Oral granular cell myoblastoma: an immunohistochemical study

Unusual presentation of granular cell tumour of buccal mucosa

Granular cell tumour (GCT) is a rare soft tissue lesion which many consider to have malignant potential of yet unknown aetiopathogenesis. Oral GCT lesions may occur in an area of leucoplakia and are predominantly present on the tongue. This case study highlights an uncommon presentation of this condition located on the buccal mucosa and illustrates the need for meticulous evaluation of suspicious lesions. Due to the malignant risk associated with GCT lesions, it is important to make the correct diagnosis and ensure complete surgical excision for these cases. Ongoing long-term follow-up is also indicated to monitor for recurrence or malignancy.

Oral granular cell tumour: A multicentric study of 56 cases and a systematic review

OBJECTIVE

Granular cell tumour (GCT) is a benign neoplasm that originates from Schwann cells. Within the oral cavity, it usually appears as a lingual nodule and especially amongst female adults. Histologically, GCT shows a proliferation of polygonal cells with eosinophilic granular cytoplasm, which can be associated with a pseudoepitheliomatous hyperplasia (PEH). In this study, we analyse the main clinicopathological data of intraoral GCT and we compare our results with previous studies.

MATERIAL AND METHODS

We have studied a series of 56 cases of oral GCT in Spain and Brazil, and we have conducted a systematic review in PubMed, Web of Knowledge and Scopus databases, using the keywords: "granular cell tumour" and oral.

RESULTS

In our series, GCT appeared as an asymptomatic benign tumour that is more frequent in women and in the tongue. PEH was observed in 32% of the lesions. In the review, we collected 282 cases of oral GCT with a similar clinical profile; seven patients had multiple lesions, and 33% of the cases presented PEH. No cases of malignant oral GCT have been described to date. GCT is an uncommon oral benign neoplasm, mainly unique and asymptomatic, derived from Schwann cells.

CONCLUSIONS

Although the etiopathogenesis of this oral tumour is unknown, its characteristics suggest that it could have a reactive nature. Conducting a complete clinicopathological study in all intraoral GCT is fundamental in order to dismiss other entities, including oral carcinoma.

Characterization of uterine granular cell tumors in B6C3F1 mice: a histomorphologic, immunohistochemical, and ultrastructural study

The granular cell tumor is most often a benign neoplasm of uncertain origin. Four uterine granular cell tumors in control and treated female B6C3F1 mice were identified in chronic studies at the National Toxicology Program. Two tumors occurred in untreated control animals and 2 in treated animals receiving different compounds. Tissue sections were evaluated histologically and stained with hematoxylin and eosin, periodic acid-Schiff with diastase resistance, Masson's trichrome, toluidine blue, phosphotungstic acid-hematoxylin, and stained immunohistochemically with a panel of antibodies to muscle (desmin, alpha smooth muscle actin), neural (S-100, neuron specific enolase), epithelial (wide-spectrum cytokeratin), and macrophage (F4/80) markers. The main histomorphologic feature of tumor cells was the presence of abundant cytoplasmic eosinophilic granules that stained positive for periodic acid-Schiff with diastase resistance. Tumors varied in appearance and were comprised of sheets and nests of round to polygonal cells with distinct borders. Nuclei were hyperchromatic, pleomorphic, and centrally to eccentrically located and often contained single nucleoli. Occasional multinucleated giant cells were observed. Tumors were pale pink and homogeneous with trichrome stain and negative with toluidine blue. Three tumors had positive to weakly positive immunoreactivity for desmin, and 1 was positive for alpha smooth muscle actin. Expression of S-100, wide-spectrum cytokeratin, and neuron-specific enolase was negative for all tumors. Ultrastructurally, prominent electron-dense cytoplasmic granules were abundant and contained secondary lysosomes with heterogeneous lysosomal contents. The characteristics of these uterine granular cell tumors were suggestive of a myogenic origin.

Granular cell tumour of the breast

Eight cases of benign granular cell tumour of the breast are reported. Seven patients were women and one was male. The age at the time of the excision ranged from 17 to 73 (average 40.1) years. All tumours were positive for S-100 protein and negative for keratin, myoglobin and gross cystic disease fluid protein. In two cases ultrastructural studies revealed findings identical to those in the previously reported cases of granular cell tumours. None of these cases were diagnosed preoperatively. In six cases the clinical and mammographic findings, and in one case the frozen section, led to an erroneous diagnosis of malignancy. The clinico-pathological features of the cases are delineated in order to draw attention to a benign condition which closely simulates malignancy.

A desmoplastic granular cell tumour of the oral cavity: report of a case

A case of granular cell tumour of the buccal mucosa demonstrating marked desmoplasia is presented. The bulk of the tumour is composed of dense collagenous stroma, which surrounds isolated nests of tumour cells. Since the histomorphologic appearance of this variant is different from that usually seen in this lesion, the diagnosis is supported by immunohistochemical demonstration of S-100 and Vimentin in the tumour cells. The authors believe that this case represents the first report of a desmoplastic granular cell tumour of the oral tissues.

Granular cell tumor of a digital nerve

Granular cell tumor is an infrequently encountered albeit not rare neoplasm considered to be of neuroectodermal origin. An example of a benign granular cell tumor originating within a digital nerve is presented. The authors employed routine light microscopic techniques and immunostaining which demonstrate features of the granular cells reflecting structural and functional characteristics of Schwann's cells and support neuroectodermal derivation. Granular cell tumor is ubiquitous in location but occurs more frequently in tongue, skin and subcutaneous tissue. Clinical features are not specific, and a histologic evaluation is required for diagnosis. Circumscription and lack of cellular pleomorphism define a benign process. However, irrespective of its histologic appearance, the biologic potential is uncertain. Complete excision suffices as treatment for benign tumors.

Immunoreactivity of granular cell lesions of skin, mucosa, and jaw

Granular cell lesions from many different sites share similar light and electron microscopic features. Immunologically, however, these lesions do not appear to be a homogenous group. This study determines the extent of immunologic heterogeneity of granular cell lesions from a wide variety of sites in skin, mucosa, and jaw. Thirty-one granular cell lesions (26 granular cell tumors [GCT] and five other granular cell lesions) from 18 different sites were evaluated immunohistochemically for keratins, vimentin, desmin, muscle actin, ACT, HLA-DR, and S-100 protein. Paraffin-embedded sections were utilized with an avidin-biotin complex immunoperoxidase technique. Except for ameloblastomas, all lesions were negative for keratin and positive for vimentin. All lesions were negative for desmin and actin. Positive ACT reactivity was found in one of seven GCT of tongue, a colonic lesion, a nose lesion, and a granular cell ameloblastic fibroma. All lesions were positive for HLA-DR except a few in which fixation appeared inadequate. S-100 immunoreactivity was found in all lesions except the congenital epulis, a GCT of the skin of the nose, a colonic lesion, and the odontogenic tumors. The antigenic profile of GCT of skin and mucosa is consistent with Schwann cell origin. However, some GCT and other granular cell lesions appear to be derived from macrophages, epithelial cells, or other cells. The expression of HLA-DR by granular cells is believed to be unrelated to cellular origin but rather to some common immunologic function.

Granular cells in odontogenic and non-odontogenic tumours

Granular cells can occur in various odontogenic and non-odontogenic tumours. 5 granular cell lesions, one granular cell ameloblastoma, one so-called granular cell ameloblastic fibroma and three granular cell tumours were examined immunohistochemically for the intermediate filaments cytokeratin, vimentin, desmin, neurofilaments and the neural markers NSE and S-100 protein. The granular cell tumors (granular cell myoblastoma) showed positive staining for vimentin and S-100 protein. Only vimentin could be demonstrated in the granular cells of the so-called granular cell ameloblastic fibroma, whereas the granular cell ameloblastoma showed positive staining only for cytokeratin. A positive reaction with S-100 protein was not found in any of the odontogenic tumours. In our opinion the mesenchymal odontogenic granular cell is a fibroblast, whereas the epithelial granular cell is derived from enamel epithelium. The term "granular cell ameloblastic fibroma" is a misnomer, as a number of these tumours are probably central odontogenic fibromas exhibiting granular cell transformation.

Oral granular cell tumors: a clinicopathologic and immunocytochemical study

To investigate the histogenesis of the granular cell, a large series of granular cell tumors was studied for clinical and histopathologic features with emphasis on immunocytochemical markers. The nongingival granular cell tumors (NGGCT) were found to be more prevalent among females than males by a ratio of 2:1 and arose on the tongue (67%), the buccal mucosa (13%), the lips (8%), the soft palate (6%), and other sites (6%). With the use of the avidin-biotin-peroxidase method, polyclonal rabbit antisera were employed. The antisera were directed to the following antigens: S-100 protein, myoglobin, myosin, actin, desmin, alpha-1-antitrypsin, and muramidase. Results indicated that granular cell tumors are not homogenous for immunocytochemical markers. Nongingival granular cell tumors were universally positive for S-100 protein and failed to exhibit immunoreactivity for myogenous or histiocytic markers. Alternatively, the gingival granular cell tumor of infancy was negative for all markers, whereas rhabdomyoma was reactive with myogenous markers and a subpopulation of tumor cells displayed S-100 protein immunoreactivity. The granular cell ameloblastoma was reactive only with antiserum to alpha-1-antitrypsin. Ultrastructurally, granular cells from one of two NGGCT showed a direct evolution from skeletal muscle fibers. It is concluded that the oral NGGCT is a tumor positive for S-100 protein that may arise from muscle or nerve sheath.

Multiple granular cell tumors of the palate

A report of a case of bilateral granular cell tumors of the soft palate is presented. This is an unusual location for the tumor and is the first report of bilateral tumors at this site.

Granular cell myoma and schwannoma: fine structural and immunohistochemical study

We present the histological, ultrastructural, and immunohistochemical findings of two granular cell tumors of different histogenesis: a mediastinal granular cell schwannoma, and an uterine granular cell leiomyoma. Ultrastructurally the mediastinal tumor showed granular cell changes of the Schwann cells which were reactive for S-100 protein and Leu 7 antigen, but not for actin, desmin, CEA, EMA, or cytokeratin. Ultrastructural study of the uterine lesion demonstrated smooth muscle cells with only a few "autophagic" facuoles to cells nearly replaced by lysosomes. Immunohistochemically this tumor showed reactivity for actin, desmin, and Leu 7 antigen, but was S-100 protein, CEA, EMA, and cytokeratin negative.

Granular-cell tumours of the skin do not express carcino-embryonic antigen

Granular-cell tumour (GCT) of the skin is an uncommon tumour of disputed histogenesis, that has been subjected to several immunohistochemical studies. The controversy existing in the literature concerning the expression of carcinoembryonic antigen (CEA) by GCT prompted us to study a series of 17 cases of cutaneous GCT by using an avidin-biotin-immunoperoxidase technique on routinely-processed tissue sections. No CEA activity was detected in any of the tumours screened. The reasons for this controversy are discussed.

Relationship between fibronectin and lymphoid cells in buccal mucosa, labial salivary glands and palatine tonsil

The distribution of fibronectin in human buccal mucosa and labial salivary glands and its relationship to lymphoid cells was studied using an immunoperoxidase technique and monoclonal and polyclonal antibodies. In all specimens fibronectin was associated with basement membranes of epithelia, vascular endothelium and perineural sheaths. In histologically normal areas of buccal mucosa fibronectin was distributed as a sparse network in the superficial lamina propria. A more extensive network of fibronectin was found within the lamina propria of mucosal specimens infiltrated with T lymphocytes, whereas fibronectin was absent in areas occupied by B lymphocytes. A similar relationship between lymphocyte type and the presence of a fibronectin network was found in labial glands and palatine tonsil. Fibronectin was not detected within oral, salivary gland, tonsillar crypt or capsular epithelium.

Immunohistochemical study of granular cell tumours. Demonstration of neurone specific enolase, S 100 protein, laminin and alpha-1-antichymotrypsin

Nine granular cell tumours were investigated with poly- or monoclonal antisera to neurone specific enolase (NSE), glial enolase (GE), S 100 protein, alpha-1-antichymotrypsin, lysozyme, laminin, neurofilament (NF), glial fibrillary acidic protein (GFAP), brain creatine kinase (CK), different cytokeratins (Keratin Dako, PKK1), tissue polypeptide antigen (TPA), carcinoembryonic antigen (CEA), desmin, myoglobin and leukocyte common antigen (LCA), using immunoperoxidase-methods on formalin fixed paraffin embedded sections. While five tumours from adults show specific cytoplasmic staining for NSE and S 100, three congenital tumours, two from the gingiva and one from palatine, show only a weak reaction for NSE, reflecting a possible origin from mature and immature Schwann cells, respectively. However, one subcutaneous tumour from near the clavicule of a ten year old girl differs from the other eight tumours by its specific cytoplasmic staining for alpha-1-antichymotrypsin only, supporting the view that there are granular cell tumours of histiocytic origin. In addition, the five adult NSE-S100 tumours show strong laminin-immunostaining around the single small or syncytial granular cells, whereas pericellular laminin is not detectable in the histiocytic nor in the three congenital tumours. None of the tumours shows any staining for lysozyme, epithelial, muscular, leukocyte, neurofilament or glial antigens.

Macrophages in oral lichen planus

The presence and distribution of macrophages within 15 non-ulcerated lesions of oral lichen planus was investigated using an immunoperoxidase technique for the detection of the macrophage markers lysozyme and alpha 1 antitrypsin. All specimens contained mononuclear lysozyme and alpha 1 antitrypsin positive cells which were concentrated in a band immediately beneath the epithelium and often associated with areas of damaged basal cells. Cell counts revealed that 11% of the positive cells were in the epithelium and 89% in the lamina propria. Approximately 61% of all positive cells were found within a 125 micron wide zone centred on the basement membrane. These results suggest that in oral lichen planus macrophages are in close proximity to the epithelial basal cells, where cell damage occurs, and play a role in the pathogenesis of this condition.

Intra-epithelial hyaline bodies in odontogenic cysts: an immunoperoxidase study

Fourteen dental cysts containing intra-epithelial hyaline bodies were stained for keratin, Factor VIII-related antigen, haemoglobin and fibrinogen using immunoperoxidase methods. Although the hyaline bodies were negative for all tested antigens fibrinogen was detected in the cores of some circular and polycyclic forms. These observations do not provide support for the proposed keratin, capillary endothelium or erythrocyte nature of these structures. The core staining for fibrinogen may support the theory that hyaline bodies are produced by a cellular reaction to extravasated serum.

Histogenesis of granular cell tumour--an immunohistochemical and ultrastructural study

Fifteen cases of granular cell tumour of superficial soft tissues or tongue were immunohistochemically evaluated for different types of intermediate filament proteins and for laminin, a glycoprotein of basal laminae. Four of the tumours were studied ultrastructurally. The tumour cells appeared to contain only vimentin-type of intermediate filament protein. The lobules of tumour cells were surrounded by laminin-positive material, but in contrast to schwannomas and neurofibromas, the individual tumour cells were not covered by laminin. In line with the immunohistochemical observations, by electron microscopy basal lamina-like material could not be demonstrated between individual cells, but only surrounding groups of cells. Lysozyme, a histiocytic marker, was absent in the tumour cells. Our results do not confirm any particular cell type for the histogenetic origin of granular cell tumour, but suggest that it may rather be derived from uncommitted possibly nerve-related mesenchymal cells.

Oral granular cell lesions. An immunohistochemical study with emphasis on intermediate-sized filaments proteins

Six cases of oral granular cell lesions were studied with respect to intermediate-sized filaments (IF), peanut lectin binding (PNL) and muramidase activity by means of the peroxidase antiperoxidase technique. The tumours included three granular cell myoblastomas of the tongue (GCM) two cases of congenital gingival granular cell tumour (CGGT) and one granular cell ameloblastoma (GCA). Every tumour studied showed intracytoplasmic PNL binding whereas muramidase was negative in all cases. Vimentin expression was demonstrated in the CGGT and to a lesser extent in the GCM, but was absent in the GCA which was positive for keratin. Desmin and glial fibrillary acidic protein (GFAP) were not present in any of the lesions. These data demonstrate that PNL binding might be considered to be a common feature of granular cells regardless of their histogenesis. Lysosomes are supposed to represent the intracellular binding sites for this marker. Moreover it is shown that histomorphological identity between the granular cells of CGGT and GCA does not signify identity in histogenesis since the former are of mesenchymal derivation while the latter, from their intermediate filament protein types appear to originate from epithelium.

Ultrastructure of the congenital epulis

This report presents the ultrastructural features of a congenital epulis. The granular cells of the epulis were packed with numerous membrane bound cytoplasmic granules containing particles, small vesicles, and electron-dense materials. These granules were negative in immunohistochemical reaction for CEA (DAKO PAP KIT). Cytoplasmic organelles such as mitochondria, rough surfaced endoplasmic reticulum, and Golgi apparatus, were absent. Nuclei were markedly indented. Occasionally, banded intracellular collagen fibrils were observed within the cytoplasm. Some of these fibrils were surrounded by a limiting membrane, whereas others appeared to lie free in the cytoplasm. The collagen fibrils were also seen within a deep invagination of the cell surface. There was no basal lamina around the granular cells. Sporadically, mast cells with many granules containing lamellar formations were found between the granular cells. These observations support the idea that granular cells of the congenital epulis are derived from mesenchymal cells, probably fibroblasts.

Granular cell myoblastoma: an immunoperoxidase study using a variety of antisera to human carcinoembryonic antigen

Immunoperoxidase staining using five antisera to human carcinoembryonic antigen (CEA), including a mouse monoclonal antibody, was performed to investigate the expression of CEA reactivity in ten cases of granular cell myoblastoma. The granular cells were negative with four of the antisera although control sections of CEA producing colon carcinoma were positive. The single positive antiserum gave intense granular cytoplasmic staining of all tumour cells in the ten specimens studied. This reactivity was abolished after absorption of the antiserum with a perchloric acid extract of human lung to remove cross-reacting antibodies against non-specific cross-reacting antigen (NCA); a procedure which did not affect the staining of colon carcinoma specimens. The results indicate that the granular cells do not contain CEA but express a related antigen and that care in the choice of primary antiserum is important if the immunocytochemical detection of this antigen is to be used as a diagnostic aid.