This phase III trial studies how well pafolacianine works for identifying cancerous lesions in children and adolescent patients with primary solid tumors or solid tumors that have spread from where they first started (primary site) to other places in the body (metastatic). Pafolacianine is a fluorescent imaging agent that targets folate receptors which are overexpressed in many cancers and is used with near infrared (NIR) imaging during surgery to identify tumor cells. NIR uses a special camera that uses wavelengths in the infrared range to visualize and locate the tumor cells that are lit up by the pafolacianine. Giving pafolacianine for NIR imaging may work better than other imaging agents in identifying cancerous lesions in pediatric patients with solid tumors.

Inclusion Criteria:

• Willingness of research participant or legal guardian/representative to give written informed consent
• Age 6 months to 17 years
• Have a diagnosis, or a high clinical suspicion, of a solid tumor in the neck, chest, abdomen, pelvis, or extremities with a plan for surgical resection including embryonal tumors, sarcomas, neurogenic tumors, carcinomas, mesenchymal tumors, germ cell tumors. Children may undergo surgical resection or biopsy of a solid tumor that is suspected to be malignant without a separate preoperative biopsy; therefore, the tumor type may not be definitively known preoperatively

Exclusion Criteria:

• Previous exposure to Cytalux™ (pafolacianine) injection
• Any medical condition that in the judgement of the investigators could potentially jeopardize the safety of the participant
• History of anaphylactic reactions to products containing indocyanine green for near infrared imaging. Participants with a medical history of 'idiopathic anaphylaxis' will require evaluation
• History of allergy to any of the components of Cytalux™ (pafolacianine) injection
• Presence of any psychological, familial, sociological condition or geographical challenges potentially hampering compliance with the study protocol or follow-up schedule
• Received an investigational agent in another investigational drug or vaccine trial within 30 days prior to the administration of the study drug. Investigational trials involving administration of drugs or vaccines which are already Food and Drug Administration (FDA)-approved, such as Children's Oncology Group cooperative trials, are okay
• Known sensitivity to fluorescent light
• Pregnancy
• Unable or unwilling to discontinue folic acid, folate supplements, and multi-vitamins containing folate 48 hours prior to drug administration
• Renal failure on dialysis or estimated glomerular filtration rate (eGFR) < 30 mL/min/1.72m^2 as measured by the U25 eGFR equation for patients ≥1 year(s) of age. For patients < 1 year of age, creatinine > 2x the upper limit of normal will serve as an exclusion criteria. Creatinine will be measured by enzymatic assay with calibration traceable to the international standard reference materials and minimal bias compared to isotope-dilution mass spectrometry (IDMS) reference methodology.
• Undergoing workup for liver failure or listed for liver transplant. Patients with Gilbert's syndrome will be excluded if impaired liver function defined as values > 3x the upper limit of normal (ULN) for alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), or total bilirubin
• Unable or unwilling to use adequate birth control/contraceptive measures or abstain from sexual activity for 30 days following the study intervention
• Anticipated need to donate ova or sperm within 30 days following study intervention