The morphologic, immunophenotypic, and clinical characteristics of 20 cases of primary cutaneous large cell lymphoma were analyzed. Immunoperoxidase stains in paraffin sections indicated B-cell phenotype in 14 cases and T-cell phenotype in six cases. By the Kiel classification, the B-cell lymphomas were classified into the following categories: follicular centroblastic (three patients), centroblastic/centrocytic with a predominance of large centrocytes (two patients), centroblastic (seven patients), and immunoblastic (two patients). The T-cell lymphomas (six cases) were all categorized as pleomorphic medium and large cell type. Three of these had an angiocentric growth pattern. The lymphocyte activation marker CD30 was expressed in three of the 20 cases. Among these 20 patients, the clinical course was remarkably variable. The only clinical or pathologic feature with prognostic significance was multicentricity of the skin lesions. All five patients with multifocal or disseminated skin lesions died within 13 months of their initial presentation; the median survival was 7 months. Most of the patients with localized skin lesions had an indolent clinical course with a median survival of 107 months. These results suggest that multicentricity of the skin lesions and necrosis are closely linked and are important prognostic features in cutaneous large cell lymphoma.