A 64-year-old male (Patient B) with a heterozygous germline-ATM mutation (c.2413C>T (p.Arg805*)) and remote history of right-sided breast cancer and synchronous bilateral non-small cell lung cancers (NSCLC) presented after numerous, bilateral supra- and infratentorial brain lesions were noted on surveillance imaging for a known, stable right vestibular schwannoma. The gene discussed is ATM; the disease is breast carcinoma.