Localized lymphomatoid papulosis.

A 50-year-old Japanese male visited our clinic in April 1999 with a 2-year history of self-healing, reddish papules on his right palm. On examination, there were grouped erythematous papules, 2-4 mm in size, which formed a relatively well-circumscribed erythematous plaque. A biopsy specimen showed a wedge-shaped, dense dermal infiltrate consisting of variously sized mononuclear lymphoid cells mixed with few large CD30-positive cells and inflammatory cells, suggesting the diagnosis of regional lymphomatoid papulosis (LyP). Analysis of the T cell receptor gene revealed a polyclonal pattern on lesional skin. Only 5 cases of LyP presenting in a regional distribution have been reported previously. Although the etiology of localized LyP remains unknown, considering that 2 of 5 reported patients developed widespread lesions regional LyP may be the initial presentation of typical LyP.