Lesions evolve from macular to petechial, start on the wrists and ankles, spread centripetally, and appear on the palms and soles only later in the disease.








Complications of Injecting Drug Use

  • Local problems—Abscess (Figures 240-2 
    Image not available.

    A 32-year-old woman with type 1 diabetes developed large abscesses all over her body secondary to injection of cocaine and heroin. Her back shows the large scars remaining after the healing of these abscesses. (Courtesy of ­Richard P. Usatine, MD.)

    and 240-3; Abscess), cellulitis, septic thrombophlebitis, local induration, necrotizing fasciitis, gas gangrene, pyomyositis, mycotic aneurysm, compartmental syndromes, and foreign bodies (e.g., broken needle parts) in local areas.2
    • IDUs are at higher risk of getting methicillin-resistant Staphylococcus aureus(MRSA) skin infections that the patient may think are spider bites (Figure 240-4).
    • Some IDUs give up trying to inject into their veins and put the cocaine directly into the skin. This causes local skin necrosis that produces round atrophic scars (Figure 240-5).
  • IDUs are at risk for contracting systemic infections, including HIV and hepatitis B or hepatitis C.
    • Injecting drug users are at risk of endocarditis, osteomyelitis (Figures 240-6and 240-7), and an abscess of the epidural region. These infections can lead to long hospitalizations for intravenous antibiotics. The endocarditis that occurs in IDUs involves the right-sided heart valves (see Chapter 50, Bacterial Endocarditis).2 They are also at risk of septic emboli to the lungs, group A β-hemolytic streptococcal septicemia, septic arthritis, and candidal and other fungal infections.


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A 47-year-old man from North Carolina with no known past medical history presents in August with a 2-day history of abdominal pain, diffuse myalgias, and debilitating headache. He has not traveled out of the state recently but does report that he spent a day 2 weeks ago clearing a nearby field in preparation for planting a garden and that 1 week ago he ate raw oysters. On examination, you note that the patient has blanchable macules on his wrists and ankles. You promptly admit him to the hospital for treatment, noting that his disease carries a mortality rate of approximately 40% if not treated appropriately. Which pathogen is likely responsible for this patient’s disease?

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The correct answer is B. You answered D.

The answer is B.(Chap. 24) This patient likely has Rocky Mountain spotted fever (RMSF), which is caused by Rickettsia rickettsii. Most common in the southwestern and southeastern United States, it is spread by tick vector. The patient likely was exposed by tick bite when clearing the field; many patients neither notice nor report a history of tick bite. The absence of noted tick exposure should not rule out this serious disease. The rash of RMSF classically begins on the wrists and ankles and spreads centripetally, appearing on palms and soles later in disease. Lesions can evolve from blanchable macules to petechiae. RMSF requires prompt treatment because mortality of the untreated disease is approximately 40%. Borrelia burgdorferi causes Lyme disease, which is classically associated with the erythema migrans rash, a papule expanding to an erythematous annular lesion with central clearing. Spirillum minis is an etiologic agent of rat-bite fever. Its rash is characterized by an eschar at bite site and then a blotchy violaceous or red-brown rash involving the trunk and extremities. Salmonella typhi is the etiologic agent in typhoid fever, which is usually contracted via contaminated food or water (though it is rare in the United States). Its rash usually consists of transient, blanchable erythematous macules and papules, 2–4 mm, usually on the trunk. Finally, although Vibrio vulnificus is classically associated with exposure to contaminated saltwater (e.g., raw oysters) and carries a high mortality, its rash is characterized by hemorrhagic bullae. It is often most common in patients with underlying liver disease, diabetes, or renal failure.


A 75-year-old triathlete complains of gradually worsening vision over the past year. It seems to be involving near and far vision. The patient has never required corrective lenses and has no significant medical history other than diet-controlled hypertension. He takes no regular medications. Physical examination is normal except for bilateral visual acuity of 20/100. There are no focal visual field defects and no redness of the eyes or eyelids. Which of the following is the most likely diagnosis?

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The correct answer is A. You answered A.

Age-related macular degeneration is a major cause of painless, gradual bilateral central visual loss. It occurs as nonexudative (dry) or exudative (wet) forms. Recent genetic data have shown an association with the alternative complement pathway gene for complement factor H. The mechanism link for that association is unknown. The nonexudative form is associated with retinal drusen that leads to retinal atrophy. Treatment with vitamin C, vitamin E, beta-carotene, and zinc may retard the visual loss. Exudative macular degeneration, which is less common, is caused by neovascular proliferation and leakage of choroidal blood vessels. Acute visual loss may occur because of bleeding. Exudative macular degeneration may be treated with intraocular injection of a vascular endothelial growth factor antagonist (bevacizumab or ranibizumab). Blepharitis is inflammation of the eyelids usually related to acne rosacea, seborrheic dermatitis, or staphylococcal infection. Diabetic retinopathy, now a leading cause of blindness in the United States, causes gradual bilateral visual loss in patients with long-standing diabetes. Retinal detachment is usually unilateral and causes visual loss and an afferent pupillary defect.


Mr. Jenson is a 40-year-old man with a congenital bicuspid aortic valve who you have been seeing for more than a decade. You obtain an echocardiogram every other year to follow the progression of his disease knowing that bicuspid valves often develop stenosis or regurgitation requiring replacement in middle age. Given his specific congenital abnormality, what other anatomic structure is important to follow on his biannual echocardiograms?

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The correct answer is A. You answered A.

The answer is A. (Chap. 282) Bicuspid aortic valve is among the most common of congenital heart cardiac abnormalities. Valvular function is often normal in early life and thus may escape detection. Due to abnormal flow dynamics through the bicuspid aortic valve, the valve leaflets can become rigid and fibrosed, leading to either stenosis or regurgitation. However, pathology in patients with bicuspid aortic valve is not limited to the valve alone. The ascending aorta is often dilated, misnamed “poststenotic” dilatation; this is due to histologic abnormalities of the aortic media and may result in aortic dissection. It is important to screen specifically for aortopathy because dissection is a common cause of sudden death in these patients.



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