Lymphomatoid papulosis (LyP) is a chronic papulonecrotic or papulonodular skin disease with histologic features suggestive of a malignant lymphoma. The disease is characterized by recurrent crops of pruritic papules at different stages of development that predominantly arise on the trunk and limbs. The papules heal spontaneously over 1-2 months, usually leaving slightly depressed oval scars.
This crazy condition has been variously described as a pseudolymphoma, a variant of lymphoma of the indolent T Cell variety, or as a paraneoplastic condition. Its character, however, is not so much neoplastic as a benign clinical variant.
The condition, as above, comes as both a papulonecrotic and papulonodular variant, and although I have seen both, in my limited experience the papulonecrotic variant is far more common.
It is imperative that this is a histopathologic diagnosis, with gene rearrangement studies performed to ensure that this does not represent a clonal condition, which would represent a cutaneous T cell lymphoma.