 4. Continued from No. 3: The diagnostic criteria that have been traditionally used for children HLH 1991 and HLH 2004 may not adequately diagnose HLH in adults. This is the first adult HLH protocol in the country. In the absence of standard diagnostic guidelines if the patients symptoms are highly suspicious for HLH and after an adequate work-up to rule out alternate potential alternate etiologies is performed we will treat the patient for HLH as missing the diagnosis is associated with high mortality. These patients will be discussed with the PI Dr Daver prior to enrollment in all such cases. 