy results
    2. You’re only as good as your pathologist who reads your slides
  5. Use and Abuse of Topical Steroids
    1. Topical corticosteroids are used to treat inflammation of the skin. Inflammation ranges widely from acute to chronic. The clinical picture varies widely in these forms, as do treatment requirements.
      1. Acute inflammation—redness and swelling. There may be blistering, oozing, and crust formation as well.
        1. In acute inflammation, generally a potent corticosteroid is needed because the inflammation is severe.

        2. If the areas are very widespread and severe, such as in widespread poison ivy dermatitis, systemic corticosteroids are necessary.

        3. The choice of topical steroid boils down to a choice of potency and vehicle. The specific discussion of vehicles is on the following page.
        4. For acute dermatitis, one usually chooses a thin lotion or cream vehicle because the rash is already moist and does not need the additional lubrication of a heavy ointment.
      2. Subacute—red, scaly patches which are sometimes somewhat thick, possibly with excoriations or tiny crusts.
        1. For subacute dermatitis, usually a medium cream vehicle is appropriate and comfortable. For mild patches, relatively weak corticosteroids will be adequate, but for severe red patches, the more potent products are necessary.
      3. Chronic inflammation—little redness if any, thickened, dry, and scaly. The most severe form is lichenification, which is very thick and has exaggerated skin fold lines.
        1. At the other end of the spectrum are chronic dermatoses. Since these are dry and scaly, a thick ointment or thick cream vehicle is appropriate. If the lesions are thick, a potent corticosteroid should be chosen that will penetrate adequately through the scale and thickened skin.
    2. Potency
      1. The potency of a topical steroid may be influenced by the vehicle.
        1. As a rule, the same material in an ointment is more potent than if it is in a cream or a thin lotion.
        2. The ointment occludes and hydrates the keratin layer, making it more permeable.
      2. In some instances, this difference is quite dramatic. If you examine the list of topical steroids ranked by potency on the following pages you can see a marked variation for Valisone.
        1. The lotion is in the weak group 6.
        2. The cream is in the somewhat stronger group 5.
        3. Ointment is in the more potent group 3.
      3. Vehicles can be manipulated to enhance penetration of the active ingredient, and thus enhance potency, which can equalize these differences in vehicles.
      4. Examining the potency chart, you can see that in group 2, there are three preparations of Topicort: in cream, gel, and ointment, indicating that their vehicles have been maximized to enhance penetration.

         

      5. Unfortunately, generic preparations of corticosteroids may be considerably weaker than their brand-name counterpart, which is related to the vehicle effect.
        1. Even though the active ingredient is present in the same concentration in the brand name and all generic forms, the potencies may vary considerably.
        2. These differences in potency are not measured and published in any way that guides us in selecting generics for our patients.
          1. One can only state that when you order a brand name steroid cream from, for example, group 2, you know you are getting the appropriate potency.
          2. If the patient is supplied with a generic equivalent of that product, it might be of equal potency, but more likely will be down lower on the potency chart and may be considerably weaker.
          3. In practice, if generic materials are not working, then it may be necessary to specify a brand name to be sure that adequate potency is being provided.
    1. Another factor affecting potency of topical corticosteroids is anatomic location.
    2. Thin-skinned and moist areas of the body absorb corticosteroids more readily than thick-skinned and dry areas.
      1. Using the forearm as a standard location, the sole of the foot absorbs only 14% as well.
      2. In contrast, the eyelid absorbs 13 times better, and the groin absorbs 42 times better (partially related to the moisture in the groin area, which makes the keratin layer more permeable.)
      3. Mild corticosteroids may work very well on the face and groin, whereas very potent ones will be needed for the palms and thick-skinned areas such as the back.
    3. Also enhancing potency is occlusion.
      1. This is achieved by applying the product and then covering it with plastic wrap such as Saran wrap, or plastic gloves, or plastic bags.
      2. This moist "tropical" environment makes the skin more permeable and can increase the effect of potency of the cortisone by 10 to 100 times.
      3. This technique is valuable for forcing penetration in thick plaques where topical corticosteroids alone may not be effective.
      4. It is messy and somewhat unpleasant to use and increases the risk of secondary bacterial infection if there are breaks in the skin.
      5. Now that ultra-potent corticosteroids are available (group 1 in the potency chart) the use of occlusion has declined greatly.
    1. Frequency of Application
      1. When topical corticosteroids were introduced 40 years ago, they were applied four times a day.
      2. The recommendation gradually decreased to three times a day, and then twice a day.
      3. Recent studies indicate that after a few days, the keratin layer becomes saturated with the steroid and thereafter acts as a reservoir, slowly releasing medication into the epidermis.
        1. At this point, once daily applications are probably adequate to keep maintaining the reservoir.
      4. From a practical standpoint, we usually recommend applying topical steroids twice a day initially, and then perhaps decreasing to once a day as the condition improves.
    2. Side Effects
      1. Topical corticosteroids are usually effective and safe, but side effects may occur.
      2. Systemic absorption is possible, but unusual.
        1. Ultra-potent cortisone creams may be measurably absorbed systemically if they are applied to a surface area as small as one square foot, especially if the skin is thin, but from a practical standpoint, much larger areas need to be covered before pharmacologically significant absorption occurs.
        2. For mid-potency steroids, almost the whole body needs to be covered to result in significant absorption.
        3. For very mild steroids, such as hydrocortisone, there is not significant absorption even from widespread use.
          1. An exception is infants and young children, whose skin is more permeable than that of adults, and whose surface-to-weight ratio is higher, resulting in higher blood levels.
            1. As a rule, we use milder steroids in infants, and those mild steroids tend to be adequate in them.
        4. Another exception is that raw, open skin absorbs more steroids than intact skin. As rashes heal, the absorption declines.
      3. Corticosteroids may cause skin side effects.
        1. One possibility is skin atrophy.
          1. Too potent a topical corticosteroid for too long may cause thinning of the skin. Underlying veins and structures become more visible, and the skin is usually shiny and pink.
          2. When the topical steroid is discontinued, atrophy usually reverses, unless there have been years of atrophy.
          3. Striae, which are permanent, may develop in susceptible areas such as the axillae and groin.

           

        2. Use of potent corticosteroids on the face, particularly in fair-skinned persons, may cause a rosacea-like eruption.
          1. Several weeks of use are required before this effect can occur, and it occurs in a relatively small portion of persons who use it.

          2. Because of this possible side effect, we try to use only mild cortisone creams on the face.
      4. Ocular side effects are also possible from topical corticosteroids.
        1. The eyelid skin is so thin that topical steroids can penetrate completely through them.
        2. In susceptible individuals, glaucoma and possibly cataracts may develop.
        3. Mild corticosteroids are usually effective on the eyelid and should not penetrate to a significant degree.

       

       

    3. Recommendations
      1. The list of topical corticosteroids available on the market is daunting.
      2. We recommend that the practitioner become familiar with a brand or two from the ultra-potent group 1, the potent group 2, the mid-level group 4 or 5, and then perhaps hydrocortisone 1% in group 7.
      3. Select the steroid vehicle based on anatomic location and dryness or moistness of the rash, and then select potency based on the severity of inflammation, anatomic location, and thickness of the plaque or scale.
      4. For severe rashes, use a very potent cortisone material, and for milder ones, select a milder preparation.
      5. For chronic diseases, such as atopic dermatitis, we may give our patients two or three different potencies and have them sue the very potent ones to bring eruptions under control, and then use medium or mild ones to maintain the benefit.
      6. We may also change the vehicle from summer to winter as the condition becomes drier or moister.

      7. Price is always a consideration, and correct instructions for frequency and thickness of application will maximize cost effectiveness.