Granular cell tumours (GrCTs) are uncommon soft tissue tumours that are usually benign (approximately 0.5%-2.0% have been reported as malignant). They are very rarely found at the extremities. Differentiating a malignant GrCT from a benign one is important as the former is aggressive and has a poor prognosis, whereas the latter, after surgical resection, has excellent outcomes. A malignant lesion can be suspected on clinical presentation and confirmed via histopathological examination using the Fanburg-Smith criteria.
Granular cell ameloblastoma (GCA) is a well recognized variant of follicular ameloblastoma with extensive granular cell change. In contrast, plexiform granular cell odontogenic tumor (PGCOT) is a rare and recently described lesion characterized histologically by a monophasic plexiform pattern of granular cells. In this paper, two cases of an unusual granular cell odontogenic tumor exhibiting combined features of these two entities are described along with their immunohistochemical characteristics. The granular cells of both the GCA and PGCOT areas showed similar patterns of expression for keratin and S-100, which differed from those of typical ameloblastoma. No reactivity for desmin or vimentin was noted. The histomorphologic and immunohistochemical features of these hybrid tumors suggest that the granular cells present have a common origin, most probably the odontogenic epithelium.
Oral granular cell tumour is a fairly rare lesion with a predilection for the tongue. Seven cases (6 females, 1 male) of oral granular cell tumour were seen during the 40 year period (1967-2006) in Stomatology Unit, Institute for Medical Research (IMR) in which 5 cases were located at the tongue. All the cases presented as a single swelling and excisional biopsies were carried out in all cases.
Tumours that occur in the oral cavity may contain granular cells as a component of their pathology. A more common granular cell lesion occurring in the head and neck region is the granular cell tumour (GCT) that usually arises in the tongue or the buccal mucosa. Granular cell tumours are very rare in the parotid gland with only 11 cases previously reported in the English literature. We report a case of a benign tumour involving the parotid gland of a young female patient. The case was diagnostically challenging due to the large proportion of granular cells masking the underlying pathology. Histopathological features and immunohistochemical analysis favoured a diagnosis of a benign GCT. The present report provides an insight into the differential diagnosis and attempts to characterise the granular cells with the use of the wellestablished immunohistochemical markers and conventional histopathological techniques.