Viral infection, atopy and mycosis fungoides: a European multicentre case-control study.

Mycosis fungoides (MF) is a rare disease with an unknown aetiology, although it has been suggested that infections may play a role. The present study investigates whether infections, atopic disorders and some other diseases are risk indicators for MF. A European multicentre case-control study involving seven rare cancers, including MF, was conducted from 1995 to 1998. Patients between 35 and 69 years of age diagnosed with MF (n = 140) were recruited, and the diagnoses were verified by a reference pathologist, who classified 83 cases as definitive and 35 cases as possible; 22 cases were not accepted. Of the 118 accepted cases, 104 patients were interviewed (including 76 definitive cases and 28 possible cases). These 76 definitive cases were used for this study. A common set of controls to serve all case groups were interviewed, representing a total of 4574 controls. The latter included 1008 colon cancer patients and 3566 subjects selected from population registers. Information on infections, skin pathology and clinical history 5 years before the diagnosis of MF was used to estimate odds ratios (ORs) derived from logistic regression-modelling, which included gender, age and country. The highest ORs for MF were found in patients who reported a history of psoriasis 5 years before MF was diagnosed (OR 7.2, 95% CI: 3.6-14.5). Urticaria had an OR of 1.4 (95% CI: 0.6-3.6). Infections and atopic diseases were not closely associated with MF. Some diseases correlated to MF. Whether this has a causal background or reflects early diagnostic uncertainty is not known.