biphasic disease biphasic disease a biphasic disease is a disease which has two distinct phases or components. in clinically biphasic diseases, the phases are generally chronologically separated. in histopathologically biphasic tumors (also called biplastic tumors), there is neoplastic tissue which contains two different cellular elements. examples clinically biphasic diseases diseasetypical first phasetypical second phase european (or "western") subtype of tick-borne encephalitis virus relatively mild flu-like illnessaffecting some cases, generally presenting with high fever and neurologic disease (encephalitis), meningitis and/or meningoencephalitis) leptospirosis 4–9 days of abrupt onset of flu-like illnessfever, jaundice, abdominal pain and diarrhoea. organ failure in severe cases. anthrax after approximately 4 days, patients develop flu-like illness with fever, nonproductive cough, and myalgias lasting approximately 4 dayswithout timely treatment, a second fulminant phase follows, characterized by hypotension and dyspnea. this phase may progress to death within 24 hours of its onset tumor biplasia main article: mixed tumor diseasecellular elements fibroadenoma epitheliumstroma ceruminous adenoma inner luminal secretory cellsmyoepithelial cells