Biomedical subjects

C H Siar

Publications and source records attributed to C H Siar.

At least 37 records · Page 2Linked to original sources

PubMed1995

An immunohistochemical study of the lining epithelium of odontogenic keratocyst.

The lining epithelium of 15 cases of odontogenic keratocyst (OKC) was evaluated immunohistochemically. The peroxidase-antiperoxidase technique was applied to study the distribution of polyclonal keratin and S-100 protein while the indirect method was used to examine monoclonal vimentin and desmin reactivity. Consistent positive keratin staining was revealed in the lining epithelium of all 15 OKCs with additional intense staining in the stratum corneum. None of the cases showed vimentin or desmin reactivity within the lining epithelium elements. One of the 15 cysts studied showed positive S-100 protein staining in the nuclei of the lining epithelial cells. The pertinent literature on the immunophenotyping of the lining epithelium of OKC is reviewed.

Adolescent↗

PubMed1995

Peripheral odontogenic fibroma with clear cell odontogenic epithelium.

The clinical and histological features of the peripheral odontogenic fibroma are briefly outlined. A case arising from the attached lingual gingiva between the mandibular right permanent first molar and the second molar in a 67 year old Indian female is reported here. The unusual occurrence of marked clear cell differentiation within the odontogenic epithelial component, and histogenetic link to the clear cell rests of the dental lamina and surface epithelium are discussed.

Aged↗

PubMed1994

Aggressive (malignant?) epithelial odontogenic ghost cell tumour of the maxilla.

A case is described of ameloblastoma of the mandible presenting with multiple recurrences and subsequent extension to the maxilla with resultant transformation into an aggressive (malignant?) epithelial odontogenic ghost cell tumour. The latter is a rare, biologically virulent entity that affects mainly males, exhibits a preference for the maxilla and is histologically characterized by atypical malignant odontogenic epithelium associated with areas of ghost cell formation and varying amounts of dentinoid.

Adult↗

PubMed1993

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.

Adult↗

PubMed1993

'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.

Adult↗

PubMed1993

Patterns of expression of intermediate filaments and S-100 protein in desmoplastic ameloblastoma.

Seventeen cases of desmoplastic ameloblastoma were examined immunohistochemically. Immunoperoxidase techniques were applied for detection of keratin, desmin, vimentin and S-100 protein expression in these tumors. The tumor epithelium of desmoplastic ameloblastoma exhibited weak, focal, inconstant keratin staining, weak, variable expression of S-100 protein, desmin immunoreactivity of mild to moderate intensity and vimentin non-reactivity. The pertinent literature on the immunohistochemistry of ameloblastomas is briefly reviewed.

Adult↗

PubMed1993

Unusual granular cell odontogenic tumor. Report of two undescribed cases with features of granular cell ameloblastoma and plexiform granular cell odontogenic tumor.

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.

Adult↗

PubMed1993

Ameloblastoma in Malaysia--a 25-year review.

Four hundred and one cases of ameloblastoma of the jaw diagnosed in the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, between 1967 and 1991 have been analysed. There were 214 males and 187 females. Of these, 50.1% were Malays, 34.7% Chinese, 8.2% Indians and 7.0% other races. Seventy-two percent of patients were in the second, third and fourth decades of life (mean age: 30.8 years). Ninety-three percent of tumours occurred in the mandible and 6.5% in the maxilla. There were 337 cases of conventional ameloblastoma, 49 cases of the unicystic variant and four cases of peripheral ameloblastoma. The predominant histologic patterns were plexiform (34.2%), follicular (16.5%) and mixture of both (17.7%). Majority of the cases were conservatively treated by enucleation. Fifty-nine cases presented with recurrences. Present findings were generally compatible with regional serial studies reported from Thailand, Singapore and Japan.

Adolescent↗

PubMed1992

Immunohistochemical study of the distribution of S-100 protein in pleomorphic adenomas of minor salivary glands.

Twelve pleomorphic adenomas of minor salivary gland origin were examined for the distribution of S-100 protein, detected using the peroxidase-antiperoxidase (PAP) method. Strong S-100 protein immunoreactivity was noted in areas containing plasmacytoid cells, stellate and spindle cells against a myxochondroid or hyalinous stroma, and solid epithelial areas. Tubular and duct-like structures showed variable stainability. Stromal tissue and normal salivary glands were generally negative for S-100 protein. These findings were compared with those reported elsewhere.

Adenoma, Pleomorphic↗

PubMed1992

Denture hyperplasia and oncocytic metaplasia.

A case of denture hyperplasia of the upper labial sulcus with concomitant oncocytic metaplastic changes is described. The patient concerned is an elderly male wearing an ill-fitting upper full denture.

Aged↗

PubMed1992

Leiomyoma of the incisive papilla region: a case report.

Leiomyomas are benign neoplasms of smooth muscle origin. They represent rare entities in the oral cavity. A case arising from the incisive papilla region of a 3-month-old infant is described and the histogenesis as well as the biologic potential of this tumor are discussed.

Diagnosis, Differential↗

PubMed1991

Nasofacial zygomycosis.

Zygomycosis is an uncommon polymorphic fungal disease. One clinical subtype, nasofacial zygomycosis, is caused by infectious exposure to the organism Conidiobolus coronatus. A case affecting the nose and lips of a 42-year-old Malay man is reported here. The clinicopathologic features and management of this disease are described, and its differential diagnosis is discussed.

Adult↗

PubMed1991

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.

Cell Nucleus↗

PubMed1991

The combined epithelial odontogenic tumour in Malaysians.

The combined epithelial odontogenic tumour represents a hybrid lesion comprising primarily areas of adenomatoid odontogenic tumour intermixed with foci of calcifying epithelial odontogenic tumour. Five such cases retrieved from the files of the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, and four others from the existing literature were analysed. A mean age of 18.8 years, a female preponderance (66.7%) with a male to female ratio of 1:2 and predilection for the mandible (55.6%) were observed. All cases were treated by conservative surgery and the lack of recurrence confirmed the innocuous nature of this lesion.

Adolescent↗

PubMed1991

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.

Adult↗

PubMed1991

Kimura's disease: a case report.

The clinical and histologic features of Kimura's disease are briefly outlined. A case presenting as a subcutaneous nodule in the region of the angle of the right mandible of a 20-year-old male is presented. The relationship of this disease to angiolymphoid hyperplasia with eosinophilia is discussed.

Adult↗

PubMed1990

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.

Ameloblastoma↗

PubMed1990

Atypical peripheral ameloblastoma of the palate.

Clinical, radiological and histological characteristics of the peripheral ameloblastoma are briefly outlined. A case found occurring in the palate and presenting with atypical histological features is reported. The differential diagnosis of this lesion, its treatment and histogenesis are discussed.

Adult↗