Follicular lymphoma of the stomach: immunohistochemical and molecular genetic studies.

The gastrointestinal (GI) tract is the most common site for the development of extranodal non-Hodgkin's lymphomas, with most cases having a diffuse architectural pattern. Follicular lymphoma (FL) of the stomach is a very rare disease, and little is known about the immuno-histochemical and molecular genetic characteristics of this type of lymphoma. Despite their rarity, FLs are an important consideration in the differential diagnosis of follicular hyperplasia of mucosa-associated lymphoid tissue (MALT), a relatively frequently encountered lesion with the potential to cause significant diagnostic difficulty, especially when assessment is based on scanty biopsy material. We report a 57-year-old woman with gastric FL, and describe the results of immunohistochemical and molecular genetic studies.