Selumetinib Sulfate in Treating Patients With Relapsed or Refractory Advanced Solid Tumors, Non-Hodgkin Lymphoma, or Histiocytic Disorders With Activating MAPK Pathway Mutations (A Pediatric MATCH Treatment Trial)

Inclusion Criteria: * Patient must have enrolled onto APEC1621SC and must have been given a treatment assignment to molecular analysis for therapy choice (MATCH) to APEC1621E based on the presence of an actionable mutation * Note: patients with BRAF V600 actionable mutations of interest (aMOIs) will be preferentially assigned to APEC1621G (vemurafenib) if that study is open and they are otherwise eligible for it * Patients must have a body surface area \>= 0.5 m\^2 at enrollment * Patients must have radiographically measurable disease at the time of study enrollment; patients with neuroblastoma who do not have measurable disease but have iobenguane (MIBG) positive (+) evaluable disease are eligible; measurable disease in patients with CNS involvement is defined as tumor that is measurable in two perpendicular diameters on magnetic resonance imaging (MRI) and visible on more than one slice * Note: the following do not qualify as measurable disease: * Malignant fluid collections (e.g., ascites, pleural effusions) * Bone marrow infiltration except that detected by MIBG scan for neuroblastoma * Lesions only detected by nuclear medicine studies (e.g., bone, gallium or positron emission tomography \[PET\] scans) except as noted for neuroblastoma * Elevated tumor markers in plasma or cerebrospinal fluid (CSF) * Previously radiated lesions that have not demonstrated clear progression post radiation * Leptomeningeal lesions that do not meet the measurem…