Although blood biomarkers can be used to directly measure CSF1R involvement in certain diseases, such as lymphoma [11], methods of determining CSF1R involvement and quantifying CSF1R levels at loci not directly connected to the central circulatory system is difficult, particularly in the CNS, and employs either indirect means (i.e., measurement of CSF1 levels as a proxy for CSF1R [14]) or invasive procedures (i.e., immunohistochemistry using a biopsy sample or surgically excised tissue [15,16]). The gene discussed is CSF1R; the disease is lymphoma.