Highly infiltrative brain metastasis of RET mutant lung primary: Morphometric assessment and molecular review

Carcinoma and melanoma showed the largest cluster sizes of cells with an average cluster size of 238 ± 32 and 41 ± 5 cells, and DLBCL had an average of 3.2 ± 0.3 cells per cluster. When we compared extent of cell-to-cell coverage, DLBCL had the largest coverage with an average of 90 ± 8%, adenocarcinoma of the lung had 85 ± 7%, and melanoma had 55 ± 5%. The infiltrative features in this case are commonly seen in diffuse gliomas and are not characteristic of metastases. The molecular findings of co-mutation of <i>RET</i> and <i>TP53</i> suggest these could emerge as possible drivers of a more infiltrative growth pattern.