Follicular lymphoma in Osaka, Japan: histological features and chronological change.

Follicular lymphoma (FL) is defined as a neoplastic proliferation of follicle center cells with varying follicular areas. To learn the time trend of FL in the Osaka area, an adult T-cell leukemia/lymphoma (ATL) nonendemic area of Japan, we examined the frequency of FL among all non-Hodgkin's lymphomas (NHLs) during the period 1964 to 1987 (n = 1,000) and 1999 to 2001 (n = 659). The frequency of FL with varying follicular areas increased from 1964-1987 to 1999-2001. There was a significant difference in frequency of total cases of FL (14.2% versus 18.8%) (P < .05) and FL with no to 25% follicular area (2.3% versus 5.0%) (P < .01). According to the Berard criteria, cytologic grade of FL was defined by counting the number of centroblasts (CB) in 10 neoplastic follicles as follow: < or = 5 CB per high power field (HPF), grade 1; 6-15 CB, grade 2; >15 CB, grade 3. Immunohistochemical staining with monoclonal antibodies for bcl-2 and CD10 was performed. There was an inverse correlation between follicular area and cytological grade (P < .0001) and bcl-2 expression and cytological grade (P < .01). That is, the larger the follicular area in cases with a lower cytological grade, the stronger was bcl-2 expression in a lower cytological grade. There was a significant correlation between follicular area and stage of disease (P < .05). That is, the follicular area was larger in cases in an advanced stage. This study showed the increase in frequency of FL in Osaka, Japan. Change of lifestyle in Japan may be one of the causative factors for the increase.

Clonality analysis of follicular lymphoma using laser capture microdissection method.

Whether a common and a single clone present, or not, among follicles of follicular lymphoma (FL) was examined in 12 cases with FL. Histologic grade was I in 6 cases, II in 3, and III in 3. DNA was selectively extracted from the neoplastic follicles of paraffin-embedded samples with use of laser capture microdissection method, and used for PCR-based analysis of rearrangement of immunoglobulin heavy chain variable region gene. Three different follicles in each case of FL were microdissected. Semi-nested PCR was performed using two sets of primers (Fr2A and Fr3A). In PCR with Fr2A primers, nine of 12 cases showed a common band among neoplastic follicles. The remaining three cases showed no PCR products. With Fr3A primers, eight of 12 cases showed a common band among follicles of the same case. The other four cases showed oligoclonal bands, among them presence of a common band was difficult to assess. Oligoclonal bands were more frequently observed in PCR with Fr3A than that with Fr2A and in grade I or II than in grade III cases. In total, 11 of 12 cases showed a common band in PCR with either Fr2A or Fr3A primers. In two cases, DNA extracted from whole section was amplified with both Fr2A and Fr3A or only Fr3A primers, showing smear or oligoclonal bands. These results showed the presence of a single clone of cells in neoplastic follicles of FL and the usefulness of PCR-based rearrangement analysis of immunoglobulin heavy chain gene combined with microdissection methods for differential diagnosis of FL from follicular hyperplasia.