AANP Family Nurse Practitioner (FNP) Certification ExamAssessmentMedium
A 35-year-old female presents with a 2-week history of a 'red, itchy rash' that started on her trunk and has spread to her extremities. She denies new medications, travel, or sick contacts. On examination, the nurse practitioner notes multiple oval-shaped, erythematous, slightly raised lesions with fine scaling, arranged in a 'Christmas tree' pattern on her back. A larger, solitary 'herald patch' is identified on her abdomen. What is the most likely diagnosis?
- APityriasis rosea
- BPsoriasis
- CEczema
- DTinea corporis
Show answer & explanationAnswer & explanation
Correct answer: A. Pityriasis rosea
Pityriasis rosea is classically characterized by a 'herald patch' (a single, larger oval lesion) followed by a generalized eruption of smaller, oval, erythematous, scaly lesions distributed in a 'Christmas tree' pattern on the trunk and proximal extremities. It is typically benign and self-limiting.
Why the other options are wrong
- B. Psoriasis presents with well-demarcated, erythematous plaques with thick, silvery scales, often on extensor surfaces, and does not have a herald patch or Christmas tree distribution.
- C. Eczema (atopic dermatitis) presents as intensely pruritic, erythematous patches and plaques, often with lichenification, typically in flexural areas, without a herald patch or Christmas tree pattern.
- D. Tinea corporis (ringworm) typically presents as annular lesions with central clearing and well-demarcated borders, not a 'Christmas tree' pattern.
Pityriasis Rosea
A common, self-limiting skin rash characterized by an initial 'herald patch' followed by a generalized eruption of oval, erythematous, scaly lesions in a 'Christmas tree' distribution.
- Herald patch precedes generalized rash.
- 'Christmas tree' pattern on trunk and extremities.
- Self-limiting, typically resolves in 6-8 weeks.
Memory trick: Rash Clues: Shape, Scale, and Spread