Evidence for the formation of metaplastic bone from pericytes in calcifying fibroblastic granuloma.
BACKGROUND
The calcifying fibroblastic granuloma (CFG) is a variant of epulis characterised histologically by calcified nodules and metaplastic bone formation and clinically by its pattern of frequent recurrence. Recent evidence suggests that calcified nodules and bone may form directly from non-haemopoetic pericytes in a variety of situations. This study aimed to test the hypothesis that metaplastic bone formation in CFG may be the result of a pericytic differentiation pathway.


METHODS
A series of 16 cases of CFG meeting the criteria of Lee were reviewed and stained using markers which aid the identification of pericyte (smooth muscle actin, von Willebrand's factor, monoclonal antibody 3G5) and osteoblast (AML-3) lineages.


RESULTS
The cells in mineralising areas of CFG resembled pericytes morphologically. Often, calcified nodules were observed within the vascular basement membrane and nodules frequently formed the nidus for reactive bone formation. The pericyte-like cells were positive for smooth muscle actin and AML-3 and were negative for von Willebrand's factor.


CONCLUSIONS
These data provide circumstantial evidence for a pericytic lineage in CFG.
Dayoub
S
S
Dental School, Damascus University, Syria.
Devlin
H
H
Sloan
P
P
D000199:Actins / Q000032:analysis; D000911:Antibodies, Monoclonal; D001485:Basement Membrane / Q000473:pathology; D015415:Biomarkers / Q000032:analysis; D001842:Bone and Bones / Q000473:pathology*; D002114:Calcinosis / Q000473:pathology*; D002454:Cell Differentiation; D019070:Cell Lineage; D005347:Fibroblasts / Q000473:pathology; D005732:Gangliosides / Q000032:analysis; D005882:Gingival Diseases / Q000473:pathology*; D006099:Granuloma / Q000473:pathology*; D006801:Humans; D008679:Metaplasia; D009131:Muscle, Smooth, Vascular / Q000473:pathology; D010006:Osteoblasts / Q000473:pathology; D020286:Pericytes / Q000473:pathology*; D014841:von Willebrand Factor / Q000032:analysis
D000199:Actins; D000911:Antibodies, Monoclonal; D015415:Biomarkers; D005732:Gangliosides; D014841:von Willebrand Factor