The role of the gallium scan in primary extranodal lymphoma

The purpose of this study was to examine the factors influencing gallium scan positivity for patients with primary extranodal lymphoma and to examine the role of the gallium scan in staging the disease and assessing response to initial treatment.

Ninety-two patients with extranodal lymphoma who had a gallium scan were reviewed. The influences of tumor site, size, grade and the presence of clinically detectable disease after biopsy on the rate of gallium scan positivity were analyzed. The role of the gallium scan in staging and selecting treatment was assessed. Nineteen patients had a gallium scan to assess their response to treatment, and its predictive value was reviewed.

The overall gallium scan positivity (sensitivity) rate was 70%. This rate was low in patients whose extranodal lymphoma occurred in skin, intestine and testis, or was low grade (0%-25%). When these patients were excluded, the rate rose to 88%. Gallium scan positivity was not related to the presence of clinically detectable disease after biopsy and there was insufficient data about tumor size to determine a relationship. The gallium scan increased the disease stage in six patients (7%) and changed the initial treatment in six patients (7%). The gallium scan became negative in 15 (79%) of those patients who had a gallium scan to assess their response to treatment. All but two of these patients remain alive with a median follow-up of 3.75 yr.

The gallium scan was rarely positive for patients with skin, intestinal, testicular and low-grade lymphomas, but was otherwise comparable to lymphoma arising in lymph nodes. The result affected staging or treatment in seven patients (8%). After treatment, an initially-positive gallium scan usually became negative, a conversion associated with a favorable outcome.