Clinical data and histologic material were retrospectively analyzed in 46 cases of previously untreated mantle cell lymphoma (MCL) to more fully characterize the clinical response pattern of these lymphomas and to determine whether growth pattern significantly affected clinical outcome.

The histologic pattern was classified as diffuse (61%), nodular (13%), and mantle zone (26%) in accordance with stated criteria.

Bone marrow infiltration was detected in 69% of cases; the frequency of involvement correlated with histologic pattern, being most common in diffuse variants and least common in mantle zone variants. Other sites of extranodal involvement were observed in 50% of cases. Cyclin-D1 staining revealed nuclear positivity in 23 of 25 patients (92%) and no difference was observed between the various histologic patterns. Rearrangement at the bcl-1 major translocation cluster (MTC) was detected in seven of 21 cases, without regard for histologic pattern. Complete response rates to doxorubicin-based regimens showed a striking correlation with histologic pattern. Seventy-three percent of patients with a mantle zone pattern attained a complete response compared with only 25% of patients with a nodular pattern and 19% with a diffuse pattern. Three-year survival rates were 100%, 50%, and 55% for patients with mantle zone, nodular, and diffuse histologic patterns, respectively.

We conclude that (1) diffuse and nodular MCL are associated with a poor treatment response and a poor overall survival rate; (2) the mantle zone variant exhibits the clinical attributes of a low-grade lymphoma; and (3) the poor survival rates of patients with nodular and diffuse MCL suggest that these variants be classified as intermediate-grade lymphomas. However, the trend of the time to treatment failure curve does not indicate that current regimens can cure MCL.