A 40-year-old man with a history of HIV infection presents to his physician due to the development of several skin lesions. The lesions erupted over the past few days, and are associated with fevers, chills, and a headache. He had no other medical problems and admits to being inconsistent in taking his antiretroviral medications. He works at a pet adoption center, has not recently traveled, and has no known sick contacts. On examination, there are several violaceous papular and nodular lesions that vary in appearance on the patient’s abdomen.
Which of the following is most likely responsible for these lesions?
Bartonella henselae. Both Kaposi sarcoma (due to HHV8) and bacillary angiomatosis (due to Bartonella henselae) affect AIDS patients and are in the differential diagnosis of cutaneous vascular proliferations. A skin biopsy is often necessary to differentiate the two conditions, and both can progress from localized skin lesions to widespread lesions with visceral involvement. When systemic symptoms such as fevers, chills, anorexia, and headache are present, the diagnosis of bacillary angiomatosis should be considered. Exposure to cats is a risk factor, and the infection responds to treatment with doxycycline or erythromycin. (B) Kaposi sarcoma is in the differential, but is less likely to have systemic symptoms. Of note, Kaposi sarcoma does not only occur in AIDS patients, but may affect solid organ transplant recipients, older men from the Mediterranean region (classic form), and those in Africa (endemic form). Treatment is with intralesional chemotherapy or systemic chemotherapy (doxorubicin) if the lesions are widespread or visceral.
(A) MAC occurs due to infection with M. avium or M. intracellulare and typically occurs in patients with a CD4 count <50/mm3 . MAC infection may manifest as localized disease (focal lymphadenitis) or as disseminated disease (fever, chills, night sweats, diarrhea, abdominal pain), but would not present with vascular skin lesions like the patient in this vignette. (C) HTLV-1 is associated with adult T-cell leukemia/lymphoma, which can have cutaneous manifestations but the lesions are typically patches, plaques, or nodules, and are not vascular like the lesions in this patient. (E) HPV can cause cervical or anal cancer in AIDS patients.
A 24-year-old medical student experiences an accidental needle stick from a patient known to have HIV.
Which of the following is the most appropriate management?
Tenofovir, emtricitabine, and raltegravir. The risk of acquiring HIV from a needle stick is 0.3%, and the risk from mucosal contact is 0.09%. Even though the risk is low, the risk can be eliminated with postexposure prophylaxis (PEP). Currently, a three-drug regimen is recommended, and the combination of tenofovir-emtricitabine (individually or as a combination pill) and raltegravir has a low risk of adverse effects. (B) The use of tenofovir-emtricitabine alone is thought to be less effective than the three-drug regimen. (C) Abacavir has a high rate of life-threatening hypersensitivity reactions, so the risk would outweigh the benefit. (D) Although the patient can refuse PEP if he desires, reassurance would not be appropriate since there is a small chance that he may acquire HIV.
A 38-year-old man presents to his physician complaining of fatigue, weight loss, cough, and shortness of breath. The symptoms have been present for 2 weeks now, and he has lost 4 kg over this time. He also complains of waking up in the middle of the night drenched with sweat. The cough is productive of yellow sputum and occasionally small amounts of blood. His medical history is significant for hypertension, for which he takes chlorthalidone, and he has a 12 pack-year smoking history. His temperature is 38.3°C, blood pressure is 138/88 mmHg, heart rate is 96 beats per minute, and respiratory rate is 24 breaths per minute. On examination, he has a normal S1 and S2 with no murmurs or gallops on auscultation. There is dullness to percussion over the right lower portion of his anterior chest, with decreased breath sounds over this area. A chest x-ray shows consolidation of the right middle lobe, and the right heart border is obscured. He is treated with antibiotics and is discharged. The patient follows up in clinic a couple of weeks later, and his laboratory values reveal elevated liver enzymes and uric acid.
Which of the following agents could cause both of these findings?
Pyrazinamide. This patient has primary TB, which presents with lobar consolidation typically of the lower lung segments (as opposed to reactivation of latent TB, which presents as an apical opacity; both primary and reactivation TB may have cavitation). It is important to know the treatment of active TB as well as the adverse effects of these medications. The treatment of active TB is “RIPE” therapy and can be remembered with the additional mnemonic of “4 for 2 and 2 for 4”: Rifampin, Isoniazid, Pyrazinamide, and Ethambutol for 2 months, then Rifampin and Isoniazid for 4 months. (Note: If drug-resistant TB is suspected, testing should be performed prior to initiating treatment to choose the most appropriate regimen.)
Toxicities of pyrazinamide include hepatitis, hyperuricemia, and a maculopapular rash. Isoniazid also causes hepatitis, but it does not cause hyperuricemia. Another common adverse effect of isoniazid is peripheral neuropathy, which is why vitamin B6 is given with isoniazid. One other high-yield toxicity is drug-induced lupus; other high-yield drugs that can cause this are hydralazine, procainamide, infliximab, and methyldopa. Rifampin causes orange discoloration of body fluids, hepatitis, and has many drug–drug interactions (induces many enzymes of the cytochrome P450 family). Ethambutol causes optic neuritis. (Ceftriaxone, Vancomycin, Trimethoprim-sulfamethoxazole, and Furosemide) None of these drugs are used in the treatment of TB. Furosemide and other diuretics can cause hyperuricemia but would not have been given to this patient.
A 42-year-old man who recently immigrated to the United States from Turkey presents with lower urinary tract symptoms. He reports that 4 months ago he had a localized rash on his trunk after swimming in a lake. Within the past few weeks, he has developed urinary urgency, frequency, and pain with urination. He has no history of kidney stones, UTIs, or congenital urinary tract abnormalities. He is afebrile with a normal physical examination. His laboratory values are significant for a hemoglobin of 11.1 g/dL, and a serum leukocyte differential shows eosinophilia. Microscopic analysis of the urine reveals numerous RBCs and parasite eggs.
If left untreated, which of the following is this patient at risk of developing?
Bladder cancer. Schistosoma species are parasites that are acquired through contact with fresh water. Many infections present initially as “swimmer’s itch,” which is a localized hypersensitivity reaction at the site where larvae enter through the skin. Once they enter the skin, they travel through the bloodstream to reach the liver and mature. Different species travel from the portal system to different areas of the body, causing variable disease manifestations. S. mansoni and S. japonicum produce disease of the liver and intestines, whereas S. haematobium produces disease of the urinary tract. There is an increased risk of squamous cell carcinoma of the bladder in patients with chronic infection due to S. haematobium.
(B) Other Schistosoma species that affect the liver and portal vein can cause portal hypertension. (C) Schistosomiasis is not associated with hemolytic anemia. This patient likely is anemic from blood loss in the urine. (D) Schistosomiasis can produce pulmonary hypertension by damaging the pulmonary vasculature; however, it will not cause airway disease. Airway disease such as asthma may be seen in parasite infections that involve the lungs as part of their lifecycle (e.g., Strongyloides stercoralis).
A 32-year-old man comes to the physician complaining of fever, shortness of breath, and a productive cough that has developed slowly over the past week. He has no other medical history and does not take any medications. His temperature is 38.5°C, blood pressure is 122/78 mmHg, heart rate is 68 beats per minute, respiratory rate is 18 breaths per minute, and oxygen saturation is 98% on room air. There are decreased breath sounds and dullness to percussion over the right lung base. The rest of the physical examination, including cardiac auscultation, is normal. A chest x-ray confirms consolidation of the right lower lobe.
What is the most appropriate course of action for this patient?
Outpatient treatment with azithromycin. This patient has typical symptoms of pneumonia (fever, productive cough, dyspnea), and the diagnosis is confirmed by chest x-ray. Because this patient is young and healthy with no comorbidities, he can be treated for CAP as an outpatient with a macrolide antibiotic. Atypical causes of pneumonia (Mycoplasma, Chlamydia, viruses) are common in this age group; however, the specific pathogen cannot be reliably determined based on the symptoms/signs or chest x-ray. (B) If the decision is made to treat the patient as an outpatient, it is unnecessary to order blood and sputum cultures since empiric antibiotic treatment is almost always successful. An exception to this is macrolide-resistant S. pneumoniae, which should be considered in patients from a high resistance area or in patients who took a macrolide antibiotic in the last few months. Even if blood and sputum cultures are sent, empiric antibiotics should be started immediately and then changed if necessary based on the culture data. (C, D) Deciding whether or not to admit a patient is based on many factors, and tools such as the pneumonia severity index, CURB-65, and SMART-COP (to determine the need for intensive care) can help in making this decision. Though this is low yield for the shelf examination, it might be helpful to know CURB65: confusion, uremia/BUN ≥20 mg/dL, respirations ≥30 breaths per minute, blood pressure <90/60 mmHg, age ≥65 years. Scores of 0 to 1 can be treated as an outpatient, a score of 2 should be treated as an inpatient, and scores ≥3 may benefit from intensive care.
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