Make the Diagnosis

Flat-topped papules on the neck, arms, and trunk

A 29-year-old male with no significant past medical history presented with a 3-month history of multiple 1-mm flat-topped papules on his neck, arms, and trunk. Some papules were grouped and some were arranged linearly. No oral lesions or nail involvement was present. A biopsy was performed on the shoulder.

Make the diagnosis:

Lichen planus

Lichen nitidus

Papular sarcoidosis

Papular eczema

Lichen nitidus (LN) is an uncommon inflammatory dermatosis of uncertain etiology. It most commonly presents as small, shiny, skin colored papules that typically occur on the trunk, extremities, or genitalia of children and young adults. However, it can affect people of all ages and all areas of skin. Lichen nitidus lesions may emerge in areas of trauma, often in a linear arrangement, called the Koebner phenomenon. It is not thought to be associated with any systemic disease. Nail involvement may be present. Oral lesions are not commonly seen. The diagnosis of LN is often a clinical one.

Histopathology for this patient showed a focally dense lymphohistiocytic infiltrate with multinucleate giant cells in the papillary dermis, associated with overlying epidermal atrophy and adjacent elongated rete ridges surrounding the infiltrate in a characteristic “ball and claw” pattern. These findings were consistent with a diagnosis of lichen nitidus.

The differential diagnosis includes lichen planus (LP). In LP, lesions tend to be larger and more violaceous. They tend to favor wrists, lower extremities, and genitalia. Oral and nail involvement are common. Histologically, a band-like lichenoid infiltrate in the dermis is present. Granulomatous inflammation and giant cells are absent. Direct immunofluorescence is positive for globular deposits of IgG, IgA, IgM and/or complement at the dermal-epidermal junction.

A hepatitis panel was drawn for this patient and was negative. Treatment for lichen nitidus is only needed if symptomatic because lesions will generally resolve spontaneously. Lesions may take months or years to resolve. For significant pruritus, topical corticosteroids or antihistamines may be used. Topical emollients are recommended. Topical tacrolimus has been reported to improve lesions. Oral steroids and light therapy have been reported to improve generalized lichen nitidus not responding to topical treatments.

Dr. Donna Bilu Martin

The case and these photos were submitted byMs. Swartz of Nova Southeastern University, Ft. Lauderdale, Fla.; Dr. Chen and Dr. Walder of Bay Harbor Islands, Fla.; and Dr. Winslow of Pompano Beach, Fla. Donna Bilu Martin, MD, editor of this column, is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at MDedge.com/Dermatology. To submit a case for possible publication, send an email to [email protected].

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