A 47-year-old woman comes to the office due to an itchy rash. For the last 3 months, she has had a gradual onset of multiple pruritic lesions at her wrists, legs, and ankles. The patient tried treating the lesions with emollients and topical over-the-counter hydrocortisone but had no relief. Examination shows scattered, scaly, pink papules and plaques as shown in the exhibit.
Which of the following is the most likely diagnosis?

Question

A 47-year-old woman comes to the office due to an itchy rash.  For the last 3 months, she has had a gradual onset of multiple pruritic lesions at her wrists, legs, and ankles.  The patient tried treating the lesions with emollients and topical over-the-counter hydrocortisone but had no relief.  Examination shows scattered, scaly, pink papules and plaques as shown in the exhibit. 
 Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec160b_38fb_f3bd_9249_fd7c8523c59d_MD0001_00 This patient has lichen planus (LP), an immune-mediated condition that typically presents with pruritic, pink papules and plaques. LP lesions often have lacy, scaly, white markings (Wickham striae) and can form at sites of minor trauma (Köbner phenomenon). The skin lesions typically occur symmetrically on the flexural surfaces of the wrists and ankles but can also involve the nails, oral mucous membranes, and genitalia. The pathologic process in LP is characterized by a (CD8⁺) T cell-mediated response against cells along the dermal-epidermal junction. Although the etiology is unknown, the risk may be increased in patients with hepatitis C and those taking certain medications (eg, ACE inhibitors, thiazide diuretics). LP typically follows a chronic course with gradual, spontaneous remission within 2 years. (Choice A) Actinic keratosis presents with small, hyperkeratotic plaques in sun-exposed areas (eg, forehead, cheeks). It is most common in patients age >60, and itching is atypical. (Choice B) Atopic dermatitis typically occurs in large patches at the flexural surfaces of the extremities, especially the elbows; it usually presents in childhood, and most patients have a history of other atopic disorders (eg, allergic rhinitis, asthma). (Choice C) Irritant contact dermatitis is due to repeated exposure to irritants (eg, detergents, solvents, oxidizing agents). It presents as hyperkeratotic patches with fissuring and scaling, most commonly on the hands. (Choice E) Psoriasis is an immune-mediated inflammatory disease that usually presents with thick, erythematous plaques with silvery scales on the extensor surfaces of the knees and elbows, scalp, or neck. Educational objective: Lichen planus is an immune-mediated condition that presents with pruritic, pink papules and plaques, often with lacy, scaly, white markings (Wickham striae). The lesions typically occur on the flexural surfaces of the wrists and ankles but can also involve the nails, oral mucous membranes, and genitalia. __________ References: Update on lichen planus and its clinical variants. (http://www.ncbi.nlm.nih.gov/pubmed/28491978)

A 47-Year-Old Woman Comes to the Office Due to an Itchy