Neurofibromatosis type 1 is a genetic condition that can cause tumors to form on nerves under the skin. Since these tumors can become malignant, it is important to monitor their growth closely and detect signs of malignant transformation as early as possible. However, the only way to currently detect them is with an MRI scan. New research published in BioMed Central’s open access journal BMC Medicine shows that a simple blood test for the protein melanoma-inhibitory activity (MIA) may be used to indicate the presence of neurofibromas even if they cannot be seen [1].