It is, rather, a response to a variety of known and unknown stimuli that results in the accumulation of lymphocytes and other inflammatory cells within a localized region. It is infamous for simulating lymphoma, primarily histologically, but sometimes clinically. When known, the inciting agent should be included within the diagnosis. The term lymphocytoma cutis or pseudolymphoma without modification should be reserved for idiopathic cases. In lymphocytoma cutis, lymphocytes and other inflammatory cells are recruited to a localized area of the skin in response to known or unknown stimuli.
Most cases are idiopathic.
A discrete subset of lymphocytoma cutis, borrellial lymphocytoma, is seen primarily in Europe, in areas endemic for the tick Ixodes ricinus. It is a response to infection by Borrelia burgdorferi subsp afzelius conferred by tick bite. Lymphocytoma cutis is not associated with mortality. It is rarely associated with morbidity other than minor pain or pruritus. No racial predilection has been noted.