A 22-year-old college student comes to the office due to a rash. She found an oval, pink spot on her chest while taking a shower a week ago. The next day, the spot developed a slight scale and began to itch. Three days later, several additional smaller lesions appeared on her upper chest; then the rash spread downward over the rest of the trunk. The lesions are mildly pruritic. The patient has no blisters, bullae, mucous membrane involvement, or lesions on the palms or soles. Medical history is unremarkable, and she does not use tobacco, alcohol, or illicit drugs. The patient is sexually active with 1 partner, and her only medication is an oral contraceptive.
Vital signs are normal. Examination findings are shown in the image.

Which of the following is the most likely diagnosis in this patient?

Question

A 22-year-old college student comes to the office due to a rash.  She found an oval, pink spot on her chest while taking a shower a week ago.  The next day, the spot developed a slight scale and began to itch.  Three days later, several additional smaller lesions appeared on her upper chest; then the rash spread downward over the rest of the trunk.  The lesions are mildly pruritic.  The patient has no blisters, bullae, mucous membrane involvement, or lesions on the palms or soles.  Medical history is unremarkable, and she does not use tobacco, alcohol, or illicit drugs.  The patient is sexually active with 1 partner, and her only medication is an oral contraceptive.
Vital signs are normal.  Examination findings are shown in the image.

Which of the following is the most likely diagnosis in this patient?

Quizplus · Accepted Answer

This patient has a widespread outbreak of pruritic plaques consistent with pityriasis rosea (PR). PR predominantly affects the trunk, neck, and proximal limbs and is most common in adolescents and young adults. It is thought to have a viral etiology, and is often associated with a nonspecific, mild, flu-like prodrome. PR typically begins with a single, large, scaly, salmon-colored lesion (herald patch), but numerous smaller lesions develop rapidly thereafter. The secondary lesions occasionally may be oriented parallel to skinfolds in a "Christmas tree" pattern. The diagnosis of PR is usually based on clinical features. Skin scrapings may be helpful for differentiating an isolated herald patch from tinea corporis, although the acute onset usually makes the distinction obvious. PR is a self-limited disorder, but the lesions may take a few months to resolve. Pruritus can be managed with topical glucocorticoids or oral antihistamines. Phototherapy can be considered for more severe or persistent cases, but symptomatic therapy and simple reassurance is adequate for most patients. (Choice A) Guttate psoriasis presents with scattered, erythematous, scaly papules and plaques. It typically follows a streptococcal infection. Compared with the lesions of PR, guttate psoriasis lesions are thicker and have a more prominent scale. Also, the herald patch in this patient makes the diagnosis of PR much more likely. Guttate psoriasis (Choice B) Lichen planus is characterized by the "5 Ps": Polygonal, Planar, Pruritic, Purplish Plaques on the wrists, hands, trunk, and legs. Fine white lines termed "Wickham striae" may be present on the plaque surface. Lichen planus (Choice D) The papulosquamous eruption of secondary syphilis may resemble PR but without a herald patch. Unlike PR, secondary syphilis does not spare the palms and soles. secondary syphilis (Choice E) Tinea versicolor is characterized by hypo- or hyperpigmented patches affecting the trunk, neck, and proximal limbs. The lesions may have a fine scale, but unlike PR, the lesions are otherwise flat. Its onset is more insidious than that of PR. Tinea versicolor Educational objective: Pityriasis rosea is characterized by mildly pruritic, salmon-colored plaques involving the trunk, neck, and proximal limbs. It typically begins with a single large lesion (herald patch). The diagnosis is usually made based on clinical features. The condition is self-limited, and most patients require only reassurance and symptomatic treatment. __________ References: Pityriasis, rosea. (http://www.ncbi.nlm.nih.gov/pubmed/28846360)

A 22-Year-Old College Student Comes to the Office Due to a Rash