Inclusion Criteria:

• Male and female subjects 18 years of age and older.
• Have a primary diagnosis, or a high clinical suspicion, of cancer in the lung warranting surgery based on CT/PET or other imaging.
• Are scheduled to undergo surgical thoracoscopy for diagnostic wedge resection followed by anatomic lung resection.
• Female subjects of childbearing potential or less than 2 years postmenopausal agree to use an acceptable form of contraception from the time of signing informed consent until 30 days after study completion.
• Ability to understand the requirements of the study, provide written informed consent and authorization of use and disclosure of protected health information, and agree to abide by the study restrictions and to return for the required assessments .

Exclusion Criteria:

• Previous exposure to OTL38.
• Any medical condition that in the opinion of the investigators could potentially jeopardize the safety of the subject.
• History of anaphylactic reactions to folate, including synthetic folic acid (pteroylmonoglutamic acid) and contrast agents containing indocyanine green for near infrared imaging. Subjects with a medical history of 'idiopathic anaphylaxis' will require evaluation.
• History of allergy to any of the components of OTL38, including folic acid.
• A positive serum pregnancy test at Screening or a positive urine pregnancy test on the day of surgery or day of admission for female subjects of childbearing potential.
• Clinically significant abnormalities on electrocardiogram (ECG) at screening.
• Presence of any psychological, familial, sociological condition or geographical challenges potentially hampering compliance with the study protocol and follow-up schedule.
• Impaired renal function defined as eGFR < 50 mL/min/1.73m^2. Impaired liver function defined as values > 3 x the upper limit of normal (ULN) for alanine aminotransferase (ALT) or aspartate aminotransferase (AST), alkaline phosphatase (ALP), or > 2 x ULN for total bilirubin except in subjects with Gilbert's syndrome.
• Received an investigational agent in another investigational drug or vaccine trial within 30 days prior to the administration of study drug.
• Known sensitivity to fluorescent light.