Granular-cell ameloblastoma

Large mandibular mass with several floating teeth: granular cell ameloblastoma

Ameloblastomas are benign, locally aggressive, odontogenic epithelial neoplasms. We present a patient with a rare granular cell ameloblastoma. This is a case report and literature review conducted from July 2022 to the present. Our 52-year-old male patient presented to the clinic with a several month history of right lower lateral lip swelling and dental complaints. On imaging and physical exam, we noticed a large heterogenous, multiloculated, expansile lesion of the right mandible with several floating teeth. After incisional biopsy confirmed multicystic granular cell ameloblastoma, the patient underwent successful surgical resection and osteocutaneous fibula free-flap reconstruction. At the time of writing this report, 7 years after resection, the patient is alive with no evidence of recurrence. The recognition and treatment of mandibular lesions can represent significant clinical challenges, especially for rarely seen subtypes such as the granular cell ameloblastoma. Special consideration must be given for the identification and treatment of these neoplasms.

Analysis of the 100 most cited articles on ameloblastoma

OBJECTIVES

An increasing number of articles are published each year. The aim of this is to provide a list of the 100 most cited articles on the subject of ameloblastoma.

METHODS

A bibliographic search was performed on Google Scholar (GS), Microsoft Academic (MA), and Dimensions for ameloblastoma. A ranking was created in order of citation density. Graphical representations of keywords and authorship were created with VOSviewer. Statistical analysis was performed and only results with a 95% confidence interval were considered significant.

RESULTS

A helpful list of top 100 articles was developed to help professionals in a variety of ways. Some curiosities are discussed about this scientometric analysis in ameloblastoma articles.

CONCLUSIONS

A useful list of the top 100 most cited articles on ameloblastoma has been provided. Bibliometric and altmetric analysis using Google Scholar, Microsoft Academic, and Dimensions is a free and excellent tool, not only as a citation manager but also as a study reference.

Ameloblastoma with distinctive granular cell pattern: an 8 case study

Ameloblastoma with granular cell pattern (AGC) is classified as an unusual histological subtype of solid/multicystic ameloblastoma, characterized by granular changes in stellate-like cells located within the inner portion of the epithelial follicles. Studies have revealed that lysosomal overload causes cytoplasmic granularity; however, the mechanism involved remains poorly understood. Here we report on eight cases of granular cell ameloblastoma, in the posterior region of the mandible. The age of the patients included in this case series ranged from 35 -64 years old and 87.5% of cases occurred in non-Caucasians, with a slight gender predilection for men (62.5%). There was no evidence of recurrence, and the majority of the cases were treated with surgical resection (87.5%). All tumors displayed histopathological features consistent with the diagnosis of ameloblastoma with granular cell pattern.

Granular Cell Basal Cell Carcinoma of the Skin. Report of a Case with Immunocytochemical Positivity for Lysozyme

Granular cell tumors have been described in many sites throughout the body. To our knowledge, few cases have been described in the literature. We report here the sixth case, in which positivity for lysozyme was also observed for the first time. The problems of the histogenesis and differential diagnosis of this rare variant of basal cell carcinoma are also discussed.

Aggressive granular cell ameloblastoma: Report of a rare case

Granular cell ameloblastoma is a slow growing odontogenic ectodermal tumor. The tumor shows typical ameloblastoma with the cells showing eosinophilic granularity. This variant of ameloblastoma is aggressive with high recurrence rates. We report a case of aggressive ameloblastoma of granular cell variant.

Recurrent ameloblastoma of the mandible with unusual granular cell component

Ameloblastomas can present in various clinical and histomorphologic patterns. The granular cell variant accounts for only 3.5% to 5% of ameloblastomas. The aim of this case report is to present an example of ameloblastoma with unusual granular cell component, affecting a 63-year-old woman, in which both the inner and peripheral layers of follicles composed exclusively by eosinophilic granular cells. Assessment of the immunohistochemical and histochemical profile of the lesion was performed and the challenges of such a diagnosis were also addressed.

Granular cell ameloblastoma: case report of a particular ameloblastoma histologically resembling oncocytoma

Granular cell ameloblastoma is classified as a histological subtype of solid/multicystic ameloblastoma. Usual granular cell ameloblastoma is histologically characterized by granular changes of stellate-like cells located in the inner portion of the epithelial follicles. Here we report a case of another type of granular cell ameloblastoma, showing predominant anastomosing double-stranded trabeculae of granular cells. This type of granular cell ameloblastoma is extremely rare, and the World Health Organization classification does not contain the entity. We tentatively termed it 'anastomosing granular cell ameloblastoma' in this report. The present case suggests the importance of differential diagnosis because the histology of 'anastomosing granular cell ameloblastoma' resembles that of salivary gland oncocytoma rather than that of usual granular cell ameloblastoma. The trabeculae observed in our case continued to the peripheral cells of a small amount of epithelial sheets of plexiform ameloblastoma, and the tumor cells were positive for CK19, which is regarded as an immunohistochemical marker of odontogenic epithelium. Similar to usual granular cell ameloblastoma, the tumor cells had CD68-positive granules. For precise diagnosis of this condition, immunohistochemistry using CK19 and CD68, as well as detailed histological observation, are recommended.

Massive granular cell ameloblastoma with dural extension and atypical morphology

Ameloblastomas are rare histologically benign, locally aggressive tumors arising from the oral ectoderm that occasionally reach a gigantic size. Giant ameloblastomas are a rarity these days with the advent of panoramic radiography in routine dental practice. Furthermore, the granular cell variant is an uncommon histological subtype of ameloblastoma where the central stellate reticulum like cells in tumor follicles is replaced by granular cells. Although granular cell ameloblastoma (GCA) is considered to be a destructive tumor with a high recurrence rate, the significance of granular cells in predicting its biologic behavior is debatable. However, we present a rare case of giant GCA of remarkable histomorphology showing extensive craniofacial involvement and dural extension that rendered a good prognosis following treatment.

Ameloblastic carcinoma: A clinicopathologic dilemma - Report of two cases with total review of literature from 1984 to 2012

Ameloblastic carcinoma (AC) is a rare primary odontogenic tumor that has histological features of both ameloblastoma and carcinoma. A total number of 92 case reports speak about its rare incidence, affecting mostly the mandible as a locally destructive lesion. The maxilla is affected even more rarely as only 35 cases have been reported until 2012 in scientific literature. The clinical course of AC is generally aggressive, with extensive local bone destruction. The most common clinical features include swelling, pain, trismus, significant bone resorption with tooth mobility, dysphonia and intraoral fistula. We report two cases of AC with aggressive behavior.

Pathogenesis and nomenclature of odontogenic carcinomas: revisited

Odontogenic carcinoma is rare group of malignant epithelial odontogenic neoplasms with characteristic clinical behavior and histological features, which requires an aggressive surgical approach. The pathogenesis of this rare group remains still controversial and there have been many varied opinions over the classification of this rare group of lesions. As there have not been many reviews on odontogenic carcinoma, the existing knowledge is mostly derived from the published case reports. This review is discussing the pathogenetic mechanisms and is updating the knowledge on nomenclature system of less explored odontogenic carcinomas. This review might throw light on the pathogenesis and nomenclature system of odontogenic carcinoma and this knowledge may be applied therapeutically.

Rare giant granular cell ameloblastoma: a case report and an immunohistochemical study

Aims. The aim is to present a case of rare giant granular cell ameloblastoma and to review the pertinent literature highlighting the molecular aspects of its pathogenesis by analyzing the expression of CD-68, Bcl-2, and β -catenin. Methods. H and E stained sections showed large odontogenic islands showing peripheral ameloblast-like cells and central stellate reticulum-like cells with extensive granular cell transformation surrounded by fibrous stroma. Polyclonal rabbit anti-CD 68, anti-Bcl2, and anti- β -catenin were stained immunohistochemically. Results. CD-68 showed a moderate to strong staining intensity in granular cells. Moderate staining of Bcl-2 was expressed by the peripheral columnar cells of tumor islands and negative in the granular cells. Expression of β -catenin was generally weak, except for only the focal areas that showed a moderate staining intensity and weak in peripheral cells. Conclusion. The present case of giant granular cell ameloblastoma is a rare entity. Development of monstrous size is indicative of ameloblastomas persistent growth. Granular cell transformation in ameloblastomas probably occurs as a consequence of extensive molecular changes. Immunohistochemical studies help us to know the pathogenesis of this granular cell ameloblastoma. Therefore, an effort has been made here to study the expression of Bcl-2, CD-68, and β -catenin.

Investigation of basement membrane proteins in a case of granular cell ameloblastoma

Granular cell ameloblastoma is a rare, benign neoplasm of the odontogenic epithelium. A case of massive granular cell ameloblastoma in a 44-year-old Thai female is reported. Histopathological features displayed a follicular type of ameloblastoma with an accumulation of granular cells residing within the tumor follicles. After treatment by partial mandibulectomy, the patient showed a good prognosis without recurrence in a 2-year follow-up. To characterize the granular cells in ameloblastoma, we examined the expression of basement membrane (BM) proteins, including collagen type IV, laminins 1 and 5 and fibronectin using immunohistochemistry. Except for the granular cells, the tumor cells demonstrated a similar expression of BM proteins compared to follicular and plexiform ameloblastomas in our previous study, whereas the granular cells showed strong positivity to laminins 1 and 5 and fibronectin. The increased fibronectin expression in granular cells suggests a possibility of age-related transformation of granular cells in ameloblastoma.

Malignant ameloblastoma: concurrent presentation of primary and distant disease and review of the literature

Malignant ameloblastoma is a rare tumor of odontogenic origin with a metastatic focus. Distant metastatic disease is found most commonly in the lungs. A review of the literature shows that most cases of malignant ameloblastoma involve a disease-free period from primary tumor extirpation to the discovery of metastasis. This report describes the case of a 56-year-old man presenting with ameloblastoma of the maxilla and a solitary pulmonary metastasis concurrently. This represents a rare case in which there is a simultaneous diagnosis of primary ameloblastoma and a metastatic lesion. Appropriate workup for ameloblastoma includes surveillance for metastatic disease. Surgical resection of primary and distant disease is recommended. Chemotherapy and radiation may play a role in palliation when resection of metastatic disease is not feasible.

Granular cell basal cell carcinoma

A 69-year-old woman presented with a 2-year history of a slowly growing tumour on the nose. The clinical diagnosis was basal cell carcinoma (BCC) and a complete excision was performed. Histologically, the tumour had the general features of a BCC but with sheets and nests of cells with granular cytoplasmic changes in the centre of the lesion. A pathological diagnosis of granular cell BCC was made. On immunohistochemical examination, the tumour cells were Ber-EP4, cytokeratin AE1/AE3 and cytokeratin CAM 5.2 positive but S100 protein negative. Only the granular cells were CD68 antigen (monoclonal antibody KP1) positive.

Ameloblastic carcinoma: An analysis of 14 cases

OBJECTIVES

To present the classifications of malignant ameloblastomas, provide histopathologic guidelines for the diagnosis of ameloblastic carcinoma, and discuss treatment and long-term follow-up.

STUDY DESIGN

Fourteen archival specimens of ameloblastic carcinoma with detailed treatment and follow-up documentation were identified by the authors.

RESULTS

Traditional methods of microscopic observation form the basis for diagnosis. Histopathologic features of ameloblastic carcinoma include lack of differentiation, hypercellularity, high mitotic index, vascular invasion, and neural invasion.

CONCLUSION

The long-term follow-up findings in this study support the concept that aggressive surgical intervention provides the best chance for survival. Patients treated otherwise had recurrence. The patients with the highest number of recurrences did not survive the disease.

Follicular/desmoplastic hybrid ameloblastoma with radiographic features of concomitant fibro-osseous and solitary cystic lesions

We report a case of ameloblastoma radiographically suggestive of a complication of fibro-osseous and solitary cystic lesions. A 35-year-old woman was referred to our hospital for treatment, complaining of swelling in the left premolar region of the mandible. Radiological findings indicated a mixed radiopaque and radiolucent lesion in the region of the left mandibular canine and first premolar as well as a solitary cystic lesion in the mandibular second premolar region. Following biopsy, resection of mandible was performed under general anesthesia. Histopathologic examination identified follicular-type ameloblastoma with partial desmoplastic findings. Conventional radiography and computed tomography were not useful in indicating the relationship between the mixed and solitary cystic lesions. However, magnetic resonance imaging was instrumental in elucidating this relationship.

Ameloblastoma: a clinical, radiographic, and histopathologic analysis of 71 cases

OBJECTIVES

The purpose of this study was to compare the clinical, radiologic, and histopathologic features of 71 intraosseous ameloblastomas.

STUDY DESIGN

Data with respect to the patients' ages, sex, tumor locations, and surgical treatment history, as well as the radiographic findings and number of recurrences, were analyzed. The histologic types of and radiologic findings regarding tumors with higher recurrence rates were also investigated.

RESULTS

The patients' ages at biopsy ranged from 11 to 70 years (mean, 30.4 years). Thirty-nine (54.9%) of the 71 subjects were males, and 32 (45.1%) were females. Sixty-two (87.3%) of the 71 ameloblastomas were located in the mandible. Swelling was the most common symptom and was experienced by 27 (38.0%) patients. Radiographically, 42 (59.2%) of the 71 tumors were unilocular with a well-demarcated border. Of the remaining 29 cases, 14 were multilocular, 2 were of soap-bubble shape, and 13 were unknown in appearance. The most common histologic pattern was plexiform, rather than follicular or acanthomatous. Sixteen cases of ameloblastoma had developed in a cyst. The overall recurrence rate was 21.1%, and the average age of the patient at recurrence was 26.4 years.

CONCLUSIONS

When the diagnosis of ameloblastoma in young people remains in doubt after clinical and radiologic examination, a biopsy is necessary. Long-term follow-up at regular intervals after surgery is also recommended.

Granular Cell Variant of Atypical Fibroxanthoma

We report a case of atypical fibroxanthoma of the ear in which the dominant part of the tumor has granular cell appearance. Areas identical to conventional atypical fibroxanthoma were present only at the lateral infiltrating borders. Histologically the granular cells resembled those of the classical granular cell tumors but exhibited significant pleomorphism and a high mitotic rate. Immunostains for vimentin, CD68 and NK1/C3 were positive but for S-100, HMB-45, myogenic and epithelial markers were negative. The predominance of the granular cells in an atypical fibroxanthoma supports the concept that a small subset of tumors with granular cell phenotype are of nonneural origin.

Congenital CD34-positive granular cell dendrocytosis

Granular cell tumors involving the skin are mostly acquired lesions. The Schwann cell origin of these lesions is supported by positive immunostaining for S-100 protein and myelin basic protein. S-100- granular cell lesions rarely have been described in association with fibrous papules or dermatofibromas. The congenital variety of S-100- granular cell tumors occurs almost exclusively in the gingiva. The cell origin of these lesions is not well delineated. We report a hitherto undescribed case of a congenital cutaneous lesion which is histologically characterized by diffuse dermal infiltrates of S-100- but CD34+ granular dermal dendrocytes. The granular appearance of these CD34+ dendrocytes is attributed to an abundance of phagolysosomes. The pathogenetic mechanism of this unusual lesion remains to be elucidated.

Ameloblastic carcinoma of the jaws. A report of two cases

Two cases of ameloblastic carcinoma of the jaws are reported. Histopathologically, the lesions showed cytologic features of malignancy in addition to classical ameloblastoma patterns and were therefore documented as examples of ameloblastic carcinoma. The negative cytokeratin expression by the malignant cells on histochemical analysis is notably different from that normally observed in classical ameloblastomas.

Dermatofibroma with granular cells

A new histologic variant of dermatofibroma, only briefly alluded to in dermatological literature is reported. This tumor was located in the back of a 24-year-old man. It was present for about 2 years and had a history of trauma 2 months before excision. The lesion showed similar characteristics to those of conventional dermatofibroma as well as the presence of groups of granular cells identical to those seen in granular cell tumors. It is important to recognize dermatofibroma with granular cells because it may be confused with a variety of benign or malignant soft tissue tumors containing similar granular cells that entail different significance or prognosis. The immunohistochemical study supports a granular cell change in a dermatofibroma instead of a granular cell tumor that has been traumatized, with secondary formation of a dermatofibroma reaction.

Growth of an ameloblastoma during pregnancy: opportunity lost?

A 19-year-old pregnant woman presented with an enlarging lesion in the right mandible. She was examined by a general dental practice resident in the hospital outpatient clinic and subsequently managed by the resident as an inpatient. Both moral and ethical questions arose because of the discovery of the lesion early in the patient's pregnancy. Delay on the part of the patient while she contemplated termination of the pregnancy, compounded by loss of contact with her, eliminated the possibility of removal of the lesion during the second trimester. The patient elected to continue the pregnancy, and an en bloc procedure was used to remove the ameloblastoma.

Granular cell ameloblastoma. An immunocytochemical study

Granular cell ameloblastoma is characterized by nests of large, eosinophilic granular cells. These latter have long been the subject of debate. Two cases of granular cell ameloblastomas have been immunocytochemically stained with a panel of antibodies against human mitochondria, S-100 protein, CD 68, low molecular weight cytokeratins, chromogranin, laminin, vimentin, PCNA, bcl-2 and p-53. Granular cells exhibited a membranous positivity with cytokeratins while the non granular cells of the same tumors showed a diffuse cytoplasmic reactivity. Moreover, granular cells showed marked cytoplasmic positivity with CD68 antiserum only while human mitochondria, as well as S-100 protein antisera, were consistently negative. PCNA, bcl-2 and p-53 did not stain the granular cells. These results allow easy distinction of granular cell ameloblastomas from similar tumors exhibiting granular cell changes and indicate that the granularity in ameloblastoma cells is consequent to lysosomal overload.

Clear cell ameloblastoma or odontogenic carcinoma. A case report

An ameloblastoma of the right maxilla with a biphasic pattern of folicular ameloblastoma and clear cells, with an aggressive clinical behaviour in a 71-year-old male is reported. A literature review of clear cell ameloblastomas is made, focussing the discussion on the convenience of considering this type of ameloblastoma to be a low-grade odontogenic carcinoma.

Ameloblastoma: biological profile of 3677 cases

Available literature on ameloblastoma of the jaw was reviewed, including publications from 1960 to 1993, and compared to the latest larger review, published by Small and Waldron in 1955. The average age of patients with ameloblastoma is 36 years. In developing countries ameloblastomas occur in younger patients. Men and women are equally affected. Women are 4 years younger than men when ameloblastomas first occur, and the tumours appear to be larger in females. Dominant clinical symptoms such as painless swelling and slow growth are non-characteristic. The ratio of ameloblastoma of the mandible to maxilla is 5 to 1. Ameloblastomas of the mandible occur 12 years earlier than those of the maxilla. Ameloblastomas occur most frequently in the molar region of the mandible. In Blacks, ameloblastomas occur more frequently in the anterior region of the jaws. Radiologically, 50% of ameloblastomas appear as multilocular radiolucent lesions with sharp delineation. Histologically, one-third are plexiform, one-third follicular; other variants such as acanthomatous ameloblastoma occur in older patients. Two percent of ameloblastomas are peripheral tumours. Unicystic ameloblastomas occurring in younger patients have been found in 6%. Detailed data on 345 patients with ameloblastoma were evaluated for clarification of therapeutic approaches. Chemotherapy and radiation seem to be contraindicated. Ameloblastomas of the maxilla should be treated as radically as possible, ameloblastomas of the mandible should also be treated radically. However, ameloblastomas which radiologically appear as unilocular lesions may be treated conservatively (enucleation, curettage), whenever all areas of the cystic lumen are controllable intraoperatively. Unicystic ameloblastomas occurring in patients 15 years younger than those with multisystic ameloblastoma may be treated conservatively except in cases with invasion of epithelium into the cyst wall. Different recurrence rates have been found for histological variants of the ameloblastoma. Follicular ameloblastomas appear to recur more often than the plexiform type. Unicystic ameloblastomas reveal lower recurrence rates than "non-unicystic" ameloblastomas. The peripheral type of ameloblastoma may be excised, since conservative therapy results in low recurrence rates. Postoperative follow-up is most important in the therapy of ameloblastoma, because more than 50% of all recurrences occur within 5 years postoperatively.

Immunohistochemical study on proliferating cell nuclear antigen expression in ameloblastomas

The aim of this study is to evaluate the proliferating activity of ameloblastomas and its correlation to the biological behaviour according to each histological type. 38 cases of solid and unicystic ameloblastomas were reviewed including 1 case of ameloblastic carcinoma and 1 recurrent case. An anti-PCNA antibody, PC10(Dako), was applied for the detection of proliferating cell nuclear antigen (PCNA) in paraffin embedded tissue sections. Also 20 cases of dentigerous cysts were reviewed. In conclusion, we observed that there was no difference between the proliferating activities of the different histological types of solid ameloblastomas. Because 1 case of ameloblastic carcinoma and one recurrent case revealed remarkably high PCNA reactivity, we believe that PCNA would be useful in showing the differentiation between benign and malignant ameloblastomas. In unicystic ameloblastomas, plexiform intraluminal growth was considered to be an important feature in tumorous transformation of cystic epithelium.

Desmoplastic variant of ameloblastoma in Malaysians

Seventeen cases are reported of desmoplastic variant of ameloblastoma of the jaws observed during the years 1967-1991. There were 12 females and 5 males, and these consisted of 7 Chinese, 6 Malays, 2 Indians, 1 Sikh and 1 Kadazan. Their ages at diagnosis ranged from 21-60 years with a mean of 36.6 years. There were 10 mandibular and 7 maxillary tumours. Of these, 14 cases involved the anterior segment with extension to the premolar region in 5 cases. 60% of cases were radiologically suggestive of fibro-osseous lesions. The main mode of treatment was resection and 1 case presented with recurrence. The findings of this study were compared with those of previous reports.

'Combined ameloblastoma and odontogenic keratocyst' or 'keratinising ameloblastoma'

Four cases of either combined occurrence of ameloblastoma and odontogenic keratocyst or a rare keratinising variant of ameloblastoma are presented. The cardinal histomorphologic characteristics are simultaneous occurrence of ameloblastomatous epithelial islands with central keratinisation and multiple keratinising cysts. Immunohistochemically the tumour elements were keratin positive and occasionally S-100 protein and desmin positive. Major differential diagnosis of these neoplasms are discussed.

Granular cell basal cell carcinoma. Light microscopy, immunohistochemical and ultrastructural study

Granular cell basal cell carcinoma (BCC) is a rare histological variant of BCC. In this, the fifth reported case, a 67-year-old male with BCC located on the nose, light microscopy examination showed a tumour with the classical configuration of nodular BCC, in which most cells had finely granular eosinophilic cytoplasm. Ultrastructural observation showed numerous lysosome-like granules filling the cytoplasm of tumour cells, along with numerous well-formed pentalaminate desmosomes. Immunohistochemical profile (including positivity for keratins C 5.2 and AE 1 and for Leu-M1), together with the presence of cytoplasmic tonofilament bundles and desmosomes, are consistent with the proposed epithelial origin of granular cells in this tumour.

Histologic and immunohistochemical studies of granular cell tumors in seven dogs, three cats, one horse, and one bird

In a retrospective study, granular cell tumors in six dogs (Nos. 1-6), three cats (Nos. 1-3), one horse (No. 1), and one cockatiel (Nymphicus hollandicus) (No. 1) and a meningioma with a granular cell component in one dog (No. 7) were examined histologically and immunohistochemically. These tumors were identified by histologic examination of surgical biopsy specimens, except in the horse, in which the tumor was an incidental finding at necropsy. These diagnoses were initially made by more than one pathologist. Five of the six granular cell tumors in the dogs were in the oral cavity; one of these was in the maxillary gingiva of a 6-month-old puppy. The tumors in the cats were located in the tongue, vulva, and digit. The tumor in the horse was in the lung, and the tumor in the cockatiel was in the periocular tissue. Histologically, all granular cell tumors were characterized by oval to polygonal cells of various sizes. The cells had abundant, pale, eosinophilic cytoplasm with distinct intracytoplasmic granules, distinct cell margins, and mostly central nuclei. In the dogs, the gingival tumor had a large amount of collagen tissue, the tumor in the tongue had dilated blood vessels, and the maxillary tumor in the puppy was more cellular than the other tumors. The tumors in the cats were more anaplastic than the other tumors; one, located in the digit, was considered malignant. The granules in all of the tumors stained with periodic acid-Schiff and were diastase resistant. On staining with Luxol fast blue, the granules of all tumors stained different shades of pink, with the exception of the tumor in the tongue of a cat, which stained bluish green. Immunocytochemically, all tumors except the tumor in the cockatiel reacted against antibodies to vimentin. The granular cell tumor in the lung of the horse and the intracranial meningioma in a dog reacted to the antibody S-100 protein; the tumor in the horse reacted to neuron-specific enolase; tumors in two dogs (gingiva and skin) reacted to L-antitrypsin, and the maxillary tumor also reacted to lysozyme; the malignant tumor in the digit of a cat and the periocular tumor in the cockatiel reacted to muscle common actin and actin; the tumor in the cockatiel also reacted to desmin. Results of these immunocytochemical studies suggest that granular cell tumors, like tumors composed of rhabdoid cells, clear cells, and oncocytes, can have similar morphologic features but be of different cellular origins.

Calcifying and keratinizing ameloblastoma of the maxilla

A case is described of ameloblastoma of maxilla presenting with numerous calcified keratin pearls. The significance of cellular variation in relation to the behavioural potential of the ameloblastoma in general is briefly discussed.

Ameloblastic carcinoma. Report of an aggressive case and review of the literature

Odontogenic carcinomas of the jaws are classified as malignant ameloblastoma, ameloblastic carcinoma or primary intraosseous carcinoma. Because these lesions are extremely rare, microscopic diagnosis is difficult. An aggressive case of ameloblastic carcinoma of the mandible is presented. In spite of radical surgery and radiotherapy, the patient expired eight months following initial diagnosis. - A review of the literature seems to indicate that so called simple ameloblastomas rarely can dedifferentiate and metastasize following multiple inadequate surgical procedures. Although radical surgery is not necessary, local excision should be thorough. - Ameloblastic carcinoma and primary intraosseous carcinomas may be histogenetically similar. They are highly malignant tumours which should be treated aggressively. Metastasis is common and prognosis is poor.

Plexiform granular cell odontogenic tumor: unicystic variant

Plexiform granular cell odontogenic tumor of the mandible has recently been described. The cardinal histopathologic feature, as its name suggests, is a monophasic plexiform pattern of granular cells; the principal tumor in the differential diagnosis is granular cell ameloblastoma. Unlike the two previously reported cases of plexiform granular cell odontogenic tumor, which occurred as solid tumors in elderly men, the lesion reported here is a unicystic variant occurring in a middle-aged woman.

Peripheral ameloblastoma with clear cell differentiation

This report details a case of mandibular peripheral ameloblastoma having a clear cell component. The latter consisted of ovoid cells with vacuolated or clear cytoplasm and vesicular or pyknotic nuclei that may be disposed as discrete clusters or show direct transition from typical acanthomatous areas. Comparison of this lesion with other odontogenic and nonodontogenic tumors that contain clear cells is discussed in the context of the differential diagnosis.

Granular cell lesions of the jaws and oral cavity: a clinicopathologic, immunohistochemical, and ultrastructural study

A clinicopathological, immunohistochemical, and ultrastructural study of 44 oral granular cell lesions was performed. A total of 35 mucosal granular cell tumors, 4 granular cell ameloblastomas, 1 lichen planus with granular cell change, and 3 congenital epulides of the newborn were studied. Pseudoepitheliomatous hyperplasia was found to occur in only a minority of these cases. Immunohistochemically, the majority of granular cell lesions were uniformly positive for S-100 protein and focally positive for vimentin in one half of the cases, suggestive of origin from a Schwann cell or a precursor mesenchymal cell. Congenital epulis of the newborn and central odontogenic granular cell tumor were negative for S-100 protein, epithelial membrane antigen (EMA), and prekeratin, suggesting a mesenchymal origin for these lesions.