Case 1 – White Spots ( Fig. 24.1 ) What Is the Most Likely Diagnosis? This patient has a typical history for tinea versicolor. Scratching the affected areas elicited a fine, crumbly scale, further heightening the suspicion of tinea versicolor. What Test Would You Do? The potassium hydroxide (KOH) preparation is diagnostic, revealing numerous short hyphae and spores. How Would You Treat This Patient? Fluconazole was…

Fever and Rash Key Points 1. Characterize the rash to limit the differential diagnosis 2. Do laboratory tests based on the history and physical examination A wide spectrum of diseases can present with fever and rash, including infections, drug reactions (e.g., DRESS; Fig 23.1 ), collagen vascular diseases, and vasculitis. These causes are listed in Table 23.1 , according to the primary cutaneous lesions: macules and…

Categorization of mucous membrand disorders: 1. Erosions and ulcerations 2. White lesions Table 22.1 Mucous Membrane Disorders Etiology History Physical Examination Differential Diagnosis Laboratory Test Ulcers Aphthous stomatitis (common cause) Unknown Recurrent disease Sharply demarcated, round, yellowish erosions surrounded by erythema Herpes simplex Behçeťs syndrome Inflammatory bowel disease – Pemphigus and pemphigoid (uncommon causes) Autoimmune May have associated skin lesions Ragged erosions and ulcerations; intact blisters…

Key Points 1. Appearance alone is usually not sufficient to make the diagnosis 2. Therapy is often difficult or unsuccessful The physical appearance of the nail cannot be used reliably to make a diagnosis. Fungal Infection Key Points 1. Confirm the diagnosis with PAS stain, culture or KOH preparation 2. Cure requires oral therapy Definition Onychomycosis and tinea unguium are synonyms for infection of the nail…

Key Points 1. Diagnosis requires a detailed history 2. Diagnose pattern as patchy or diffuse 3. Determine whether hair loss is scarring or nonscarring Observe the pattern of hair loss and whether scarring is present. Alopecia Areata Key Points 1. Autoimmune disorder 2. Acute onset of well-circumscribed, oval patches of nonscarring alopecia 3. No cure Table 20.1 Alopecia Incidence (%) a History Physical Examination Scarring Pattern…

Key Points 1. Ulcers have many causes 2. Good wound care promotes healing 3. Cure requires resolution of the underlying etiology Definition An ulcer is an open sore that results from loss of the epidermis and part or all of the dermis ( Fig. 19.1 ). Ulcers have numerous causes ( Table 19.1 ). A detailed history and physical examination are often sufficient to establish a…

Key Points 1. Dermal induration presents with firm and thickened skin 2. Skin biopsy is often necessary for diagnosis 3. Diseases tend to run a natural course despite treatment intervention Granuloma Annulare Key Points 1. Self-limiting, asymptomatic condition with papules arranged in annular configuration 2. Commonly affects children and young adults 3. Occurs mostly on dorsal hands and feet Definition Granuloma annulare is an asymptomatic skin…

Key Points 1. Purpura (Latin purple) is extravasated blood outside blood vessels and therefore does not blanch 2. Distinguish palpable from nonpalpable purpura 3. Palpable purpura represents vasculitis 4. Always rule out infection first in a patient with purpura Purpura is purple and nonblanchable. Purpura is divided into two major categories: nonpalpable (macular) and palpable (papular). Nonpalpable purpura results from bleeding into the skin without inflammation…

Key Points 1. The distinctive morphology of the specialized erythemas is key to the diagnosis (e.g., erythema multiforme) 2. Specialized erythemas represent a reactive pattern to an underlying cause (e.g., erythema multiforme caused by herpes simplex infection) Table 16.1 Specialized Erythema Frequency (%) a Etiology History Physical Examination Differential Diagnosis Laboratory Test Erythema migrans < 0.1 Tick-borne spirochete ( Borrelia burgdorferi ) Constitutional symptoms accompany rash…

Key Points 1. Dermal inflammation often presents as localized erythema 2. Localized erythema is most commonly owing to infection (e.g., cellulitis or abscess) or inflammation (e.g., erythema nodosum) Table 15.1 Localized Erythema Frequency (%) a Etiology History Physical Examination Differential Diagnosis Laboratory Test Abscess and furuncle 0.4 Staphylococcus aureus (usually) – Red, tender, fluctuant mass Nodular acne Hidradenitis suppurativa Culture Cellulitis 0.1 Group A streptococci (usually)…

Key Points 1. Drug reactions and viral exanthems are the most common causes of a generalized erythema 2. Rule out infection first in a patient with generalized erythema 3. Correct diagnosis requires complete history, physical examination with attention to sites of skin involvement, skin biopsy consideration, and appropriate laboratory work-up Drug Eruptions Key Points 1. Appear suddenly and with symmetry 2. Antibiotics, especially penicillins and sulfonamides,…

Key Points 1. Examine for partial versus complete pigment loss and presence or absence of scale 2. A Wood’s light examination accentuates white spots, especially in fair-skinned individuals 3. Vitiligo is a common cause of depigmentation White spots should be examined for: 1. Partial versus complete pigment loss 2. Presence or absence of scale The degree of pigment loss can be assessed roughly with a Wood’s…

Key Points 1. Pustules represent collections of neutrophils 2. Rule out infection when you see pustules 3. Pustules can be sterile Acne Key Points 1. Acne is the most common dermatologic disease with negative psychosocial ramifications 2. Comedones are the hallmark of the disease 3. Treatment targets multifactorial causes of acne: androgens, follicular obstruction, and Propionibacterium acnes Table 12.1 Common Pustular Diseases Physical Examination Frequency (%)…

Key Points 1. Itching is usually prominent 2. Primary lesion is usually a papule 3. Skin biopsy when needed confirms clinical suspicion Insect Bite Reactions Key Points 1. Immediate hives after insult suggest the diagnosis 2. Develop only in people who are allergic 3. Insect stings, not insect bites, are a common cause of anaphylaxis Table 11.1 Papules Frequency (%) a Etiology History Physical Examination Differential…

Key Points 1. Blistering is an easily recognized primary lesion 2. Weeping and crusting suggest a blistering process 3. There are multiple causes of blistering Where blisters occur in the skin helps in making the diagnosis 1. Intraepidermally 2. Subepidermally The following diseases illustrate the pathogenetic mechanisms involved in blister formation at the different levels of the skin. Detachment of the horny layer by an epidermolytic…

Key Points 1. Scaling disorders have multiple causes – immunologic, infectious, and neoplastic 2. Borders are usually distinct, in contrast to eczema 3. Scaling (stratum corneum) is not crusting (dried fluids and blood) The papulosquamous disorders have diverse causes, as seen in Table 9.1 . The lesions, in addition to being scaly, are sharply demarcated. The latter feature helps to distinguish them from scaling lesions of…

Key Points 1. Appearance varies from blisters to scaling, lichenified plaques 2. Itching is prominent 3. Distribution can be localized or generalized Types of dermatitis: 1. Acute – vesicles 2. Subacute – juicy papules 3. Chronic – lichenification The hallmarks of dermatitis are marked pruritus, indistinct borders (except for contact dermatitis), and epidermal changes characterized by vesicles, juicy papules, or lichenification. Dermatitis may be localized or…