Infectious skin diseases — MCQs

A 14-month-old boy is brought to the clinic for evaluation of a rash. The rash started on the face and spread to the trunk. He also had a fever and cough for the past 2 days. His mother says that they recently immigrated from Asia and cannot provide vaccination records. The physical examination reveals a maculopapular rash on the face, trunk, and proximal limbs with no lymphadenopathy. Blue-white spots are noted on the oral mucosa and there is bilateral mild conjunctival injection. The causative agent of this condition belongs to which of the following virus families?

Physical exam of a 15-year-old female reveals impetigo around her mouth. A sample of the pus is taken and cultured. Growth reveals gram-positive cocci in chains that are bacitracin sensitive. Which of the following symptoms would be concerning for a serious sequela of this skin infection?

A 3-year-old boy is brought to the physician because of a 3-day history of a pruritic skin rash on his chest. His mother says that he has no history of dermatological problems. He was born at term and has been healthy except for recurrent episodes of otitis media. His immunizations are up-to-date. He appears pale. His temperature is 37°C (98.6°F), pulse is 110/min, respirations are 26/min, and blood pressure is 102/62 mm Hg. Examination shows vesicles and flaccid bullae with thin brown crusts on the chest. Lateral traction of the surrounding skin leads to sloughing. Examination of the oral mucosa shows no abnormalities. Complete blood count is within the reference range. Which of the following is the most likely diagnosis?

A 25-year-old man presents with multiple brownish patches on his trunk that appeared suddenly after exercising in hot weather. The lesions don't itch or scale. Wood's lamp examination shows yellow-green fluorescence. Which of the following is the most appropriate treatment?

A 32-year-old man with a past medical history significant for HIV and a social history of multiple sexual partners presents with new skin findings. His past surgical and family histories are noncontributory. The patient's blood pressure is 129/75 mm Hg, the pulse is 66/min, the respiratory rate is 16/min, and the temperature is 37.5°C (99.6°F). Physical examination reveals numerous painless skin-colored, flattened and papilliform lesions along the penile shaft and around the anus on physical exam. The application of 5% acetic acid solution causes the lesions to turn white. What is the etiology of these lesions?

A 17-year-old boy comes to the physician because of a nonpruritic rash on his chest for 1 week. He returned from a trip to Puerto Rico 10 days ago. He started using a new laundry detergent after returning. He has type 1 diabetes mellitus controlled with insulin. His mother has Hashimoto thyroiditis, and his sister has severe facial acne. Examination of the skin shows multiple, nontender, round, hypopigmented macules on the chest and trunk. There is fine scaling when the lesions are scraped with a spatula. Which of the following is the most likely underlying mechanism of this patient's symptoms?

A 10-month-old girl is brought to the clinic by her mother with skin lesions on her chest. The mother says that she noticed the lesions 24 hours ago and that they have not improved. The patient has no significant past medical history. She was born at term by spontaneous transvaginal delivery with no complications, is in the 90th percentile on her growth curve, and has met all developmental milestones. Upon physical examination, several skin-colored umbilicated papules are visible. Which of the following is the most appropriate treatment of this patient's likely diagnosis?

A 24-year-old man presents to the emergency department with sudden onset of fever for the past few hours as well as pain and swelling in his right knee and left ankle. He denies any recent history of trauma or injury. The patient is otherwise a healthy, active young man. He recently recovered from a case of gastroenteritis which caused significant abdominal pain and bloody stool 4 weeks ago. He believes the infection was related to eating undercooked chicken while camping. His blood pressure is 124/76 mm Hg, his heart rate is 76/min, and his temperature is 36.9 ℃ (98.4 ℉). Physical examination reveals tenderness to palpation of his right knee and left ankle as well as erythematous conjunctiva. Which of the following features would be least likely to develop in patients with this condition?

You are seeing an otherwise healthy 66-year-old male in clinic who is complaining of localized back pain and a new rash. On physical exam, his vital signs are within normal limits. You note a vesicular rash restricted to the upper left side of his back. In order to confirm your suspected diagnosis, you perform a diagnostic test. What would you expect to find on the diagnostic test that was performed?

A 56-year-old woman, gravida 3, para 3, comes to the physician because her left breast has become larger, hot, and itchy over the past 2 months. The patient felt a small lump in her left breast 1 year ago but did not seek medical attention at that time. She has hypertension and hyperlipidemia. Menarche was at the age of 11 years and menopause at the age of 46 years. Her mother died of breast cancer at the age of 45 years. The patient does not smoke or drink alcohol. Current medications include labetalol, simvastatin, and daily low-dose aspirin. She is 170 cm (5 ft 7 in) tall and weighs 78 kg (172 lb); BMI is 27 kg/m2. Her temperature is 37.7°C (99.9°F), pulse is 78/min, and blood pressure is 138/88 mm Hg. Examination shows large dense breasts. There is widespread erythema and edematous skin plaques over a breast mass in the left breast. The left breast is tender to touch and left-sided axillary lymphadenopathy is noted. Which of the following is the most likely diagnosis?