Malignant lymphoma involving the prostate: report of 62 cases.

BACKGROUND

Malignant lymphoma involving the prostate is rare, and to the authors' knowledge the factors determining patient outcome have not been studied in a large series.

METHODS

The authors evaluated the clinical and pathologic findings in 60 cases of non-Hodgkin's lymphoma and 2 cases of Hodgkin's lymphoma involving the prostate. A variety of clinical and histologic findings were considered as factors predictive of patient outcome.

RESULTS

Lymphoma tended to occur in elderly men, with a mean age at diagnosis of 62 years (range, 5-89 years), although 6 patients were age < 40 years (ages 5, 19, 30, 32, 38, and 38 years, respectively). Clinical signs and symptoms were due to lower urinary tract obstruction. Twenty-two patients (35%) presented with primary extranodal lymphoma of the prostate with a variety of histologic subtypes, including small lymphocytic (4 patients); follicular center cell, diffuse, small cell (2 patients); follicular center cell, Grade 1 (according to the revised European-American classification (small cleaved) (1 patient); Grade 2 (mixed) (1 patient); diffuse large B-cell (12 patients); and high grade B-cell lymphoma, Burkitt-like (2 patients). At the time of presentation, none of these patients had hepatosplenomegaly, inguinal lymphadenopathy, or an abnormal complete blood count. Thirty other patients (48%) with previously documented lymphoma at other sites developed prostatic involvement; these secondary prostatic lymphomas displayed a variety of subtypes, including small lymphocytic (8 patients, all with concomitant leukemia); follicular center cell lymphoma, diffuse, small cell (2 patients); follicular center, Grade 1 (small cell) (1 patient); follicular center, Grade 2 (1 patient); diffuse large B-cell (11 patients); peripheral T-cell lymphoma (2 patients); high grade B-cell lymphoma, Burkitt-like (1 patient); Burkitt's lymphoma (1 patient); Hodgkin's lymphoma (nodular sclerosing [1 patient] and mixed cellularity [1 patient]); and unknown (1 patient). Ten cases were not classifiable as primary or secondary lymphomas. Twenty-five patients died of malignant lymphoma, 14 died of unknown or other causes, 18 patients were alive 12-20 months after diagnosis (8 primary and 10 secondary tumors; 3 had persistent lymphoma; all treated since 1981), and 5 were lost to follow-up. Lymphoma specific survival was 64% at 1 year (95% confidence interval [CI], 51-80%), 50% at 2 years (95% CI, 36-68%), 33% at 5 years, 33% at 10 years, and 16% at 15 years. There was no difference in median survival after diagnosis of prostatic involvement between primary and secondary lymphoma (23 months vs. 28 months, respectively) or among histologic types.

CONCLUSIONS

Although malignant lymphoma involving the prostate is rare, it should be considered in the differential diagnosis of lower urinary tract obstruction, particularly in patients with a previous history of lymphoma.