Exploring the causes of cutaneous B-cell lymphoma: We should learn from the Lyme disease experience

Epidemiological studies rely on the uneven distribution of disease within a nd between populations and represent a simple but efficient way of studying disease causation. The incidence of non-Hodgkin's lymphomas (NHLs) has inc reased dramatically over the past few decades and the epidemic calls for ep idemiological studies. The study of Munksgaard and colleagues, in this issu e of Dermatology, is a good example of an epidemiological study based on th e so-called ecological correlation. It focuses on cutaneous B-cell lymphoma (CBCL) and fails to document a correlation between CBCL incidence and Lyme disease as a surrogate indicator for the exposure to tick bites. Although ecological studies neither inform about the time relationship between expos ure and disease nor usually allow control for confounding variables, they c an provide important information that would guide the direction of further research. There is a number of analytical studies focusing on risk factors for NHLs. One drawback of these studies is that they consider NHLs as a sin gle category. One merit of the paper of Munksgaard et at. is that it focuse d on a rather specific disease, i.e. CBCL. Copyright (C) 2000 S. Karger AG, Basel.