Primary cutaneous medium and large cell lymphomas (MLCL) other than mycosis fungoides (MF) are rare, and their prognosis and treatment are controversial. The clinical, immunohistological and follow-up data of 54 well-documented cases of primary cutaneous MLCL other than MF, seen in our institutions over a 14-year period, were retrospectively reviewed, in order to determine the prognostic factors related to these lymphomas, and to analyse the results obtained with different treatment regimens. Forty-six patients presented with a solitary tumour or with localized lesions, and eight had disseminated cutaneous lesions. According to the updated Kiel classification, 45 cases (83%) corresponded to B-cell lymphomas: centroblastic lymphomas, 32 cases; centroblastic-centrocytic lymphomas, 11 cases; immunoblastic lymphomas, two cases. Nine cases (17%) were classified as T-cell lymphomas: pleomorphic medium and large cell lymphomas, eight cases; anaplastic large cell lymphoma, one case. Four of eight patients with disseminated skin lesions had a T-cell lymphoma, whereas 41 of 46 patients with a solitary tumour had a B-cell lymphoma. Patients with disseminated skin lesions and elevated serum lactate dehydrogenase (LDH) levels had a poor prognosis. Comparison of patients' overall survival, depending on immunohistological subtype, showed that the median survival of patients with pleomorphic T-cell lymphoma was 2.5 years, whereas it was not reached at 12 years for patients with centroblastic-centrocytic and centroblastic lymphoma. The eight patients with disseminated skin lesions were treated with polychemotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)