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A 38-year-old Hispanic woman presents with a rash on her forearms, wrists, ankle, and back (Figures 154-1, 154-2, 154-3, and 154-4). She states the rash is mildly itchy and she does not like the way it looks. She would like some medication to make this better. Lichen planus (LP) was diagnosed and clobetasol was prescribed to keep the LP under better control.

Figure 154-1

A 38-year-old Hispanic woman with lichen planus on her wrist. (Courtesy of Richard P. Usatine, MD.)

Figure 154-2

Close-up of wrist showing linearity of the lesions on the flexor surface. Lesions may be pink rather than purple. (Courtesy of Richard P. Usatine, MD.)

Figure 154-3

Ankle of the woman in Figure 154-1 with typical lichen planus eruption. (Courtesy of Richard P. Usatine, MD.)

Figure 154-4

A. Lichen planus on the back of the woman in Figure 154-1. B. Close-up of lesions on the back showing Wickham striae crossing the flat papules of lichen planus. These lines are white and reticular like a net. (Courtesy of Richard P. Usatine, MD.)

LP is a self-limited, recurrent, or chronic autoimmune disease affecting the skin, oral mucosa, and genitalia. LP is generally diagnosed clinically with lesions classically described using the six Ps (planar, purple, polygonal, pruritic, papules, and plaques).

  • LP is an inflammatory dermatosis of skin or mucous membranes that occurs in approximately 1% of all new patients seen at healthcare clinics.1
  • Although most cases occur between ages 30 and 60 years, LP can occur at any age.1,2
  • There may be a slight female predominance.2-4

  • Usually idiopathic, thought to be a cell-mediated immune response to an unknown antigen.2,3,5
  • Possible human leukocyte antigen (HLA)-associated genetic predisposition.2
  • Lichenoid-type reactions may be associated with medications (e.g., angiotensin-converting enzyme inhibitors [ACEIs], thiazide-type diuretics, tetracycline, chloroquine), metals (e.g., gold, mercury), or infections (e.g., secondary syphilis).2,5
  • Associated with liver disease, especially related to hepatitis C virus.2,5,6
  • LP may be found with other diseases of altered immunity (e.g., ulcerative colitis, alopecia areata, myasthenia gravis).1
  • Malignant transformation has been reported in ulcerative oral lesions in men.1

  • Possible HLA-associated genetic predisposition.
  • Hepatitis C virus infection, although causal relationship is not established.6
  • Certain drugs (see “Etiology and Pathophysiology”).

Clinical Features

  • Classically, the six Ps of LP are planar, purple, polygonal, pruritic, papules, and plaques ...

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