A 49-year-old man comes to the office for evaluation of a pruritic rash on his back. The rash has been present for a few months and has been unrelenting. The itching disturbs his sleep, and over-the-counter antihistamines have not helped. Medical history is significant for primary hypertension, for which he takes hydrochlorothiazide and lisinopril. Vital signs are normal. The patient's skin findings are shown in the image below: Which of the following is the most likely diagnosis?

Question

A 49-year-old man comes to the office for evaluation of a pruritic rash on his back.  The rash has been present for a few months and has been unrelenting.  The itching disturbs his sleep, and over-the-counter antihistamines have not helped.  Medical history is significant for primary hypertension, for which he takes hydrochlorothiazide and lisinopril.  Vital signs are normal.  The patient's skin findings are shown in the image below:  Which of the following is the most likely diagnosis?

Quizplus · Accepted Answer

11ec25c8_d37f_879e_bc81_a9ede18df0e4_MD0003_00 This patient has a pruritic rash consistent with lichen planus (LP). The skin lesions in LP are characterized by the "5 P's": pruritic, purple/pink, polygonal papules and plaques. The lesions often show white, lacy markings known as Wickham striae and can form along lines of minor trauma or scratching (Köbner phenomenon). Wickham striae LP is usually idiopathic, although it is often seen in patients with hepatitis C. However, drug-induced LP (lichenoid drug reaction) has been associated with a number of medications, including ACE inhibitors, thiazide diuretics, beta blockers, and hydroxychloroquine. Drug-induced LP typically has a more diffuse presentation than idiopathic LP, which is frequently limited to the flexor surfaces of the wrists and ankles, oral mucosa, and genitalia. Treatment of drug-induced LP includes topical high-potency glucocorticoids and discontinuation of the offending medication. Some patients may develop recurrent bouts despite drug discontinuation, and residual hyperpigmentation is common. (Choice A) Atopic dermatitis causes a pruritic rash affecting the flexor surfaces of the extremities. It usually presents in childhood, and most patients have a history of other atopic disorders (eg, allergic rhinitis, asthma). (Choice B) Dermatitis herpetiformis causes pruritic, erythematous papules, vesicles, and bullae on the extensor surfaces of the elbows, back, knees, and buttocks. It is generally seen in patients with gluten-sensitive enteropathy (celiac disease). (Choice D) Pityriasis rosea begins with an erythematous annular lesion on the trunk ("herald patch"), followed by an outbreak of macules and papules across the neck, trunk, and proximal limbs. It is often preceded by a nonspecific viral prodrome. Pityriasis is most common in adolescents and young adults and usually resolves within 4-6 weeks. (Choice E) Psoriasis is characterized by sharply demarcated, erythematous plaques with a thick, silvery scale involving the scalp, extensor surfaces of the knees and elbows, neck, and back. erythematous plaques (Choice F) Tinea versicolor is a common superficial fungal dermatosis that usually presents with patches of altered pigmentation and faint scaling. The lesions are generally flat, and pruritis is mild or absent. altered pigmentation Educational objective: Drug-induced lichen planus (lichenoid drug reaction) is associated with a number of medications, including ACE inhibitors, thiazide diuretics, beta blockers, and hydroxychloroquine. Whereas idiopathic lichen planus occurs most commonly at the wrists and ankles, drug-induced lichen planus can have a more diffuse presentation. Treatment includes topical glucocorticoids and discontinuation of the suspected medication. References: Severe drug-induced dermatoses. (http://www.ncbi.nlm.nih.gov/pubmed/25037258)

A 49-Year-Old Man Comes to the Office for Evaluation of a Pruritic