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A Pruritic, Polygonal, Papular, Rash on a 10-year-old Boy

A Pruritic, Polygonal, Papular, Rash on a 10-year-old Boy

  • The Tale of a Male with a Pruritic, Polygonal, Papular, Planar Rash

  • The afternoon's first case in the acute care clinic promised to be "real challenge" to your dermatology skills.

  • A 10-year-old boy with past history of nummular eczema presents with 2-week history of rash that progressed from erythematous planar papules to larger polygonal, violaceous plaques that were purple and pruritic.

  • Mother denies any oral medications, history of contact exposures. Immunizations are up-to-date, medical history is “normal.”

  • Purple, polygonal papules and plaques.

  • Close-up of purple, polygonal papules and plaques.

  • Pruritic purple, polygonal, planar papules and plaques.

  • Papules, plaques are also seen on the penis.

  • Oral cavity showing a white, lacey pattern on the buccal mucosa.

  • Differential diagnosis for pruritic, purple popular rash: Guttate psoriasis, lichen planus, lichen nitidus, pityriasis rosea, tinea corporis, plaque psoriasis, lichen simplex chronicus.

  • Diagnosis: Lichen planus.

  • The 6 Ps of lichen planus: purple, polygonal, pruritic, planar, papules, plaques – sometimes including the penis.

  • Lichen planus: chronic inflammatory cell-mediated immune response of unknown origin. It may be found with other diseases of altered immunity.

  • Lichen planus overview: affects skin, oral and genital mucosa, scalp, nails. Acute onset; lesions covered by Wickham striae; scalp lesions can progress to scarring alopecia.

  • Lichen planus: clinical diagnosis; biopsy useful in atypical presentations; “saw-tooth” epidermal hyperplasia; hyperparakeratosks, T-cell infiltration at dermal-epidermal junction.

  • May cause lichen planus-like eruptions: arsenic, gold, PAS, isoniazid, quinidine, streptomycin, diabinase, phenothiazides, salts in color film.

  • Lichen planus: usually self-limited; typically resolves within 8-12 months. Treat mild cases with fluorinated topical steroids.

  • Lichen planus: seen infrquently in primary care practice; consult with dermatology is recommended.

It's after lunch in the acute care clinic and your nurse opens the afternoon by telling you that a difficult dermatology case awaits. You're no stranger to this kind of challenge and enter the exam room with great confidence.

The patient: a 10-year-old boy with a history of numular eczema and a recent 2-week history of a widespread rash. Follow the case and its clues in the slides above. You may need to draw on your memory of medical school Derm 101 to generate your diagnosis.


hypersensitivity response

Romilla @

Lichen Planus

Arif Ahamed @

For Jerry and others. Listed are superb downloadable pdf review article that will increase your knowledge of lichenoid diseases in children: YOU WILL see many of these in your practices!

I have pictures of virtually every condition and I hope to share these in the future. They are essential for us to know as we are the frontline docs and in knowing these we save our parents/ patients unnecessary consultations and inappropriate therapy. I have an entire lecture series entitled "Some Rashes I Would Be Lichen to Share with You."

Jon Schneider PGY 42.5, author

Jonathan @

Actually, a very informative and succinct presentation for those of us who are dermatologically-challenged. I would have liked a bit more about how to distinguish it from the top 3 or 4 diagnoses in the differential.

Jerry @

Thanks for your response, Jerry. I,will not cop out. First, though, all my cases are wonderfully edited by another,m person who is absolutely marvelous. She challenges me to keep my cases "short and sweet." That means that sometimes the best I can do is whet your appetite to read further. As a resident that was the way I was taught. The correct diagnosis was nice, but it was up to me to learn the differential diagnosis. In dermatology, especially, it greatly expanded my horizons to do so. In practice, My residents were often given a "prescription for learning" at the end of the day. We would agree to look up something we saw that day and discuss it the next day. While I did mention that the diseases in the differential would offer other symptoms, the question remains as you asked. I promise to research this out if you will, too. The question is: "what diseases mimic lichen planus?"

Jonathan @


Cesar V @

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