The laboratory and pathologist play an essential role in the diagnosis of hemophagocytic lymphohistiocytosis or HLH. The pathologist’s morphologic diagnosis as well as direction to appropriate additional testing are truly essential for patient care, explains Dr. Megan Nakashima in this CAPcast. Dr. Nakashima also helped developed a course on this topic as part of the CAP’s Clinical Laboratory Improvement Program, or CPIP: https://capatholo.gy/31JGonR.