A 16-year-old girl comes to the clinic due to a rash. The patient developed a pruritic red lesion on her back 5 days ago that has slowly grown. She has since developed multiple new lesions on the chest and back. The patient has tried over-the-counter topical antibiotics with no improvement. She also had a fever, headache, and malaise about a week ago, which resolved after 2 days. She has no chronic medical conditions, takes no medications, and has no allergies. The patient is a wrestler for her high school team. She is sexually active and uses combination oral contraceptives. Temperature is 37.2 C (99 F). Cardiopulmonary examination is normal. Skin examination shows multiple 0.5- to 1-cm (0.2- to 0.4-in) erythematous macules with minimal scaling on the chest, as seen in the exhibit, and back oriented along the lines of tension. There is a larger, 3-cm (1.2-in) erythematous patch on the upper back with scaling. The rash spares the palms and soles. Which of the following is the most likely diagnosis in this patient?

Question

A 16-year-old girl comes to the clinic due to a rash.  The patient developed a pruritic red lesion on her back 5 days ago that has slowly grown.  She has since developed multiple new lesions on the chest and back.  The patient has tried over-the-counter topical antibiotics with no improvement.  She also had a fever, headache, and malaise about a week ago, which resolved after 2 days.  She has no chronic medical conditions, takes no medications, and has no allergies.  The patient is a wrestler for her high school team.  She is sexually active and uses combination oral contraceptives.  Temperature is 37.2 C (99 F).  Cardiopulmonary examination is normal.  Skin examination shows multiple 0.5- to 1-cm (0.2- to 0.4-in) erythematous macules with minimal scaling on the chest, as seen in the exhibit, and back oriented along the lines of tension.  There is a larger, 3-cm (1.2-in) erythematous patch on the upper back with scaling.  The rash spares the palms and soles.  Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

11ec25c8_d64a_8f4a_bc81_3f78a48b26b0_MD0003_00 Pityriasis rosea is a common skin condition that typically presents from early adolescence to young adulthood. The rash classically begins with a herald patch, an erythematous, annular lesion on the trunk. This patch may increase in size and develop scaling around the edge. Within a week, clusters of smaller, erythematous, oval lesions appear on the trunk. These scaly macules and papules are typically distributed obliquely along the lines of tension in a "Christmas tree" pattern, most noticeable on the back. The rash is often asymptomatic but may be associated with mild pruritus. A viral prodrome may precede pityriasis rosea, as seen in this patient with preceding fever, headache, and malaise. Pityriasis rosea Pityriasis rosea is self-limited and spontaneously resolves within weeks to months. Management is reassurance alone, although symptomatic relief of pruritus (eg, antihistamines, topical corticosteroids) may be indicated. (Choice A) Erythema multiforme consists of erythematous target lesions with a dusky center that may be precipitated by infection or medication. Scaling, as seen in this patient, would not be expected. Erythema multiforme (Choice B) Nummular eczema is a chronic rash characterized by dry, erythematous, and intensely pruritic patches on the extremities. It is less likely in this adolescent with an acute, mildly pruritic rash on the trunk. Nummular eczema (Choice D) Erythema marginatum, a faintly erythematous, ring-like rash that comes and goes, is a manifestation of acute rheumatic fever, which is unlikely in this patient with no preceding streptococcal infection. Erythema marginatum (Choice E) The exanthem of secondary syphilis is variable but most commonly presents with a diffuse, maculopapular rash. Involvement of the palms and soles is classic and not seen in this patient. (Choice F) Tinea corporis, which often occurs in athletes who have direct skin contact (eg, wrestlers), presents with an erythematous, scaly, pruritic patch. Lesions typically have central clearing and raised borders. In contrast, this patient has a rash in a "Christmas tree" distribution without central clearing. Educational objective: Pityriasis rosea is a self-limited exanthem that classically begins with a solitary, large herald patch followed by clusters of smaller oval lesions oriented in a "Christmas tree" pattern. Management is reassurance alone, although symptomatic relief of pruritus (eg, antihistamines, topical corticosteroids) may be indicated. Tinea corporis References: Pityriasis rosea: a comprehensive classification. (http://www.ncbi.nlm.nih.gov/pubmed/27096928)

A 16-Year-Old Girl Comes to the Clinic Due to a Rash