ABSTRACT
BACKGROUND: While a dermal proliferation of monotypic monoclonal lymphocytes and plasma cells suggests above all cutaneous marginal zone lymphoma (CMZL) or plasmacytoma, it may also correspond to a Borrelia infection of which the clinic picture is evocative, as demonstrated in the cases presented herein. PATIENTS AND METHODS: The files of two patients were submitted for discussion at the regional multidisciplinary staff meeting on cutaneous lymphomas after review of the skin biopsies led to a diagnosis of plasmacytoma and CMZL on the basis of infiltrate containing abundant plasma cells. The infiltrates of both patients showed a kappa monotypic light chain and cutaneous B-cell clones were detected. However, the clinical features, with monomelic maculopapular rash, were evocative primarily of Borrelia infection. Diagnosis was confirmed by positive serology and clinical cure was achieved after 3 weeks of oral tetracycline, without relapse. COMMENTS: A link between Borrelia infection and cutaneous lymphomas has long been thought to exist. Further, it is recommended that antibiotics be considered in CMZL before undertaking systemic therapy. The classic histological appearance of the tertiary phase of early-stage Lyme's disease shows perivascular and periadnexal infiltrate comprising lymphocytes and plasma cells. At the later stages, epidermal atrophy occurs with thinning of the dermis. The monoclonal and monotypic nature of skin proliferation points above all to CMZL or plasmacytoma. However, clinicopathological correlation is an essential step before such a diagnosis may be made. In the event of monomelic erythema, as in our patients, it is important to screen for Borrelia infection, which responds well to appropriate treatment.