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a 51 year old female had a central giant cell lesion removed from her mandible 12 years before presentation but unfortunately the old records were not available for reference .
she was referred by her dentist to our oral and maxillofacial surgery unit for possible recurrence of the lesion .
the patient was asymptomatic apart from slight altered sensations in her left lower lip and chin which has been there since her operation 12 years previously .
orthopantomogram showed an irregular well defined 4.5  cm    2.5  cm radiolucency extending from the lower left second premolar to the lower right canine roots ( fig .
the roots of the lower left canine , first and second premolars were tilted distally while the root of the lower left second incisor was tilted mesially .
the patient had a follow up cbct scan at 18 months interval which showed two residual isolated areas of radiolucency in the mandible of approximately 1.0  cm in diameter : one in the lower central incisors area , the other in the lower left second premolar area .
histology of the specimens confirmed a recurrent giant cell lesion in the lower left premolar region .
however , histology of the second lesion in the lower right incisor region was reported as a granular cell tumour ( fig .
3 ) . histopathology demonstrated cells that were polygonal shaped with oesinophilic cytoplasm , strongly positive on pas staining .
the cells had a syncytial arrangement . where present , the stroma was densely fibrous . only occasional inflammatory cells were noted .
follow up , the patient had developed some granulation type tissue in the lower labial mucosa opposite the anterior surgery site .
this new mucosal lesion was excised under local anaesthetic and demonstrated a recurrent granular cell tumour on histopathology ( fig .
a further cbct scan was carried out demonstrating no bony infill of the lesion of the anterior mandible and a possible increase in size .
the lesion in the lower left premolar region had shrunk in size and there was good bony infilling .
further curettage of the lesion in the anterior mandible with removal of the overlying soft tissues and periosteum was carried out .
histology demonstrated features of fibrosis only in the bony cavity , and features of granular cell tumour in the soft tissues specimen(fig .
granular cell tumours ( gct ) are rare in the mouth , , , , , , .
the first gct described was the congenital granular cell epulis ( cgce ) of the newborn in 1871 .
it was not until 1962 when couch and associates   described two cases of central gct .
there is a slight variation in age group incidence when the gct occurs in the jaw or in the soft tissues . in a series of 18 gct of adults and 7 cases of cgce , dan et al
.   found that 72.2% of adults involved were females , with an average age in the fourth decade and mainly affecting the tongue , followed by the skin and subcutaneous tissues of the head and neck region .
carol et al .   found a 2:1 female : male incidence ratio in adult gct with the tongue affected in two thirds of cases , followed by the buccal mucosa , lips and soft palate .
central gct occur most commonly in the fifth decade and in females predominantly in the posterior part of the mandible , , , , .
it has been suggested that there is a 12% rate of malignant transformation in all gct .
almost all of the reports of malignant variants in the literature concern tumours outside the mouth .
gct in the soft tissues present usually as a solitary , firm , painless lumps .
local excision is the treatment of choice although there have been reports of recurrence . in our case ,
central gct most commonly present as a swelling and expansion of the affected area , , .
the lesion has a well defined radiolucency with or without sclerotic borders , , , , .
curettage and surgical excision has been described as an effective treatment option with no reported recurrence , , , , . however , one case in the literature showed recurrence 13 years after it was initially curetted with no extraction of the related teeth .
curettage of the bony cavity was successful as the final bony biopsy result showed fibrosis only with no recurrence .
however the residual soft tissue gct opposite the bony lesion recurred and needed a second procedure . under the light microscope , gct share a common morphological picture , they are composed of round to polyhedral cells with small round or oval nuclei . the cells cytoplasms contain oesinophlic lysosomes .
on the other hand , immunostaining shows variations between cgce , adult gct and central gct , , , , .
cgce and central gct share negative reaction to s-100 marker , , , , . however , there are reports of a positive reaction of the central gct to the cd68 marker   which has been supported in our case .
this has lead to the neurogenic theory for the origin of this type of lesion in contrast to the old myogenic theory first advocated by abrikossof   which is based on light microscopy observations . to add to the uncertainty of histogenesis
, some authors believe that demonstration of these marker proteins by immuonstaining is a measure of gene expression and cytodifferntiation rather than an indicator of cellular origin .
the gct in our case has developed in a site of a previous giant cell lesion .
this raises a question whether this was a mere coincidence or if the giant cell lesion was a precursor .
a. mosea jordanian board ( omfs ) , ffdrcsi ( osom ) , dip imp dent rcs(eng ) , mfdrcsi , bds .
highlightsgranular cell tumours are rare in the mouth.a unique case of granular cell tumour in the site of a previous giant cell lesion of the anterior mandible is presented here.curettage of the lesion along with conservative excision of the overlying soft tissue extension is an acceptable treatment option .