When A Patient Presents With Itchy Red Plaques In The Lower Extremities
A 25-year-old male who thought he had tinea pedis and corporis presented with red plaques extending from the medial aspect of his feet proximal into his lower extremities bilaterally. The patient had no pertinent past medical history, no medications and no history of dental work. The lesions were pruritic and he noticed when his cat scratched him, small marks remained on his legs that were also itchy. Due to this, he believed the skin disease was spreading and contagious.
He had been treating it with an over-the-counter topical antifungal for six months with no result. The patient also recently visited the dentist. At that time, he complained of canker sore-like lesions in his mouth. His dentist told him to stop chewing aspirin tablets but the patient denied ever doing so. He had a secondary complaint about his great toenails, noting that they were rough looking. The patient said he often wore closed-toe shoes to hide them.
During the physical exam, I noted small reddish plaques with a white scale that began at the medial ankle and continued up the leg into the thighs. The patient also had this distribution from the volar aspect of his wrists extending into his upper arm. No lesions were present on the trunk or the back. There were no vesicles, target lesions, purpura or ulcers. Bilateral hallux nails had trachyonychia at the proximal aspect of the nail plate. The patient’s fingernails were not affected at this time. There were no scalp lesions.
In the patient’s mouth, the left buccal mucosa had a small oval lesion, which was covered with white reticulated streaks.
The patient denied any further medical history and any current use of oral medications.
Key Questions To Consider
1. What are the characteristic skin lesions in this disease?
2. What is the most likely diagnosis?
3. What is your differential diagnosis?
4. What are the characteristic nail lesions in this disease?
5. What is the treatment?
Answering The Key Diagnostic Questions
1. The characteristics most associated with this skin condition are the P’s: plentiful, pruritic, polygonal, purple, planar, polished. Nails may appear rough and may have pterygium formation. Oral lesions with the characteristic Wickham’s striae may be present.
2. The most likely diagnosis is lichen planus, which has not only affected the skin but also the nails and the oral cavity.
3. Differential diagnoses include: psoriasis, tinea corporis, pityriasis rosea, lupus erythematosus, drug reaction, secondary syphilis and onychomycosis.
4. The characteristic nail deformity in this condition is the presence of nail plate thinning with longitudinal ridging, with or without pterygium.
5. Treatment varies and may include topical steroids, systemic steroids, systemic retinoids, or phototherapy depending on the severity of the presentation.
Pertinent Insights On Lichen Planus
This patient most likely has both the cutaneous and oral manifestations of lichen planus. Lichen planus is an idiopathic, T-cell mediated inflammatory condition that affects the skin, hair, nails and mucous membranes. The cutaneous form of lichen planus may affect up to 1 percent of the population in their 40s and 50s.1
There are numerous variations of lichen planus: atrophic, bullous, hypertrophic and ulcerative. The most common cutaneous presentation begins as a violaceous pruritic papule on the flexor surface of the wrists that erupts into similar papules spreading up the extremity.2 It also affects anterior aspects of the legs, neck and dorsum of the hands.
After the initial crop of lesions, a more widespread eruption of the lesions occurs after a week and one can describe this eruption as having the characteristic “P’s”: plentiful, polygonal, pruritic, purple, planar, polished papules and plaques. These lesions also have a flat top. The fine white lacy network sometimes visible on the surface of both the skin and oral lesions is called Wickham’s striae.