Chapter 052. Approach to the Patient with a Skin Disorder (Part 1)

Harrisons Internal Medicine Chapter 52. Approach to the Patient with a Skin DisorderAPPROACH TO THE PATIENT WITH A SKIN DISORDER: INTRODUCTION The challenge of examining the skin lies in distinguishing normal from abnormal, significant findings from trivial ones, and in integrating pertinent signs and symptoms into an appropriate differential diagnosis. The fact that the largest organ in the body is visible is both an advantage and a disadvantage to those who examine it. It is advantageous because no special instrumentation is necessary and because the skin can be biopsied with little morbidity. ...
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Chapter 052. Approach to the Patient with a Skin Disorder (Part 1) Chapter 052. Approach to the Patient with a Skin Disorder (Part 1) Harrisons Internal Medicine > Chapter 52. Approach to the Patient witha Skin Disorder APPROACH TO THE PATIENT WITH A SKIN DISORDER:INTRODUCTION The challenge of examining the skin lies in distinguishing normal fromabnormal, significant findings from trivial ones, and in integrating pertinent signsand symptoms into an appropriate differential diagnosis. The fact that the largestorgan in the body is visible is both an advantage and a disadvantage to those whoexamine it. It is advantageous because no special instrumentation is necessary andbecause the skin can be biopsied with little morbidity. However, the casualobserver can be misled by a variety of stimuli and overlook important, subtle signsof skin or systemic disease. For instance, the sometimes minor differences in colorand shape that distinguish a melanoma (Fig. 52-1) from a benign nevomelanocyticnevus (Fig. 52-2) can be difficult to recognize. To aid in the interpretation of skinlesions, a variety of descriptive terms have been developed to characterizecutaneous lesions (Tables 52-1, 52-2, and 52-3 as well as Fig. 52-3) and toformulate a differential diagnosis (Table 52-4). For instance, the finding of scalingpapules (present in patients with psoriasis or atopic dermatitis) places the patientin a different diagnostic category than would hemorrhagic papules, which mayindicate vasculitis or sepsis (Figs. 52-4 and 52-5, respectively). It is also importantto differentiate primary from secondary skin lesions. If the examiner focuses onlinear erosions overlying an area of erythema and scaling, he or she mayincorrectly assume that the erosion is the primary lesion and the redness and scaleare secondary, while the correct interpretation would be that the patient has apruritic eczematous dermatitis with erosions caused by scratching. Figure 52-1 Superficial spreading melanoma. This is the most common type ofmelanoma. Such lesions usually demonstrate asymmetry, border irregularity, colorvariegation (black, blue, brown, pink, and white), a diameter >6 mm, and a historyof change (e.g., an increase in size or development of associated symptoms such aspruritus or pain). Figure 52-2 Table 52-1 Description of Primary Skin Lesions Macule: A flat, colored lesion, 2 cm) flat lesion with a color different from thesurrounding skin. This differs from a macule only in size. Papule: A small, solid lesion, 5 cm in diameter. Plaque: A large (>1 cm), flat-topped, raised lesion; edges may either bedistinct (e.g., in psoriasis) or gradually blend with surrounding skin (e.g., ineczematous dermatitis). Vesicle: A small, fluid-filled lesion, 0.5 cm in diameter. Wheal: A raised, erythematous, edematous papule or plaque, usuallyrepresenting short-lived vasodilatation and vasopermeability. Telangiectasia: A dilated, superficial blood vessel.