MyMedR

Squamous cell carcinoma of the oral mucosa in Malaysia--any change?

Ng KH, Siar CH, Ramanathan K, Murugasu P, Chelvanayagam PI

Southeast Asian J. Trop. Med. Public Health, 1985 Dec;16(4):602-6.

The prevalence rate of 749 cases of oral squamous cell carcinomas (SCC) recorded between 1978-1984 was studied. Results showed that the Indians formed the dominant group (63.8%) followed by the Malays (19.6%) and Chinese (16.6%). The peak incidences were generally located between the sixth and eighth decades. Only in the Chinese group a male preponderance was noted. In the Indians, the buccal mucosa was the most prevalent site; in the Malays and Chinese males, the gingiva and alveolus; and the Chinese female, the tongue. In all three groups, the well-differentiated SCC was the commonest type and the poorly differentiated least common.

Fulltext Conservative surgical management of ameloblastoma of the mandible--report on three cases

Foo GC, Siar CH, Ling KC, Chin CT

Med J Malaysia, 1983 Dec;38(4):334-8.

PMID: 6599995

Features of the typical ameloblastoma of the mandible are outlined. Three cases managed by conservative surgical treatment maintaining the continuity of the mandible are described. The factors taken into consideration when instituting this method of treatment are discussed. Results obtained are encouraging.

Fulltext Clinical statistics of the adenomatoid odontogenic tumour in Malaysia (1968-1986)

Siar CH, Ng KH, Murugasu P

Med J Malaysia, 1987 Dec;42(4):284-9.

PMID: 3331408

The records of the Division of Stomatology were reviewed for the incidence of adenomatoid odontogenic tumour diagnosed between 1968 and 1986. Forty-five cases were found. The prevalence of this tumour according to their age, sex, site and its distribution in the various states in Malaysia are reported. Many features were similar to previous reports of this entity. However the incidence of AOT appears to be higher among the Indians and lower in the Chinese population. It is suggested that this feature may be peculiar to Malaysians.

Fulltext Teeth in osteogenesis imperfecta: a light microscopic study

Siar CH

Med J Malaysia, 1986 Jun;41(2):161-5.

PMID: 3821613

The light microscopic features of the dentine in three teeth from two cases of osteogenesis imperfecta (OJ) are presented. Results show that teeth in OJ distinctively have a more uniform and tubular mantle dentine, and a characteristic laminated circumpulpal dentine formed by distorted incremental bands alternating with parallel rows of interglobular dentine and interrupted by comet-shaped vascular canals. The study indicated that in the absence of overt OJ features, the changes in dentine alone are sufficiently characteristic to establish such a diagnosis.

Fulltext Congenital fibrous epulis: a case report

Majid ZA, Siar CH, Ling KC

Med J Malaysia, 1986 Jun;41(2):179-82.

PMID: 3821617

An unusual case of fibrous epulis in a newborn is presented. The clinical appearance, histological features and method of treatment are described. A short review of the literature is also included.

Fulltext Cervical toxoplasma lymphadenitis: report of a case

Siar CH, Foo GC

Med J Malaysia, 1984 Dec;39(4):306-10.

PMID: 6544939

Toxoplasmosis is a parasitic infection of worldwide distribution. It is caused by an obligate intracellular parasite, Toxoplasma gondii. The commonest form of this disease is the acquired simple lymphadenopathy. Such a case is described and the clinicopathological significance of the disease is discussed.

Fulltext Hyaline cells in salivary gland tumours

Ng KH, Siar CH

Med J Malaysia, 1986 Sep;41(3):213-9.

PMID: 2444865

The morphology, incidence and distribution of hyaline cells in ten cases each of pleomorphic adenoma, adenoid cystic carcinoma, adenocarcinoma and mucoepidermoid tumour were studied by conventional light microscopy. Results showed that the hyaline cells were identified in 60% of pleomorphic adenoma and in 20% of mucoepidermoid tumours, but were absent in adenoid cystic carcinoma and adenocarcinoma. Relative area estimation of hyaline cells in pleomorphic adenomas showed that this may range from 2.2% to 30.4% of the total tumour area. The usefulness of the hyaline cell as a diagnostic criteria in distinguishing between some of the salivary gland tumours was also discussed.

Parenchyma-stromal interleukin-1 alpha and interleukin-6 overexpressions in ameloblastoma correlate with the aggressive phenotype

Goh YC, Chan SW, Siar CH

Malays J Pathol, 2019 Dec;41(3):303-311.

PMID: 31901915

INTRODUCTION: Ameloblastoma is a benign but locally invasive odontogenic epithelial neoplasm with a high recurrence rate after treatment. The two main subsets encountered clinically are unicystic (UA) and solid/multicystic ameloblastoma (SMA). Currently neoplastic progression of many tumour types are believed to be related to parenchyma-stromal cell-cell interactions mediated by cytokines notably interleukins (IL). However their roles in ameloblastoma remain ill-understood.

MATERIALS AND METHODS: Thirty-nine formalin-fixed paraffin-embedded ameloblastoma cases comprising unicystic ameloblastoma (n=19) and solid/multicystic ameloblastoma (n=20) were subjected to IHC staining for IL-1α, IL-1β, IL-6 and IL-8. A semi-quantitative method was used to evaluate the expression levels of these cytokines according to cell types in the tumoural parenchyma and stroma.

RESULTS: Major findings were upregulations of IL-1α and IL-6 in SMA compared to UA. Both cytokines were heterogeneously detected in the tumoural parenchyma and stroma. Within the neoplastic epithelial compartment, IL-1α expression was more frequently detected in PA-like cells in UA whereas it was more frequently encountered in SR-like cells in SMA. IL-6 demonstrated higher expression levels in the stromal compartment of SMA. IL-1β and IL-8 were markedly underexpressed in both tumour subsets.

CONCLUSIONS: Overexpression of IL-1α in SMA suggests that this growth factor might play a role in promoting bone resorption and local invasiveness in this subtype. The expression levels of IL-1α and IL-6 in three cellular localizations indicate that parenchymal-stromal components of ameloblastoma interact reciprocally via IL-1α and IL-6 to create a microenvironment conducive for tumour progression.

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

Siar CH, Ng KH

J Laryngol Otol, 1994 Mar;108(3):269-71.

PMID: 8169519

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.

A clinicopathological and immunohistochemical study of the calcifying epithelial odontogenic tumour (Pindborg tumour) in Malaysians

Ng KH, Siar CH

J Laryngol Otol, 1996 Aug;110(8):757-62.

PMID: 8869610

We reviewed the clinicopathological characteristics of 13 cases of calcifying epithelial odontogenic tumour (CEOT) (Pindborg tumour) diagnosed in the Division on Stomatology, Institute for Medical Research, Kuala Lumpur, over a 29-year period. There were eight female and five male patients. These consisted of eight (61.5 per cent) Malays, three (23.1 per cent) Chinese, one (7.7 per cent) Indian and one (7.7 per cent) Melanau. Their ages at presentation ranged from 19-61 years (mean age, 31.8 years). There were 12 central and one peripheral CEOT. Of these, 76.9 per cent of cases were located in the maxilla, the remaining in the mandible. The commonest clinical diagnosis was a dentigerous cyst (66.7 per cent). Enucleation was the main mode of treatment. Histologically, sheets and strands of polyhedral epithelial cells containing eosinophilic, homogeneous globules with Liesegang rings were observed. One case also showed extensive calcification and clear cell differentiation. Immunohistochemistry revealed a variable keratin staining of the CEOT epithelium, confirming its heterogeneity.

Calcifying and keratinizing ameloblastoma of the maxilla

Siar CH, Ng KH

J Laryngol Otol, 1991 Nov;105(11):971-2.

PMID: 1722237

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.

Atypical peripheral ameloblastoma of the palate

Siar CH, Ng KH, Ngui CH, Chuah CH

J Laryngol Otol, 1990 Mar;104(3):252-4.

PMID: 2341785

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.

Morphometric analysis of epithelial components and dentinoid formation in non-neoplastic calcifying odontogenic cyst

Ng KH, Siar CH

J Nihon Univ Sch Dent, 1995 Sep;37(3):156-62.

PMID: 7490609

Calcifying odontogenic cysts (COCs) represent a group of lesions that may be broadly classified into two main entities: cysts and neoplasms. In the present study 30 non-neoplastic cystic COCs were examined by a quantitative histological method in an attempt to calibrate the relative distribution of the type of epithelial lining, intensity of ghost cell formation and the amount of dentinoid present. The results showed that there are two main types of cystic COC: an odontoma-producing type and a non-odontoma-producing variant. Morphologically, tooth-like structures were a valid distinguishing feature, while morphometrically the odontoma-producing variant showed a greater amount of luminal and mural dentinoid as well as luminal ghost cells. Demographic analysis also revealed that the odontoma-producing COC occurred in younger patients and showed an even sex distribution, whereas the non-odontoma-producing type was seen in older patients and showed a predilection for females. Both subtypes were more prevalent in the Chinese population and occurred preferentially in the maxilla.

An immunohistochemical study of the lining epithelium of odontogenic keratocyst

Siar CH, Ng KH

J Nihon Univ Sch Dent, 1995 Sep;37(3):163-9.

PMID: 7490610

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.

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

Siar CH, Ng KH

J Nihon Univ Sch Dent, 1993 Jun;35(2):134-8.

PMID: 7692017

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.

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

Siar CH, Ng KH

J Nihon Univ Sch Dent, 1993 Jun;35(2):104-8.

PMID: 7692015

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.

A clinicopathologic study of odontomas: Malaysian findings

Ng KH, Siar CH

J Nihon Univ Sch Dent, 1997 Dec;39(4):171-5.

PMID: 9476429

This report reviews the clinicopathologic characteristics of 104 cases of odontomas diagnosed in the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, over a 29-year period (1967-1995). The results showed no real predilection in terms of sex (M:F ratio, 1:1), race (45.2% Malays, 40.4% Chinese, 10.6% Indians and 3.8% other races) or site (maxilla:mandible ratio, 1: 1.04) distribution. The mean age at presentation was 24.8 years and the age range was 3-74 years. There were 102 intraosseous and 2 extraosseous odontomas. Swelling was the most common presenting complaint. The majority of cases (81.9%) were clinically diagnosed as odontomas. The treatment of choice was surgical enucleation. Compound (43.3%) and complex (35.5%) odontomas were the two most common histological types encountered. The present findings correlate favorably with reported studies from other geographic areas.

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

Siar CH, Ng KH

J Nihon Univ Sch Dent, 1992 Jun;34(2):96-105.

PMID: 1380072

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.

Clinicopathological study of peripheral odontogenic fibromas (WHO-type) in Malaysians (1967-95)

Siar CH, Ng KH

Br J Oral Maxillofac Surg, 2000 Feb;38(1):19-22.

PMID: 10783442

Analysis of case records of 46 patients with peripheral odontogenic fibroma (1967-95) diagnosed in the Division of Stomatology, Institute for Medical Research, Kuala Lumpur, disclosed a relatively young age of onset (mean, 32.2 years; range 5 months-64 years; peak incidence second decade of life), a slight female preponderance (M:F ratio 1:1.3), no racial predilection, a slight bias towards location in the mandible (52%) and a wide histomorphological range. All cases were treated by simple excision. Follow-up records were generally not available, so we do not know what the recurrence rate is.

Desmoplastic variant of ameloblastoma in Malaysians

Ng KH, Siar CH

Br J Oral Maxillofac Surg, 1993 Oct;31(5):299-303.

PMID: 8218083

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.

Displaying publications 1 - 20 of 91 in total