World Health Organization and beyond: new aspects in the pathology of an old disease.

Hodgkin's lymphoma is a highly enigmatic lymphoma disease that still covers most of its secrets up to now. Much effort has been made to successfully wrest at least some of the pathogenetic particularities. The current diagnostic criteria are well established allowing hemato-pathologists to make a clear-cut distinction from other lymphomas in almost all cases. Although classic Hodgkin's lymphoma is curable in the vast majority of cases by treatment with highly aggressive drugs with or without radiotherapy, further molecular studies may lead to the identification of therapeutic targets that enable a more tailored treatment with fewer side effects.

Reed-Sternberg cell genome expression supports a B-cell lineage.

The malignant Reed-Sternberg cell of Hodgkin's disease, first described a century ago, has resisted in-depth analysis due to its extreme rarity in lymphomatous tissue. To directly study its genome-wide gene expression, approximately 11,000,000 bases (27,518 cDNA sequences) of expressed gene sequence was determined from living single Reed-Sternberg cells, Hodgkin's tissue, and cell lines. This approach increased the number of genes known to be expressed in Hodgkin's disease by 20-fold to 2,666 named genes. The data here indicate that Reed-Sternberg cells from both nodular sclerosing and lymphocyte predominant Hodgkin's disease were derived from an unusual B-cell lineage based on a comparison of their gene expression to approximately 40,000,000 bases (10(5) sequences) of expressed gene sequence from germinal center B cells (GCB) and dendritic cells. The data set of expressed genes, reported here and on the World Wide Web, forms a basis to understand the genes responsible for Hodgkin's disease and develop novel diagnostic markers and therapies. This study of the rare Reed-Sternberg cell, concealed in its heterogenous cellular context, also provides a formidable test case to advance the limit of analysis of differential gene expression to the single disease cell.

Follicular lymphomatoid papulosis.

A case of follicular lymphomatoid papulosis (LyP) is reported. The patient was a 60-year-old Japanese woman. Clinically, cutaneous eruptions were reddish, centrally depressed, dome-shaped papules on the extensor aspect of the forearm. Histologically, they exhibited features that fulfilled the disease criteria described by Pierard, et al., i.e., (Am J Dermatopathol 1980;2:173-80), mixed cellular infiltrates including atypical Reed-Sternberg cell-like type-A cells and mycosis cell-like type-B cells surrounding hyperplastic follicular epithelia. The patient also showed many typical nonfollicular LyP papules, i.e., rhythmically recurrent papules which underwent spontaneous involution within a few weeks, over a 10-year period. The coincidental occurrence of a rare variant of follicular LyP and typical LyP in the same individual further suggests that follicular LyP is merely a histological pattern of LyP involving epithelial adnexae.