Over the years many amazing cases have been presented during the PEMPix presentation at the American Academy of Pediatrics’ annual national Conference and Exhibition during the Section on Emergency Medicine Sessions. PEMPix Classic is a new featured series on PEMBlog that will highlight some of those classic cases.

The Case

A twelve-year old African-American male with no significant past medical history who presents with a two month history of a rash to his right arm. It started at the elbow and progressed up the arm towards the axilla. The patient denied any trauma, new contacts, change in daily routine (soaps, detergents, lotions, etc,.). He had seen his pediatrician on three occasions over the two month period and completed courses of Trimethoprim/Sulfamethoxazole and Cephalexin for a presumed soft tissue infection and a course of topical Clotrimazole with no improvement. 

This is a linear rash extending up the arm; papular, coarse, and flesh colored. There was no surrounding erythema. It is also painless, non-pruritic, and not warm to touch.

What is the diagnosis?

A. Contact Dermatitis
B. Plaque Psoriasis
C. Lichen Striatus
D. Hookworm
E. Tinea Corporis


C. Lichen striatus

Lichen stratus is an uncommon, benign self limited linear inflammatory skin disorder. Most commonly seen in children around 2-3 years of age. It is known to encounter in teens as well. Girls are more commonly affected than boys. Lichen striatus may be the result of an abnormal immunologic reaction or genetic predisposition that is precipitated by some trigger such as a viral infection, trauma, hypersensitivity reaction, vaccine administration, seasonal variation, medication, or pregnancy. In this case, a Staphylococcal infection may have been the predisposing factor.

It typically presents with the sudden eruption of asymptomatic small, flat-topped, lichenoid, scaly papules in a linear array. Multiple lesions develop and then merge into linear plaques along the lines of Blaschko. They are usually asymptomatic but may be pruritic. Treatment is typically not indicated but may include topical steroids, topical retinoids, or topical calcineurin inhibitors. Most cases resolve within one year and reoccurrence is rare.


Shiohara T, Kano Y. Lichen planus and lichenoid dermatoses. In: Bolognia J, Jorizzo J, Schaffer J, eds. Dermatology.3rd ed. Philadelphia, PA: Elsevier/Saunders; 2012:183-202.

Wang WL, Lazar A. Lichenoidand interface dermatitis. In: Calonje E, Brenn T, Lazar A, et al, eds. McKee’s Pathology of the Skin. 4th ed. London, England: Elsevier/Saunders; 2011:219-258.