A 46-year-old man comes to the physician's office for a pruritic rash. The patient was in his usual state of health until 2 months ago, when dark red lesions appeared over his wrists. The lesions progressed, and a few weeks later he developed similar lesions on his lower legs. This morning, the patient saw some "white lines" in his mouth and called for an urgent appointment. He has no fevers, chills, weight loss, or diarrhea. The patient has a history of hypertension, which is controlled with lisinopril. He does not use tobacco or alcohol, but has a remote history of intravenous drug use. Physical examination shows multiple, discrete violaceous papules and plaques over the flexural surfaces of the patient's wrists and lower legs as shown in the image below. Examination of the buccal mucosa shows whitish lacy streaks with a slight background erythema. The rest of his physical examination is unremarkable.
Which of the following is the best next step in diagnosing this patient's condition?

Question

A 46-year-old man comes to the physician's office for a pruritic rash.  The patient was in his usual state of health until 2 months ago, when dark red lesions appeared over his wrists.  The lesions progressed, and a few weeks later he developed similar lesions on his lower legs.  This morning, the patient saw some "white lines" in his mouth and called for an urgent appointment.  He has no fevers, chills, weight loss, or diarrhea.  The patient has a history of hypertension, which is controlled with lisinopril.  He does not use tobacco or alcohol, but has a remote history of intravenous drug use.  Physical examination shows multiple, discrete violaceous papules and plaques over the flexural surfaces of the patient's wrists and lower legs as shown in the image below.  Examination of the buccal mucosa shows whitish lacy streaks with a slight background erythema.  The rest of his physical examination is unremarkable.  
Which of the following is the best next step in diagnosing this patient's condition?

Quizplus · Accepted Answer

Explanation: Lichen planus (LP) is an immunologically mediated skin disorder, affecting mostly middle-aged adults. It typically involves the skin, nails, mucous membranes of the mouth, and external genitalia (vulva and penis). The classic skin lesions are shiny, discrete, intensely pruritic, polygonal-shaped violaceous plaques and papules that are most frequent on the flexural surfaces of the extremities. Wrists are a common site of skin involvement. A characteristic whitish, lacy pattern, referred to as Wickham striae, is seen often on the lesion surfaces. Mucosal lesions may appear as papular, atrophic, erosive lesions or may present solely as lacelike, reticular Wickham striae, especially on the tongue and buccal mucosa. Genital LP presents usually with intensely pruritic violaceous papules on the glans penis or vulva. skin lesions The diagnosis of LP is mainly clinical, based on classic skin lesions in a characteristic distribution. If it becomes necessary to confirm the diagnosis, a punch biopsy of the most prominent lesions should be performed and sent for histopathologic examination. (Choice A) The characteristic lesions and clinical presentation in this patient are not consistent with fungal infection, and microscopic examination with potassium hydroxide (KOH) preparation would be unhelpful. (Choice B) The diagnosis of LP requires a deep shave or punch biopsy of the skin lesions. Microscopic examination of skin scrapings in saline is not adequate. (Choice C) Patients with cutaneous sarcoidosis usually will have abnormalities on chest x-ray. However, LP has no pulmonary involvement, and chest radiographs have no role in this diagnostic evaluation. cutaneous sarcoidosis (Choice E) LP is not an infectious condition and consultation is not indicated at this time. Educational objective: Lichen planus is characterized by discrete, intensely pruritic, polygonal-shaped violaceous papules or plaques involving the flexural surfaces of the extremities (most commonly wrists), buccal mucosa, or external genitalia. A skin biopsy may be required to confirm the diagnosis. References: Lichen planus: an update and review. (http://www.ncbi.nlm.nih.gov/pubmed/22908728) Diagnosis and treatment of lichen planus. (http://www.ncbi.nlm.nih.gov/pubmed/21766756)

A 46-Year-Old Man Comes to the Physician's Office for a Pruritic