brand logo

Am Fam Physician. 2022;106(4):453-454

Author disclosure: No relevant financial relationships.

A 52-year-old woman presented with a moderately pruritic rash on her right leg that developed several months earlier. She did not have blisters, cough, sore throat, chills, diarrhea, fevers, or joint aches. She had no recent infections or household contacts with a similar rash. She was not using any new medications or personal care products. No improvement was noted after two weeks of treatment with oral prednisone.

Physical examination revealed a purple papular eruption extending in a streak pattern from the medial aspect of the right thigh to the posteromedial aspect of the right calf (Figure 1). Close examination revealed fine white lines within purple plaques. Vital signs were normal.


Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?

  • A. Follicular keratosis.

  • B. Inflammatory linear verrucous epidermal nevus.

  • C. Lichen striatus.

  • D. Linear lichen planus.

  • E. Linear psoriasis.


The answer is D: linear lichen planus. The prevalence of lichen planus is 0.5% to 1%. Linear lichen planus is a rare form of the condition (less than 1% of cases) that usually presents as unilateral pruritic, violaceous, flat-topped papules in a linear distribution on the limbs.1 Fine white lines on top of the plaques (Wickham striae) may be seen. The underlying cause of lichen planus is unknown, although the linear form may be associated with a dermatomal pattern or the Koebner phenomenon at the site of trauma.2 Classic lesions present with the four P's: purple, pruritus, polygonal, and papules/plaques.

Already a member/subscriber?  Log In


From $165
  • Immediate, unlimited access to all AFP content
  • More than 130 CME credits/year
  • AAFP app access
  • Print delivery available

Issue Access

  • Immediate, unlimited access to this issue's content
  • CME credits
  • AAFP app access
  • Print delivery available
Purchase Access:  Learn More

The editors of AFP welcome submissions for Photo Quiz. Guidelines for preparing and submitting a Photo Quiz manuscript can be found in the Authors' Guide at To be considered for publication, submissions must meet these guidelines. Email submissions to

This series is coordinated by John E. Delzell Jr., MD, MSPH, associate medical editor.

A collection of Photo Quiz published in AFP is available at

Continue Reading

More in AFP

More in PubMed

Copyright © 2022 by the American Academy of Family Physicians.

This content is owned by the AAFP. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP.  See permissions for copyright questions and/or permission requests.