ABSTRACT
The appearance of distant metastases after five or more years is not rare in some cancers, particularly breast and genital tumors and melanomas. This phenomenon is referred to as tumor dormancy. In deciding whether to call a particular tumor cancerous, the pathologist has generally relied on this definition. The changes in histologic appearance such as increased mitotic rate, increased nuclear cytoplasmic ratio, prominent nucleoli, increased DNA staining, irregular nuclear membrane, necrosis, and when possible, invasion. The problem of dormancy certainly involves the immune system. The primary tumor is not always so evident. Careful examination may show a scar in the skin where a lesion was fulgurated years earlier. The number increased when cases of leukemia, lymphoma, and squamous cell carcinoma were added. Thirteen Neuroblastomas were the most frequently observed tumors that regressed spontaneously. The host response to the tumor may be marked by infiltration of the tumor by lymphocytes, plasma cells, and fibroblasts.
