Clinical Dermatology

Group Identification

Lesions assigned to the brown, blue, and black lesion group must be darker than the surrounding, normal skin. Colors appropriately considered for the lesions in this group include tan, brown, black, and blue. When the lesions are brown, particularly in a dark-skinned person, a careful search for underlying red hues should be undertaken. If redness is identified, lesions from groups 7 through 10 may also have to be considered.

Brown Patches and Plaques

The macules and patches of pityriasis (tinea) versicolor often assume a brown or brown-red color on areas of the body that receive little or no sunlight. This condition is covered more fully .

Hyperpigmentation frequently follows the presence of cuttaneous inflammation. This postinflammatory hyperpigmen­Lilion is particularly common in lichen planus, psoriasis, and many of the eczematous diseases. Postinflammatory hyperpigmentation gradually fades to normal skin color after a period of several months.

Chloasma, also known as melasma, is the term used for the patches of pigmentation that are found on the forehead similar prominences, and zygomatic areas of the face. It is mostly seen in women during pregnancy and in association with the use of birth control pills. Idiopathic cases, unassociated with hormonal changes, are occasionally seen in both men and women. The use of bleaches together with the use of sunscreens as described for lentigines may be of help if treatment is desired.

Brown Papules and Nodules

Skin lags are occasionally hyperpigmented. These lesions do not otherwise differ from their skin-colored counterparts. Flat warts are also occasionally hyperpigmented. Here, too, the prognosis and the therapy are no different than for skin-colored lesions.

Open cornedones are occluded hair follicles in which the keratin plug is visible within the follicular ostium as a black, partially depressed dot. Confirmation of a diagnosis is obtained by compression of the lesion, which results in extrusion of the plug. Similar black plugs sometimes occur at the outlet of epidermoid cysts.

Actinic keratoses sometimes present as small, brown, rough-surfaced papules. The color may be related to melanin granule retention in the multiple layers of the hyperkeratotic stratum corneum which histologically characterize this lesion. Brown actinic keratoses have no particular clinical significance.

Group Identification of White Lesion

Lesions must not only be white but must also be lighter than the surrounding skin to be classified as white lesions. For this reason, in very light skinned individuals it is sometimes difficult 10 decide whether a lesion should be classified with the skin-colored or the white lesions. When in doubt, the list of differential diagnoses should be made up from diseases in both groups.

Group Identification of Yellow Lesion

The yellow lesions are the easiest of the ten groups to recognize. The yellow color is distinctive except in some of the darkest skinned individuals, where it takes on a brownish lIne, All of the lesions in this group are smooth surfaced. If yellow lesion has a rough surface, it is undoubtedly due to the presence of serum in either the form of crust or the yellowing of scale. Crust indicates that there is underlying epithelial disruption, lesions with crust should be reclassified based on other lesional characteristics. Generally, crusted lesions are found in groups 1 (vesiculobullous lesions), group, (pustular lesions), or group 10 (eczematous lesions) . Yellow scale develops when the amount of serum present is too small to form as crust and instead simply discolors scale. This phenomenon is seen primarily in some ,clinic keratoses and diseases of group 10 (eczematous lesions).

Group Identification of Skin - Colored Lesions

The skin-colored papules and nodules are easy to identify provided that two general rules are kept in mind. First, a skin-colored lesion is the same color as the surrounding skin. Thus a dark-skinned person would have skin-colored lesions that are brown in color, whereas a light-skinned person would have skin-colored lesions that are nearly white in color. Second, a lesion that appears to be made up of nothing but scale (i.e., a lesion with no color or substance other than scale) is classified as a skin-colored lesion. This rule is particularly applicable in the case of actinic keratoses.

Group Identification of Red Macules, Papules, and Nodules

The red macules, papules, and nodules (group 7) are characterized by the presence of smooth­surfaced, nonscaling erythema. Since these characteristics are shared by the diseases of group 8 (the vascular reactions), some rules of thumb are necessary to help separate the two groups. First, the lesions of diseases in group 7 are generally monofonn in appearance (one looks just like the other), whereas those of group 8 vary in size and! or shape from one lesion to another. Second, cross-sectional profiles of lesions in group 7 are dome shaped, whereas the lesions of group 8 are generally flat topped. Third, solitary lesions, no matter what their morphology, are almost always found in group 7. Fourth, purpuric lesions are always assigned to group 8. Fifth, confluence of lesions, when present, favors assignment to group 8. One exception to this last rule occurs in the case of granuloma annulare, wherein individual papules may partially coalesce to form annular lesions.

In spite of these rules, there will be instances in which assignment to one of the two groups cannot be made with certainty. In such cases the list of differential diagnoses may need to be formed from diseases in both groups.

This entry was posted on Thursday, August 30th, 2007 at 10:58 am and is filed under Lesions. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.