According to the MP/H rules, what should not be counted when determining the number of primary tumors?

When determining the number of primary tumors according to the Multiple Primary and Histology (MP/H) rules, metastatic sites and microscopic tumor foci are both excluded.

Metastatic sites are considered secondary tumors, as they represent spread from a primary tumor rather than independent primary lesions. Therefore, they should not contribute to the count of primary tumors.

Microscopic tumor foci, which can occur in various contexts such as lymph nodes or other tissues, are generally classified as part of a single primary tumor if they are determined to be extensions or smaller satellite lesions rather than separate malignancies. Consequently, these foci are also not counted as separate primary tumors.

Thus, both metastatic sites and microscopic tumor foci do not denote distinct primary tumors in the context provided by the MP/H rules. This understanding leads to the conclusion that the correct answer encompasses both exclusions.