Harrisons Principles of Internal Medicine Self-Assessment and Board Review 18th Ed.

SECTION XII. Dermatology

ANSWERS

XII-1.  The answer is D. (Chap. 51) Rashes and skin lesions are the most common reasons for visits to primary care physicians. Accurately characterizing a skin lesion is important for determining the underlying cause of the disease. Four basic features that are important when describing a skin lesion are the distribution, types of primary and secondary lesions, shape, and arrangement of lesions. The primary description of a skin lesion takes into account size, whether the lesion is raised or flat, and whether the lesion is fluid filled. Raised lesions can be papules, nodules, tumors, or plaques. A plaque is a raised lesion with a flat top that measures more than 1 cm in diameter. The edges may be distinct or gradually blend in with the surrounding skin. Papules, nodules, and tumors are similar raised solid lesions of the skin. These lesions differ only by size, with papules being smaller than 0.5 cm, nodules measuring 0.5–5.0 cm, and tumors measuring more than 5 cm. Macules and patches are not raised and also differ only by size, with macules being less than 2 cm and patches being greater than 2 cm. Vesicles are small (<0.5 cm) fluid-filled lesions, and pustules are vesicles containing leukocytes. Larger fluid-filled lesions are called bullae. A secondary description of a skin lesion takes into account features of the lesion. An excess accumulation of stratum corneum on a skin lesion is called a scale. Thus, this patient would be characterized as having a plaque with a scale. Other secondary descriptors include lichenification, which refers to a distinctive thickening of the skin that accentuates skinfold markings, and crusting, which refers to dried body fluids. In addition, the lesion may have erosions, ulceration, excoriation, atrophy, or scarring.

XII-2.  The answer is D. (Chap. 51) Characteristic terms are used in dermatology to describe a skin lesion. Nummular lesions are coin shaped and are closely related to annular lesions, which are ring shaped. A polycyclic eruption consists of a configuration of skin lesions that coalesce to form a ring or incomplete rings. Herpetiform lesions are grouped in a fashion that is seen in herpes simplex virus infection, whereas morbilliform lesions are generalized macules or papules that are similar to those seen in a measles eruption. Lichenoid rashes are violaceous lesions that resemble those seen in lichen planus.

XII-3.  The answer is D. (Chap. 52) These lesions are typical examples of childhood atopic dermatitis, the cutaneous expression of the atopic state. Over 75% of patients present by 5 years of age, and a similar proportion has concomitant asthma and/or allergic rhinitis. There is a strong genetic predisposition. Over 80% of children whose parents both have atopic dermatitis will have similar skin findings; the prevalence is approximately 50% when one parent is affected. In addition to the antecubital fossae, the face, neck, and other extensor surfaces are commonly affected. The typical course involves exacerbations and remissions. In the adult form, the disease is often localized lichen simplex chronicus or hand eczema. Treatment of atopic dermatitis involves adequate moisturizing, topical anti-inflammatories, and avoidance of secondary bacterial infection. Topical tacrolimus and pimecrolimus are approved as therapy. They do not cause some of the complications of topical corticosteroids, but recent reports have raised the concern of a potentially increased risk of lymphoma. Children with atopic dermatitis may have spontaneous resolution, but about 40% of children with symptoms will have dermatitis as adults. Interestingly, for unknown reasons the worldwide prevalence of atopic dermatitis is increasing.

XII-4.  The answer is E. (Chap. 52) All patients with psoriasis should be advised to avoid excessive drying of the skin and maintain hydration. Secondary bacterial infection should be suspected with local worsening and treated appropriately. Topical glucocorticoids often cause skin atrophy and lose effectiveness over time. Topical vitamin D analogues and retinoids have effectively replaced topical coal tar, salicylic acid, and anthralin as local adjunctive therapies. UV-A (with psoralen) and/or UV-B light is an effective therapy for widespread psoriasis in many cases. These therapies may be associated with an increased risk of skin cancer, particularly in patients who are immunocompromised. Methotrexate is often effective in patients with psoriatic arthritis (up to 30% of patients with psoriasis). Cyclosporine and other modulators of T-cell mediated immunity are effective in psoriasis. Alefacept is an intramuscular biologic that is anti-CD2 and is indicated in psoriasis. It may cause lymphopenia, increased risk of infection, or secondary malignancy. Infliximab, etanercept, and adalimumab are anti-TNF biologics indicated for use in psoriasis arthritis (etanercept is indicated for psoriasis). They are associated with an increased risk of serious systemic infection, neurologic events (progressive multifocal leukoencephalopathy), and hypersensitivity reactions. Oral glucocorticoids should not be used for the treatment of psoriasis due to the potential for developing life-threatening pustular psoriasis when the therapy is discontinued.

XII-5.  The answer is E. (Chap. 54) Bullous pemphigoid is an autoimmune skin disease associated with the development of tense vesicles and bullae on erythematous bases. The disease is more common in elderly individuals and typically begins as urticarial plaques that are located on the lower abdomen, groin, and flexor surfaces of the extremities. These lesions often evolve to tense bullae on erythematous or normal-appearing skin. Oral mucosal lesions can occur, and pruritus is variable from none to severe. The blisters often rupture with secondary erosions and crusting. Without secondary trauma, these lesions will heal without scarring. Biopsy of early lesions shows subepidermal blisters with a variable inflammatory infiltrate. Lesions on an erythematous base demonstrate eosinophilic infiltrates, whereas lesions on normal skin have minimal perivascular infiltrate only. Direct immunofluorescence shows linear deposits of IgG and C3 along the epidermal basement membranes. In about 70% of individuals, autoantibodies can be found that bind to the epidermal basement membrane. The disease tends to be chronic with relapses and remissions over a period of months to years. The treatment of choice is systemic glucocorticoids at doses of prednisone equivalent to 0.75–1 mg/kg daily.

XII-6.  The answer is D. (Chap. 54) Dermatitis herpetiformis (DH) is an immunologic skin disorder characterized by severe pruritus with skin lesions symmetrically distributed along the extensor surfaces, buttocks, back, scalp, and posterior neck. The lesions of DH may be papular, papulovesicular, or urticarial plaques. Because of the severity of the associated pruritus, many patients do not exhibit the primary skin lesions but have excoriations and crusted papules. Burning and stinging are also frequently reported along with the pruritus, and these symptoms are present prior to the manifestation of skin lesions. Almost all patients have an associated gluten-sensitive enteropathy, although it may be clinically unrecognized on presentation. Pathologically, the lesions demonstrate a neutrophilic inflammatory infiltrate in the dermal papillae. On immunofluorescence, granular deposits of IgA are found in the papillary dermis and along the epidermal basement membrane. The primary treatment of DH is dapsone at doses of 50–200 mg daily with most patients reporting remarkable improvement within 24–48 hours. At doses greater than 100 mg daily, one must pay close attention to side effects as methemoglobinemia and hemolysis frequently occur. In addition to dapsone, gluten-free diets are recommended. However, many months of the diet are required to achieve a clinical benefit and are not recommended as the sole treatment. Corticosteroids are not used in the treatment of DH.

XII-7.  The answer is A. (Chap. 54) The patient has discoid lupus erythematosus (DLE) or chronic cutaneous lupus erythematosus. It is characterized by discrete lesions most often on the face, scalp, or ears. The lesions are usually erythematous papules or plaques with a thick scale that occludes hair follicles. The lesions persist for years and grow slowly. Less than 10% of patients with DLE meet the criteria for systemic lupus erythematosus (SLE), although skin lesions are common in patients with SLE. Chronically, the lesions evolve to look similar to the one pictured. Treatment consists of topical or intralesional glucocorticoids. If that is ineffective, systemic therapy with an aminoquinoline antimalarial may be indicated. Systemic glucocorticoids or immunosuppressives are not indicated for localized disease. Although malignant melanoma may take on myriad appearances, the location, progress, and description of this lesion is more suggestive of discoid lupus; therefore, surgical excision and lymph node dissection are not indicated at this time. Vitamin E ointment has no proven role in the treatment of DLE.

XII-8.  The answer is C. (Chap. 55) Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are the most dreaded drug reactions and are characterized by diffuse blistering and epidermal necrosis with skin detachment. In both syndromes, the lesions typically begin with blisters developing over target lesions with mucosal involvement. In SJS, the amount of skin detachment is between 10% and 30% with the more severe TEN associated with skin detachment of more than 30%. Mortality is directly related to the amount of skin detachment with a mortality of about 10% in SJS and 30% in TEN. Other risk factors for mortality in SJS/TEN include older age and intestinal or pulmonary involvement. The most common drugs to cause SJS/TEN are sulfonamides, allopurinol, nevirapine, lamotrigine, aromatic anticonvulsants, and the oxicam nonsteroidal anti-inflammatory drugs (NSAIDs). There is no evidence that any therapy changes outcomes in SJS or TEN. Clearly, immediate cessation of the offending agent is necessary. Supportive therapy to prevent secondary infections is important. In many instances, these patients are treated in burn wards. Systemic corticosteroids may be useful for the short-term treatment of SJS/TEN, but these drugs increase long-term complications and have a higher associated mortality. Early data suggested that intravenous immunoglobulin (IVIG) may be helpful, but more recent studies have not shown benefit. Future studies are required to determine the role of IVIG in the treatment of SJS/TEN.

XII-9.  The answer is A. (Chap. 55) Morbilliform drug eruptions are the most common drug reactions. They typically begin on the trunk and consist of symmetric macules and papules that may become confluent. Moderate to severe pruritus is common. In contrast to Stevens-Johnson syndrome and toxic shock syndrome, involvement of the mucous membranes is uncommon. The principal differential diagnosis is viral exanthem, particularly in children. The rash usually develops within 1 week of initiation of therapy and resolves with discontinuation within 2 weeks. The most common drugs that cause morbilliform eruptions include penicillin derivatives, allopurinol, sulfonamides, and nonsteroidal anti-inflammatories. Urticaria consists of superficial well-defined wheals that are pruritic. Penicillins may cause IgE-mediated urticaria. Pemphigus is an autoimmune bullous disease of the skin and mucous membranes that is rarely associated with drugs such as penicillin.

XII-10. The answer is A. (Chap. 56) The UV spectrum reaching the earth is arbitrarily divided into two major segments: UV-A and UV-B. The outermost epidermal layer, the stratum corneum, is a major absorber of UV-B, and less than 10% of incident UV-B wavelengths penetrate through the epidermis to the dermis. In contrast, UV-A readily penetrates to the dermis. Photons in the UV-B are 1000-fold more efficient than photons in the UV-A in evoking the sunburn response. UV-B is primarily responsible for the sunburn response and for vitamin D photochemistry. UV-A is important in the pathogenesis of photoaging in human skin.

XII-11. The answer is A. (Chap. 167) Nontuberculous mycobacteria (NTM) were originally classified into “fast-growers” and “slow-growers” based on the length of time they took to grow in culture. Although more sophisticated tests have been developed, this classification scheme is still used and is of some benefit to the clinician. Fast-growing NTM include M. abscessus, M. fortuitum, and M. chelonae. They will typically take 7 days or less to grow on standard media, allowing relatively fast identification and drug-resistance testing. Slow-growing NTM include M. aviumM. marinumM. ulcerans, and M. kansasii. They often require special growth media and therefore a high pretest suspicion. The patient described likely has a cutaneous infection from one of the “fast-growing” NTM, which could be diagnosed with tissue biopsy, Gram stain, and culture.

XII-12. The answer is D. (Chap. 169) This vignette presents a patient with symptoms consistent with secondary syphilis. The causative organism of syphilis is Treponema pallidum, and it can penetrate normal skin to disseminate via the bloodstream long before the appearance of the typical skin lesion of primary syphilis. This lesion appears at the initial site of inoculation only after a period of 4–6 weeks. It will heal spontaneously, and symptoms of secondary syphilis begin approximately 6–8 weeks after it heals. However, as much as 15% of individuals will have evidence of healing chancres at the time of the manifestation of secondary syphilis. The primary manifestations of secondary syphilis are a generalized rash with generalized lymphadenopathy. The skin rash of secondary syphilis is most commonly macular or maculopapular and nonpuritic with a pink color. The rash begins on the trunk and upper extremities and classically progresses to involve the palms and soles. Ten percent of individuals with secondary syphilis also exhibit condylomata lata, which are papular lesions that develop in intertriginous areas. It is notable that the skin lesions of secondary syphilis do harbor bacteria and are infectious. A variety of constitutional symptoms can be present in secondary syphilis including malaise, fever, weight loss, sore throat, and headache.

Diagnosis of secondary syphilis in this patient with a prior diagnosis of syphilis is best accomplished by means of nontreponemal antibody testing. There are two common nontreponemal antibody tests: the rapid plasma reagin (RPR) test and the Venereal Disease Research Laboratory (VDRL) test. This patient’s prior syphilis infection was diagnosed and treated based on a positive RPR, which demonstrated the appropriate fourfold decrease in titers after appropriate therapy. As VDRL titers do not directly correspond to RPR titers, it is recommended that sequential testing be performed via the same nontreponemal test. In this case, that would be the RPR, as the VDRL would be difficult to interpret in the absence of previous titers. The fluorescent treponemal antibody test (FTA-Abs) is a specific treponemal antibody test. It does cross-react in the presence of other treponemal infections such as yaws or pinta. More importantly in this case, it remains positive after treatment of prior infection and lacks the ability to differentiate between new and past infections.

Primary HIV infection is certainly a concern in this patient given his risk factors. It can present similarly with a fever, rash, malaise, and generalized lymphadenopathy. The rash of primary HIV infection is also a maculopapular disseminated rash, but it is much less likely to affect the palms and soles. Acute HIV infection would be best diagnosed by obtaining an HIV viral load and would be reasonable to consider as additional testing in this patient, but would not yield the appropriate diagnosis. Given his recent negative antibody testing, the HIV antibody test would not likely be positive in the setting of recent infection.

XII-13. The answer is C. (Chap. 170) The lesion shown is typical of primary yaws skin infection caused by the endemic treponeme T. pallidum subsp. Pertenue. Yaws remains a health problem in parts of West Africa (including Ivory Coast and Ghana), Central Africa Republic, rural Congo, Indonesia, Papua New Guinea, Haiti, and parts of South America. India has not had a reported new case since 2003. As in syphilis, endemic treponemal infections typically have primary, secondary, and late stages. Yaws (also known as pian, framboesia, or bouba) is characterized by a primary raspberry-like lesion at the site of inoculation. Early skin lesions are infectious by contact and may persist for months. Cutaneous relapses are common, and late disease affects approximately 10% of patients with destructive skin, bone, and joint lesions. Primary infection is often associated with regional lymphadenopathy. Late yaws is characterized by gummas of the bones and skin. Destruction of the nose, maxilla, palate, and pharynx similar to leprosy and leishmaniasis may occur. Darkfield examination is diagnostic, and because of cross-reactivity the same serologic tests used for syphilis are positive. Therapy of yaws is based on treatment of syphilis because there are no controlled treatment trials of yaws. Penicillin, doxycycline, and tetracycline are thought to be effective therapies. Albendazole, ivermectin, and praziquantel are used for a variety of worm infections.

XII-14. The answer is C. (Chap. 174) The picture shows the characteristic rash of erythema migrans, the defining lesion of Lyme disease caused by Borrelia burgdorferi. Erythema migrans appears at the site of the tick bite within 3–32 days following the initial bite. It typically begins as a red macule or papule and expands slowly to form an annular lesion. As the lesion gets larger, the classic targetoid appearance develops with a bright red outer ring as well as ongoing erythema at the central lesion with clearing in between. The most common sites of erythema migrans are the classic locations of tick bites, including the groin, axilla, and thigh. The presence of this lesion in an endemic area for Lyme disease is an indication for treatment and does not require serologic confirmation.

Anaplasma phagocytophilum is the causative organism of human granulocytic anaplasmosis. This rickettsial disease is also transmitted through a tick bite and is prevalent in the upper Midwest, New England, parts of the Mid-Atlantic, and northern California. Rash occurs in about 6% of cases, although no specific rash is identified. The most common manifestations are fevers, malaise, and myalgia. Bartonella henselae (option B) is the organism responsible for cat-scratch fever, which can present with mild erythema near the site of the injury and markedly enlarged lymph nodes. Ehrlichia chaffeensis is another rickettsial organism that is transmitted by the bite of a tick and is common in the southeast, northeast, Texas, and California. Human monocytic ehrlichiosis is the disease causes by the organism and presents with nonspecific symptoms of fever, malaise, and myalgia. Rash is also not common in ehrlichiosis. Rickettsia rickettsii is the rickettsial organism responsible for Rocky Mountain spotted fever (RMSF). About 90% of individuals with RMSF have a rash during the course of the illness. The rash most commonly presents with diffuse macules beginning on the wrists and ankles, and spreading to the trunk.

XII-15. The answer is E. (Chap. 189) Dermatologic problems occur in more than 90% of patients with HIV infection. Seborrheic dermatitis is perhaps the most common rash in HIV-infected patients, affecting up to 50% of patients. The prevalence increases with falling CD4+ T-cell count. The rash involves the scalp and the face, appearing as described in the question. Therapy is standard topical treatment, although often a topical antifungal is added because of concomitant infection with Pityrosporum. Herpes zoster reactivation is painful and dermatomal, with progression of papules to vesicles to small pustules and then crusting. Molluscum contagiosum typically appears as one or many small pearly umbilicated asymptomatic papules occurring anywhere on the body. They can be a significant cosmetic issue in patients with AIDS. Psoriasis is not more common in patients with HIV infection but may be more severe and generalized. It would be uncommon to involve the face only. Kaposi’s sarcoma is due to coinfection with HHV-8 in patients with HIV/AIDS. It typically presents as more than one red/purple nodular painless lesion anywhere on the body.

XII-16. The answer is B. (Chap. 206) Tinea versicolor is the most common superficial skin infection. It is caused by lipophilic yeasts of the genus Malassezia, most commonly M. furfur. In tropical areas, the prevalence of tinea versicolor is 40–60%, whereas in temperate areas it is about 1%. In general, most individuals seek evaluation for cosmetic reasons as the lesions in tinea versicolor are asymptomatic or only mildly pruritic. The lesions typically appear as patches of pink or coppery-brown skin, but the areas may be hypopigmented in dark-skinned individuals. Diagnosis can be made by demonstrating the organism on potassium hydroxide preparation where a typical “spaghetti and meatballs” appearance may be seen. This is due to the presence of both spore forms and hyphal forms within the skin. Under long-wave UV-A light (Wood’s lamp), the affected areas fluoresce to yellow-green. The organism is sensitive to a variety of antifungals. Selenium sulfide shampoo, topical azoles, terbinafine, and ciclopirox have all been used with success. A 2-week treatment regimen typically shows good results, but the infection typically recurs within 2 years of initial treatment. Fusarium solani is an environmental fungus that usually causes infection in immunocompromised hosts. It can cause keratitis, onychomycosis, pneumonia, and hematogenous dissemination. Sporothrix schenckii is the usual etiologic agent of sporotrichosis. Penicillium marneffei is endemic in Vietnam, Thailand, and other southeast Asian countries. It causes a clinical syndrome similar to disseminated histoplasmosis. Trichophyton rubrum is a dermatophyte that causes ringworm.

XII-17. The answer is D. (Chap. 358) This patient has porphyria cutanea tarda (PCT). The major clinical feature of PCT is scarring skin lesions predominantly affecting the back of the hands that also may involve the forearms, face, legs, and feet. The lesions start as blisters that rupture and crust over, leaving scarring. Chronically, the areas most involved can develop thickened skin similar to systemic sclerosis. PCT is the most common porphyria; it usually occurs sporadically, but there is also a familial form. It is due to a deficiency of hepatic URO-decarboxylase, which must have more than 20% activity for symptoms. Excess hepatic iron is involved in the pathogenesis, and phlebotomy aiming for a low normal ferritin is a component of treatment. Precipitating factors should be avoided. Episodes are typically provoked by alcohol intake or sun exposure. Plasma porphyrins should be measured in patients suspected of PCT. Urinary ALA may be slightly increased, but urinary porphobilinogen is normal. Urine porphobilinogen is elevated during attacks of acute intermittent porphyria. ANA is utilized in the diagnosis of SLE, which may present with photosensitivity. Anti-SCL-70 is used to diagnose systemic sclerosis, which may also present with thick skin.

XII-18. The answer is D. (Chap. 397) Scabies, the human itch mite, remains a common problem due to its high degree of infectivity and ability to cause symptoms. It is a common reason for seeking attention from dermatologists and is thought to affect over 300 million people worldwide. Transfer is facilitated by intimate contact, and outbreaks may occur in nursing homes, mental institutions, and hospitals. The itching and rash associated with scabies derive from a sensitization reaction directed against the excreta that the mite deposits in its burrow. An initial infestation remains asymptomatic for up to 6 weeks, and a reinfestation produces a hypersensitivity reaction without delay. Intense itching worsens at night and after a hot shower. Typical burrows may be difficult to find because they are few in number and may be obscured by excoriations. Burrows appear as dark wavy lines in the epidermis and measure up to 15 mm. Lesions occur most frequently on the volar wrists, between the fingers, on the elbows, and on the penis. Small papules and vesicles, often accompanied by eczematous plaques, pustules, or nodules, are distributed symmetrically in those sites and in skinfolds under the breasts and around the navel, axillae, belt line, buttocks, upper thighs, and scrotum. Except in infants, the face, scalp, neck, palms, and soles are spared. Burrows should be sought and unroofed with a sterile needle or scalpel blade, and the scrapings should be examined microscopically for the mite, its eggs, and its fecal pellets. Permethrin cream is effective therapy. Ivermectin has not been approved by the U.S. Food and Drug Administration (FDA) for use against any form of scabies, but a single oral dose effectively treats scabies in otherwise healthy persons. Ceftriaxone plus azithromycin is recommended treatment for suspected gonorrhea and chlamydia infection, and metronidazole for trichomonas in women. The lesions shown in Figure XII-18 are not consistent with the single painless chancre of syphilis that is treated with penicillin G.

COLOR ATLAS

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FIGURE I-94

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FIGURE III-1 A-E

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FIGURE III-2

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FIGURE III-4

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FIGURE III-64

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FIGURE III-67

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FIGURE III-89

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FIGURE III-91

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FIGURE III-99

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FIGURE IV-13

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FIGURE IV-100

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FIGURE IV-104

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FIGURE IV-143

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FIGURE IV-173

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FIGURE IV-179

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FIGURE IV-188

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FIGURE IV-194 (Used with permission from Elizabeth M. Spiers, MD.)

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FIGURE IV-198

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FIGURE IV-210

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FIGURE IV-219

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FIGURE IV-245

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FIGURE IX-40

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FIGURE XII-3 (Courtesy of Robert Swerlick, MD; with permission.)

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FIGURE XII-5 (Courtesy of the Yale Resident’s Slide Collection; with permission.)

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FIGURE XII-7

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FIGURE XII-9

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FIGURE XII-12 (Courtesy of Jill McKenzie and Christina Marra.)

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FIGURE XII-13

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FIGURE XII-14 (Courtesy of Vijay K. Sikand, MD; with permission.)

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FIGURE XII-17 (Courtesy of Dr. Karl E. Anderson; with permission.)

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