Three types of intracytoplasmic inclusions immunoreactive to
fibrinogen are collectively diagnosed as hepatic
fibrinogen storage disease. This study aimed to better characterize ground glass (type II) and globular (type III)
fibrinogen inclusions by the pathological examination of 3 cases and a literature review. Three adults (age: 32-64 years; male/female = 2:1) were unexpectedly found to have
fibrinogen-positive ground glass changes (type II inclusions) by liver needle biopsy, against a background of acute
hepatitis E, resolving acute
cholangitis, or severe lobular
hepatitis of unknown etiology. One patient also had
fibrinogen-positive intracytoplasmic globules (type III inclusions) in the first biopsy, but they were not present in a second biopsy. None had coagulation abnormalities or hypofibrinogenemia. On immunostaining, both inclusions were strongly positive for not only
fibrinogen but also
C-reactive protein and C4d. Ultrastructurally, ground glass changes corresponded to membrane-bound cytoplasmic inclusions containing amorphous, granular material. The pathological features of type II
fibrinogen inclusions were identical to those of pale bodies in
hepatocellular carcinoma. The literature review suggested that type I
fibrinogen inclusions characterized by a polygonal appearance are strongly associated with mutations in
fibrinogen genes, coagulopathy, and family history, whereas type II/III inclusions are immunoreactive to multiple
proteins and typically develop in cases of other unrelated
liver diseases. In conclusion, type II and III
fibrinogen inclusions do not represent a true hereditary storage disease but instead the collective retention of multiple
proteins. Given the lack of clinical significance, a less specific name (e.g., pale body) may be more appropriate for those inclusions.