The Patient with Skin Disease: An Approach for Nondermatologists

   Nurses, nondermatology physicians, and other healthcare professionals frequently encounter patients with skin disease in their daily practice. In fact, of all patient visits to physicians for skin disease, the majority are to nondermatologists.¹

Unfortunately, nondermatology physicians lack the training and acumen compared to dermatologists with respect to the diagnosis and treatment of cutaneous disease^2-6; clearly, a need exists for either improvement in their skills or reliance on specialist consultation. To improve the quality of care rendered by nondermatologists, health professionals must become facile with several simple skills involved in the care of patients with cutaneous disorders, such as obtaining a dermatologic history, performing a dermatologic examination, and understanding and properly utilizing the dermatologic lexicon. This has the potential not only to enhance professional communication, but also to achieve more expeditious resolution of disease if proper diagnoses are made earlier.

Obtaining a Dermatologic History

   Many physicians have been taught in medical school that the most valuable information leading to an accurate diagnosis of a malady can be gleaned from taking a careful and thorough history. However, this is not always the case with respect to disease of the skin. In fact, the history obtained from patients with skin disease often can be quite misleading. Because the skin is uniquely situated- ie, much of it is visible to the naked eye- patients are often cognizant of skin lesions and have at least a vague idea of when the disorder began. Therefore, they are often apt to attribute some explanation, often erroneous, as to a cause. For example, ascribing a rash to a new laundry detergent or a recently ingested food is not unusual. Although laundry detergents can cause a contact dermatitis and people can develop urticaria and other lesions from food, this is uncommon. Similarly, patients often present complaining of a lesion that began after a spider or insect bite; in fact, the resultant rash is often from the self-treatment the patient applied. For this reason, clinicians should examine the skin carefully first, formulate a differential diagnosis, and subsequently obtain a focused history that limits the differential diagnosis further.

   When obtaining a dermatologic history, certain key elements are often very helpful. Demographic information frequently is of paramount importance because certain illnesses are more prevalent in one gender, certain ethnic groups, or in members of a specific age group. For example, systemic lupus erythematosus is more prevalent in young, African-American females; whereas, skin cancer is more common in elderly Caucasians.

   Inquiring about subjective cutaneous symptoms is often useful. Although many lesions are asymptomatic, patients may report pruritis, pain, throbbing, stinging, burning, or anesthesia. The pain of carbuncles, furuncles, and cellulitis may be described as throbbing, while an anesthetic hypopigmented patch is highly suggestive of leprosy.

   Determining whether the patient has ever experienced similar lesions is helpful and if this were the case, also learning the previous working diagnosis. The clinician also should ascertain if a previous biopsy or other dermatologic diagnostic procedure (eg, Tzanck smear, KOH, scabies, or molluscum preparations) was performed to lend more credence to a previous diagnosis. If a patient does not present with a definitive diagnosis, knowing the response to previous therapy can be helpful. For instance, should someone present with an intertriginous erythematous patch in the groin that did not respond to 3 weeks of topical antifungal therapy given by another clinician, the lesion is much less likely to be a dermatophyte or other fungus. Other possibilities become more likely, such as a steroid-responsive dermatitis (inverse psoriasis or eczema), erythrasma (a corynebacterium infection), and extramammary Paget's disease. Similarly, a patient might explain that whenever he/she develops this rash, he/she is helped dramatically by a topical corticosteroid or topical antifungal. This information also can be helpful.

   Because certain exogenous factors may induce skin disease, determining the patient's occupation and hobbies is important. Contact dermatitis is a common cause of dermatitis; other dermatoses may be caused by exposure to other agents (eg, Lyme's disease in patients who spend time outdoors in endemic areas, sporotrichosis in gardeners, and tularemia in animal skinners). Medications, either oral or parenteral, are another cause of cutaneous disease. Although anecdotal reports exist of medicines that, used chronically, cause drug eruptions, the offending agent is usually one recently started. Inquiring about the use of non-prescription agents is important because many over-the-counter medications can cause cutaneous drug eruptions.
Knowing the course of the skin lesion over time (both evolution and involution) provides additional clarification. A rapidly expanding annular lesion with central clearing is typical of erythema migrans, a skin lesion seen with Lyme disease; whereas, an annular lesion with central clearing of long-standing duration may be a dermatophyte or granuloma annulare.

   A review of systems, although time-consuming, may reveal evidence of constitutional symptoms indicative of acute illness or systemic disease. Other aspects of the history that can be useful include a sexual history, recent travel, living conditions, emotional status, pets, illicit drug use, and family history of skin diseases.

Performing a Dermatologic Examination

   One of the pitfalls in diagnosing cutaneous disease is not utilizing the information provided by detailed physical examination of the patient. To examine the patient properly, the clinician should evaluate not only the skin, but also the hair, nails, and mucous membranes. The room should be well-lit, with either natural light or a "daylight" type of lamp. If possible, the patient should be gowned and examined completely and systematically. The entire skin should be examined.

   Initially, before any individual lesion is examined, the observer should make an assessment of the entire patient, what is termed a "low power scan," to assess for acute illness as well as the distribution of lesions. Skin disease can be classified as being isolated (localized), regional, or generalized. Observing the patterns of distribution rather than solely focusing on individual skin lesions is beneficial to diagnosis. Certain disorders have a predilection for certain parts of the body and others have a characteristic distribution. Pretibial involvement is common in pyoderma gangrenosum, erythema nodosum, necrobiosis lipoidica diabeticorum, or pretibial myxedema, while popliteal fossa involvement is common in atopic dermatitis. Similarly, several disorders can cause vesicles, but when these vesicles are seen in a dermatomal distribution, the clinical diagnosis of herpes zoster becomes apparent. Other distributions that may provide important clues include acral versus central, covered versus exposed, extensor versus flexor, intertriginous, and mucosal.

   After examination from a distance (the generalized examination), the clinician should perform a lesional examination to determine both the type and arrangement (eg, linear, grouped, annular, targetoid, zosteriform, angular, geographic, reticulated, and serpiginous) of the lesion. Linear vesicles might indicate contact dermatitis; whereas, grouped vesicles on an erythematous base might be slightly more suggestive of cutaneous herpes simplex. Twisting, winding, serpiginous, linear lesions strongly suggest cutaneous larva migrans from hookworm infection.

Types of Skin Lesions

   Familiarity with the dermatologic lexicon is important to enhancing communication between healthcare professionals. Furthermore, knowledge of basic skin lesions is essential to generating a differential diagnosis. Skin lesions can be divided into primary skin lesions, the essential element upon which a diagnosis is made (see Table 1), and secondary lesions, which occur later (see Table 2).

   Primary skin lesions. A macule is a small, circumscribed, flat lesion that is different in color from the surrounding skin. The difference in color between the macule and the surrounding skin may be due to either increased or decreased melanin (hyperpigmentation, hypopigmentation, or depigmentation) (see Figure 1); dilatation of capillaries, leading to redness or erythema; vascular abnormalities causing telangiectasia; or purpura from extravasated red blood cells. Large macules (> 0.5 cm to 1 cm) are called patches.

   A small, solid, elevated lesion is called a papule. Papules may be caused by abnormalities of either the epidermis (the outermost layer of the skin) or the dermis (the layer below the epidermis). Papules may be flat, conical, verrucous, domed, or umbilicated. They may be red (as seen in psoriasis), skin-colored (as in sebaceous hyperplasia), purple (as in lichen planus), white (as in milia), yellow (as in xanthoma), brown (as in seborrheic keratosis), or black (as in melanoma) (see Figure 2). A nodule is a palpable, discrete, solid lesion (see Figure 3). The depth of this lesion differentiates a nodule from a papule. A plaque is a broad papule (> 1 cm) (see Figure 4) and may comprise several coalescing papules.

   Lesions may be fluid-filled. A vesicle is a fluid-containing lesion < 0.5 cm to 1 cm (see Figure 5); larger fluid-filled lesions are called bullae (see Figure 6). Vesicles and bullae are caused by cleavage at various levels of the skin; they may occur within the epidermis or at the dermal-epidermal junction. Determining the plane of cleavage can be helpful in distinguishing among certain disorders. Often, a skin biopsy with immunofluorescence is a useful diagnostic tool.

   Small, circumscribed elevations of the skin containing pus are pustules (see Figure 7). The purulent exudate contains white blood cells and may either contain microorganisms (as in folliculitis) or be sterile (as in pustular psoriasis). The purulent exudate is easily accessible and should be sent for Gram's stain and culture.

   Wheals (hives) are evanescent, edematous, flat-topped papules or plaques. They are usually white or pink and almost always pruritic. They may develop over a matter of minutes and generally disappear over a matter of hours.

   Secondary skin lesions. Secondary lesions may be seen either as part of the natural history of the disorder (such as scales in psoriasis and fissures in eczema) or from the actions of the patient (excoriations or lichenification from scratching).

   Masses of keratin form scales. The skin undergoes a constant process of desquamation. When this process is pathologically accelerated or interrupted, scales or desquamated areas may form. Large areas of desquamation may be seen in exfoliative dermatitis, after certain infections, and in toxic epidermal necrolysis.

   Fissures are linear cleavages through the epidermis, occasionally extending to the dermis. Fissures may be single or multiple, vary in length, and be painful. The pain may be exacerbated by movement if the fissures are opened more, become deeper, or new ones form.

   Crusts may be formed as serum, blood, or exudate dries on the skin surface. The color of the crust may offer some clues as to its etiology. Yellow crusts are formed from serum, yellow-green crusts are formed from purulent exudate, and dark red or brown crusts are formed from blood. Impetigo, a superficial skin infection from Staphylococcus aureus or Streptococcus is classically associated with honey-colored crusts.

   Patients with pruritus or with neuropsychiatric disorders frequently scratch and pick at their skin. Excoriations (linear or punctate excavations of the epidermis) arise from mechanical means such as scratching and often are seen in pruritic disorders such as scabies and atopic dermatitis. Repeated scratching can lead to thickening of the epidermis, hyperpigmentation, and accentuation of the lines of the skin, termed lichenification.

   Loss of portions of the epidermis lead to erosion (denuded skin), while excavations through the epidermis and extending into the dermis are termed ulcers. Ulcers can extend deep into the subcutaneous tissue, as can be seen in decubitus ulcers or basal cell cancers. Other secondary changes are atrophy (or thinning of the skin) and scarring.

Rationale for Developing a Dermatologic Lexicon

   As was mentioned previously, understanding and becoming facile at describing skin lesions is important. First, the lexicon provides a standardized language by which healthcare professionals can communicate with each other. Second, it provides the basis for more complex systems to rate or score the severity of skin disease. The importance of the latter has increased in response to the increased need for objective outcomes. Quite simply, one cannot measure outcomes without a standardized scoring system- most scoring systems utilize the basic dermatologic lexicon as their core.

   Third, clinicians should use the descriptive terms to develop a differential diagnosis. A red patch with scale could be several different diagnoses such as seborrheic dermatitis, squamous cell carcinoma in situ, contact dermatitis, tinea corporis (eg, pedis, mannum), fixed sporotrichosis, and a superficial gyrate erythema, among many possibilities. When the description is expanded to a red patch with scale in the groin, the differential diagnosis is limited somewhat, and when historical information (eg, patient's age, how the rash began, and what treatments were applied) is added, the differential diagnosis becomes even more restricted. If a red scaling patch in the groin of 2 weeks' duration was found in a 1-year-old child whose mother had been applying cream X, the differential diagnosis may be restricted to a yeast infection due to Candida albicans, a fungal infection, such as tinea cruris, or a contact dermatitis.

Dermatologic Testing

   Once a differential diagnosis has been generated, further testing often can lead to a more exact diagnosis. In the above example, differentiating a fungal or yeast infection from a contact dermatitis is important because the treatment for each differs. In the case described, a simple diagnostic test (potassium hydroxide preparation) can be used to detect fungal organisms. Simple bedside or office techniques can be utilized to make an exact diagnosis after a differential diagnoses has been generated (see Table 3). The practitioner can become more proficient in these tests (and therefore increase the tests' reliability) by seizing the opportunity to perform these tests when they are indicated.

   Potassium hydroxide preparation. This test is used to detect the presence of fungal or yeast organisms. It can determine if a hypopigmented or hyperpigmented patch is caused by tinea versicolor, if pustules are caused by a candidal infection, or if a scaly rash is due to a superficial dermatophyte infection. In this test, the material to be tested (ie, scale, subungal debris, hair, or pustule roof) is placed on a slide and a drop of potassium hydroxide (KOH, 10%) is added. Heat is gently applied or a chemical (DMSO) is added to the KOH to facilitate disruption of the cells and enable observation of the organisms. Viewed under a microscope, hyphae and spores (for dermatophytes), short hyphae and abundant spores (also known as "spaghetti and meatballs" for the yeast Pityrosporum ovale that causes tinea versicolor), or the nonseptated pseudohyphae of C. albicans can be observed.

   Tzanck preparation. This test is used to detect whether members of the herpes family of viruses are responsible for skin lesions, including cold sores (typically caused by herpes simplex I virus), genital herpes (usually caused by herpes simplex II virus), and chicken pox or shingles (caused by varicella- zoster virus). However, Tzanck will not distinguish among them. Typically, specimens from the floor of a blister will be placed on a slide along with a drop of Wright-Giemsa stain (although any stain that stains nuclei can be substituted, such as crystal violet). Viewed under a microscope, the presence of multinucleated keratinocytes (or giant cells) is diagnostic, although swollen and ballooned cells also may be observed.

   Molluscum preparation. The pox virus, molluscum contagiosum, typically causes an eruption of skin-colored umbilicated papules that may be localized and is often sexually transmitted in adults, or widespread, as sometimes occurs in children or the immunosuppressed. Although the classic lesions are easily recognized, in immunocompromised hosts, confirming the diagnosis is important because other life-threatening infections such as cryptococcosis or histoplasmosis may have similar skin lesions. In this test, the contents of the umbilicated papules are squeezed onto a slide and crushed between two slides. A drop of a nuclear stain (such as Wright-Giemsa) is applied. Viewed under a microscope, homoegeneous bodies termed molluscum bodies (or Henderson-Patterson bodies) confirm the diagnosis.

   Scabies preparation. The female itch mite, Sarcoptes scabeii, is the cause of the pruritic eruption, scabies. Characterized by excoriated red papules, pustules, and linear or serpiginous thin elevations that represent burrows, it can be readily diagnosed by the scabies preparation. Mineral oil or KOH solution (to make the scalpel sticky and adherent for the debris to be scraped) is applied to a scalpel and the stratum corneum is scraped off and placed on a slide. Viewed under a microscope, the presence of a mite, its feces (scybala), or eggs are diagnostic for a scabies infestation. The KOH solution helps dissolve the keratin and may facilitate identifying the mites.

   Wood's lamp examination. The Wood's lamp is a UVA light (365 nm or black light) used to detect several infectious organisms (eg, Microsporum species) that cause a minority of tinea capitis infections (green fluoresecence), erythrasma (a condition caused by a corynebacterium infection) that fluoresces pink, and Pseudomonas that fluoresces green. The Wood's lamp also can detect pigmentary abnormalities where the depigmented patches of vitiligo are more apparent and dermal pigmentation is less apparent. In this examination, the lights are dimmed and the Wood's lamp is shined on affected skin.

   The above tests can be performed and analyzed in a few minutes. They render an accurate diagnosis and can lead to the administration of appropriate therapy. Other tests, such as the skin biopsies, skin culturing, and laboratory testing are simple procedures that can be performed at the bedside or within the context of an outpatient visit, but the results are not immediately available to the clinician.

Conclusion

   To the uninitiated, the task of deciphering skin disease is extremely daunting. With a proper approach, clinicians can utilize the information provided by the patient to achieve maximum benefit for that particular patient. However, even the most astute clinicians often are unable to narrow the differential diagnosis to a single entity. In these cases, referral to specialists or performing dermatologic procedures is often necessary. Communication between nondermatologists and either dermatologists or other nondermatologists can be greatly enhanced by familiarity with the dermatologic lexicon. If these skills are used, the potential for early diagnosis and effective therapy may be achieved.

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