The "hot spleen" phenomenon in metastatic malignant melanoma: its incidence and relationship with the immune system.

Of patients with Stage II and III malignant melanoma, 34.7% display reversal of the liver-spleen ratio on technetium-99m-sulphur colloid isotope scans. Such an occurrence does not suggest a greater likelihood of relapse or a worse survival. The phenomenom is more common in female patients and there is a significant relationship between the presence of a "hot spleen" and a high IgM level. Patients with Stage II disease and high IgM levels have relapses more quickly than do those with normal IgM levels. Lymphopenia is common in patients with Stage II and III disease and the survival of these patients is worse than that of those with normal lymphocyte counts. In this report, the data are discussed together with results from other investigations, and a unifying hypothesis is presented which explains the phenomenon and relates it to increased activity of macrophages as a result of the presence of the tumor. The usefulness of isotope liver scanning in stage III malignant melanoma is also discussed.