Aberrant expression of cyclin A and cyclin B1 proteins in oral carcinoma

Cyclins play an important role in regulating the passage of dividing cells through critical checkpoints in the cell cycle. Aberrant expression of cyclin proteins has been found in a number of human cancers, including carcinomas of the head and neck, where amplification of the cyclin D1 gene is a common finding. The objective of this study was to examine cell cycle kinetics in oral carcinomas by determining the expression of the S phase protein cyclin A and the M phase protein cyclin B1. Routinely processed tissue sections of 50 oral squamous cell carcinomas from the floor of the mouth were stained by immunohistochemistry for cyclin A, cyclin B1 and Ki-67 proteins. Ten specimens of normal epithelium from the floor of the mouth were used as controls. The number of cells showing nuclear staining for cyclin A, cyclin B1 and Ki-67 proteins was determined by computer image analysis. There were 17 well-differentiated, 25 moderately differentiated and 8 poorly differentiated tumours. Mean counts for cyclin A (29.50+/-4.10, mean+/-95% CI), cyclin B1 (2.05+/-0.30) and Ki-67 (49.46+/-5.91) proteins in the carcinomas were significantly higher than counts for the normal epithelial controls (cyclin A: 9.30+/-1.72; cyclin B1: 1.01+/-0.36; Ki-67: 17.40+/-4.17). For cyclin A, cyclin B1 and Ki-67, mean staining scores for all tumour grades were significantly higher than controls. There was a strong correlation between Ki-67 and cyclin A scores in all tumour groups (r2=0.68); however, the correlations between cyclin B1 and cyclin A scores (r2=0.35) and between cyclin B1 and Ki-67 scores (r2= 0.39) were weak. We conclude that there is overexpression of cyclin A and cyclin B1 proteins in oral carcinoma. Furthermore, the poor correlations for cyclin B1 scores with other cell cycle indices suggest that there may be aberrant cell cycle progression at the G2/M checkpoint in oral carcinomas.

Circadian variation in the expression of cell-cycle proteins in human oral epithelium

At the tissue level, there is experimental and clinical data to suggest a cytokinetic coordination of the cell cycle with a greater proportion of cycling cells entering S-phase and mitosis at specific times of the day. The association of certain cell-cycle proteins with defined events in the cell cycle is well established and may be used to study the timing of cell-cycle phases over 24 hours. In this study oral mucosal biopsies were obtained from six normal human volunteers at 4-hour intervals, six times over 24 hours. Using immunohistochemistry, the number of positive cells expressing the proteins p53, cyclin-E, cyclin-A, cyclin-B1, and Ki-67 was determined for each biopsy and expressed as the number of positive cells per mm of basement membrane. We found a statistically significant circadian variation in the nuclear expression of all of these proteins with the high point of expression for p53 at 10:56 hours, cyclin-E at 14:59 hours, cyclin-A at 16:09 hours, cyclin-B1 at 21:13 hours, and Ki-67 at 02:50 hours. The circadian variation in the nuclear expression of cyclins-E (G1/S phase), -A (G2-phase), and -B1 (M-phase) with a normal physiological progression over time suggests a statistically significant circadian variation in oral epithelial cell proliferation. The finding of a circadian variation in the nuclear expression of p53 protein corresponding to late G1 is novel. This information has clinical implications regarding the timing of chemotherapy and radiotherapy.

Bilateral dentigerous cysts--report of an unusual case and review of the literature

Dentigerous cysts are the most common developmental cysts of the jaws, most frequently associated with impacted mandibular third molar teeth. Bilateral dentigerous cysts are rare and occur typically in association with a developmental syndrome. The reported occurrence of bilateral dentigerous cysts in the absence of a syndrome is rare and, to date, only 11 cases have been described. Here, we report a case of bilateral nonsyndromic, dentigerous cysts and review the literature for this unusual finding.

Infantile desmoid-type fibromatosis in an Akita puppy

A 10-week-old Akita puppy was evaluated for a reported umbilical hernia. Repair of the hernia had been attempted three times prior to referral. A defect in the ventral abdominal wall with an associated soft-tissue mass was identified on abdominal radiographs. Exploratory surgery was performed; the mass was resected and the abdominal wall defect was repaired. Histopathological evaluation of the mass was consistent with infantile desmoid-type fibromatosis.

Reduced levels of the cell-cycle inhibitor p27Kip1 in epithelial dysplasia and carcinoma of the oral cavity

Recent studies have shown that the cyclin-dependent kinase (cdk) inhibitors play important roles in cell cycle progression in normal cells. Alterations in the cdk inhibitors also appear to be important in cancer development in a number of human tumors. p27Kip1 is a member of the CIP/KIP family of cdk inhibitors that negatively regulates cyclin-cdk complexes. Reduced levels of p27Kip1 protein have been identified in a number of human cancers, and in some cases reduced p27Kip1 is associated with an increase in proliferative fraction. In the present study, we examined p27Kip1 protein by immunohistochemistry in 10 normal and 36 dysplastic epithelia and in 8 squamous cell carcinomas from one anatomical site within the oral cavity, the floor of the mouth. Proliferative activity was assessed in serial sections by determining the expression of the cell cycle proteins Ki-67 and cyclin A. p27kip1 protein was significantly reduced in oral dysplasias and carcinomas compared with that in normal epithelial controls. In addition, there was a significant reduction in p27Kip1 protein between low- and high-grade dysplasias, suggesting that changes in p27Kip1 expression may be an early event in oral carcinogenesis. There was increasing expression of Ki-67 and cyclin A proteins with increasingly severe grades of dysplasia compared with normal controls. Although there was a strong correlation between Ki-67 and cyclin A scores (r2= 0.61) for all categories of disease, there was a weak negative correlation between Ki-67 and p27Kip1 levels (r2 = 0.29) and between cyclin A and p27Kip1 levels (r2 = 0.25). In conclusion, this study has found that a reduction in the proportion of cells expressing p27Kip1 protein is frequently associated with oral dysplasia and carcinoma from the floor of the mouth. Furthermore, reductions in p27Kip1 levels are associated with increased cell proliferation, although other changes likely contribute to altered cell kinetics during carcinogenesis at this site.

Scoring oral mucositis

Oral mucositis is a common, dose limiting and potentially serious complication of both radiation and chemotherapy. Both these therapies are non-specific, interfering with the cellular homeostasis of both malignant and normal host cells. An important effect is the loss of the rapidly proliferating epithelial cells in the oral cavity, gut and in the bone marrow. Within the mouth, the loss of these cells leads to mucosal atrophy, necrosis and ulceration. Although post-treatment healing is generally uneventful, severe mucositis can be life threatening, especially if complicated by dehydration or secondary infection. Accurate and reproducible evaluation of oral mucositis is important in order to monitor patient toxicity during therapy, to document the toxicity of conventional therapy and to critically assess the effects of alternative therapies. A number of oral toxicity scoring systems have been described, but direct comparisons have rarely been undertaken and little data exist regarding inter- and intra-user reliability. This paper reviews a number of oral mucositis scoring systems that are commonly used and will also discuss, briefly, the biological basis of its development and management.

The action of perchlorate on malignant-hyperthermia-susceptible muscle

To better understand the altered skeletal muscle excitation-contraction (E-C) coupling that occurs in malignant hyperthermia, we have examined the potentiating actions of perchlorate in intact muscle fiber bundles, isolated sarcoplasmic reticulum (SR) vesicles, and the purified ryanodine receptor/Ca2+ release channel (RyR) isolated from malignant-hyperthermia-susceptible (MHS) and normal porcine muscle. The concentration of perchlorate that half-maximally potentiated twitch tension (2.5-3.5 mM) was not significantly different for MHS and normal muscles. The effect of perchlorate on fractional twitch force was significantly greater for normal than for MHS muscle, although the absolute twitch potentiation was similar for both muscle types. The K-contracture threshold of MHS muscle bundles is significantly lower than that of normal bundles; perchlorate shifted the K-contraction activation curves of both MHS and normal muscle bundles to lower K+ concentrations. Perchlorate both increased ryanodine binding to MHS and normal SR vesicles and increased single-channel open probability of the purified MHS and normal RyR. In both cases, the percentage increase was greater for normal than for MHS preparations; however, the absolute increase in activity was not different for MHS and normal RyR indicating that there is no difference in the perchlorate sensitivity of MHS and normal SR Ca2+ release channels. Thus, the greater absolute responses of the MHS Ca2+ release channel in the presence of perchlorate is likely to be due to the greater basal activity of the MHS release channel and does not reflect an underlying defect in the site of action of perchlorate on the MHS skeletal muscle Ca2+ release channel.

Patterns of p53 and Ki-67 protein expression in epithelial dysplasia from the floor of the mouth

Oral squamous cell carcinoma develops through a series of precancerous stages manifested at the microscopic level as epithelial dysplasia. Mutation of the p53 tumour suppressor gene is thought to be an important component of oral carcinogenesis. p53 regulates cell proliferation and DNA repair by inhibiting the cell cycle at G1/S; loss of p53 function may therefore lead to aberrant cell kinetics. To date, no studies have examined the relationship between p53 protein and alterations in cell kinetics in oral epithelial dysplasia from a single anatomical site. Serial sections were studied from 40 routinely processed biopsy specimens of epithelial dysplasia from the floor of the mouth. The expression of p53 protein was determined by immunohistochemistry and cell proliferation was studied by immunostaining for the cell cycle-dependent protein Ki-67. The number of positive cells per millimetre of basement membrane was determined using computer image analysis and compared with site-matched normal controls. The mean p53 labelling index (LI) in normal mucosa was low, 3.48 +/- 0.92 [mean +/- 95 per cent confidence interval (CI)], and increased sharply in the transition from mild (42.49 +/- 21.71) to moderate (104.86 +/- 51.39) epithelial dysplasia. The mean p53 LI for severe dysplasia was 119.09 +/- 56.50. Differences were also observed in the distribution of p53-positive cells between grades of dysplasia, with the development of compact p53-positive foci in severe dysplasia. Mean proliferative indices, as determined by Ki-67 expression, were significantly associated with grade of epithelial dysplasia. Furthermore, there was a significant correlation between p53 LI and Ki-67 score (r2 = 0.37, P = 0.01). It is concluded that altered p53 protein expression is probably an early event in oral carcinogenesis in the floor of the mouth and is associated with dysregulation of cell proliferation at this site.

Absence of Helicobacter pylori DNA in salivary lymphoepithelial lesions

Helicobacter pylori is a common cause of chronic gastritis and has been implicated as the main agent responsible for the development of lymphomas of mucosa associated lymphoid tissue (MALT) in the stomach. An uncommon cause of salivary gland swelling is salivary lymphoepithelial lesion (SLEL), which shows histological features of acquired MALT and is associated with the development of MALT-type lymphomas. Since H. pylori has been identified in the oral cavity, we hypothesised that this organism might act as a potential antigen for the development of MALT in salivary glands. Routinely processed biopsies of 20 SLEL were screened for H. pylori DNA using a sensitive two-stage PCR technique to amplify the 16S ribosomal RNA gene. Immunoglobulin heavy chain gene monoclonality was determined by amplifying the VDJ gene using a nested PCR technique. All SLEL had histological features of organised MALT and 14 cases showed Ig heavy chain gene monoclonality consistent with MALT lymphoma. None of the SLEL contained H. pylori DNA. In contrast to the putative role of H. pylori as an antigenic stimulus in gastric MALT lymphomas, it appears not to play a role locally in the development of MALT or MALT lymphomas of the salivary gland.

High-grade papillary cystadenocarcinoma of the tongue

AIMS

Salivary gland tumours of the tongue are rare. The most common type is low-grade mucoepidermoid carcinoma followed by adenoid cystic carcinoma. Papillary cystadenocarcinoma of salivary glands are uncommon lesions with low-grade mucoepidermoid carcinoma followed by adenoid cystic carcinoma. Papillary cystadenocarcinoma of salivary glands are uncommon lesions with low-grade histological and clinical features. We report a high-grade papillary cystadenocarcinoma in an 80-year-old man who presented with a tongue mass and metastatic disease in the neck.

METHODS AND RESULTS

He was treated with partial glossectomy and bilateral neck dissection but developed local and regional recurrences 6 months later. The tumour had a prominent cystic appearance and had areas of necrosis. The cyst lumen was occupied by numerous papillae lined by pseudostratified columnar cells with a high nuclear-cytoplasmic ratio. The cytoplasm was eosinophilic, the nuclei were pleomorphic and exhibited irregular nuclear membranes, vesicular chromatin and prominent eosinophilic nucleoli. The mitotic activity was high and there were occasional abnormal mitotic figures. Metastatic carcinoma was present in four lymph nodes. The differential diagnosis of this unusual lesion includes cystadenoma, salivary duct carcinoma and metastases.

CONCLUSIONS

This case and a review of the literature indicates that papillary cystadenocarcinomas of salivary gland origin exhibit a wider morphologic spectrum than described in the latest World Health Organization (WHO) classification which defines these lesions as low-grade neoplasms.

Oral squamous cell carcinoma: new insights

Squamous cell carcinoma is the most common form of oral cancer, and causes more deaths than any other oral disease. Dentists and dental auxiliaries must know the clinical, etiologic, pathogenetic and prognostic features of squamous cell carcinoma to ensure appropriate screening and diagnosis of the patient. It is now recognized that cancers are genetic diseases, which arise from inherited genetic factors and exposure to exogenous carcinogens that alter the DNA of cells. Increasingly, the genetic events that contribute to the development of cancers at many sites within the body are being identified, and the complex series of genetic steps required for fully-developed neoplasia to arise in the oral cavity are being better characterized. This article reviews recent advances in the understanding of the etiology and pathogenesis of oral carcinoma, including the involvement of various oncogenes, tumor suppressor genes and viruses.

Solitary angiokeratoma of the oral cavity

Angiokeratoma is a rare, cutaneous disorder that typically occurs at multiple sites and is often associated with a number of metabolic disorders. Although solitary cutaneous forms have been reported, to date localized lesions within the oral cavity have not been described. We report on an 82-year-old man with a history of squamous cell carcinoma of the ear and scalp who also had a solitary pigmented lesion of the oral cavity. Excisional biopsy of the buccal mucosal lesion showed features consistent with angiokeratoma. We report the first intra-oral solitary angiokeratoma and review the clinical and pathologic features of this unusual condition.

Oral lymphoma in HIV infection

OBJECTIVE

This study reports the main clinical and histological features, and the treatment and outcomes of six HIV-associated oral lymphomas.

SUBJECTS

During the period 1991-1995, six cases of lymphoma presenting in the oral cavity were diagnosed in this clinic. All six patients were men ranging in age from 36 to 62 years with CD4 counts below 100 cells mm-3.

RESULTS

In five patients, oral lymphoma was the first AIDS defining disease. Four lesions occurred on the gingiva, one on the palate and one on the tongue. The duration of symptoms prior to presentation ranged from 2 weeks to 14 months. In all but one patient, the lesions presented as red, exophytic masses and were diagnosed clinically as Kaposi's sarcoma. None of the five lesions presenting on the palate or gingiva showed radiographic evidence of bone destruction. Metastatic work-up failed to diagnose lymphoma elsewhere in the five cases where this was performed. Histological diagnoses included two small, non-cleaved (Burkitt's type) lymphomas, two immunoblastic lymphomas, one large cell lymphoma and one small, non-cleaved (non-Burkitt's) lymphoma.

CONCLUSION

These findings highlight the uncommon clinical presentation of this disease and despite its relative rarity, demonstrate the need to maintain a high degree of suspicion in any unusual oral lesion in this group of patients.

Differential expression of bcl-2 and bax in squamous cell carcinomas of the oral cavity

The bcl-2 oncogene is a member of a family of genes encoding for proteins which regulate apoptosis (programmed cell death). Recent evidence suggests that the bcl-2 protein is regulated by a homologous protein bax which counteracts its effects and promotes apoptosis. Overexpression of bcl-2 has been reported in a number of human cancers, although correlations with tumour differentiation and clinical outcome are conflicting and depend on tumour type and site. We studied bcl-2 and bax protein expression in adjacent serial sections of 30 squamous cell carcinomas of the oral cavity and correlated this with tumour differentiation. Examination of normal epithelium showed bcl-2 expression confined to basal keratinocytes and dendritic cells. The bax immunostaining was seen throughout the thickness of the epithelium but was most intense in the suprabasal cells. Overall, moderate or marked immunostaining for bcl-2 was identified in 18/30 (60%) carcinomas and for bax in 19/30 (63%) tumours. The bcl-2 immunoreactivity was strongest in the poorly differentiated carcinomas where 6/7 (86%) showed strong staining. By contrast, bax immunoreactivity was strongest in the well-differentiated carcinomas with 8/11 (72%) staining strongly. In the well-differentiated tumour islands, there was inverse topographic distribution of bcl-2 and bax, with both proteins showing a pattern that recapitulated normal epithelium. Upregulation of bcl-2 protein was identified in dysplastic epithelium adjacent to invasive tumour and in many cases there was reduced bax immunostaining. These results suggest that alterations of bcl-2 and bax may play a role in the development of squamous cell carcinoma. Furthermore, disturbances of protein expression in dysplastic epithelium suggest a role in the early stages of epithelial carcinogenesis.

High prevalence of B-cell monoclonality in labial gland biopsies of Japanese Sjögren's syndrome patients

Patients with Sjögren's syndrome (SS) have an increased risk of developing malignant lymphoma. Although some clinical parameters may herald the imminent onset of lymphoma, few reliable markers are available to predict the progression to a malignant lymphoproliferative disorder. Although there are a number of immunological and serologic features that distinguish SS in Japanese patients, in common with their Western counterparts these patients also have an increased risk of lymphoid neoplasia. Recently we have reported finding a high prevalence (17%) of monoclonal immunoglobulin (Ig) heavy chain gene rearrangements in labial salivary gland (LSG) biopsies of Western SS using the polymerase chain reaction (PCR). In many cases this finding was predictive for the subsequent development of lymphoma. In this study LSG from 50 Japanese SS patients were examined for Ig heavy chain gene monoclonality using PCR to amplify the VDJ region and identified in 7 of 50 (14%) cases. Three patients with monoclonality in the LSG had evidence of lymphoma at extra-salivary gland sites. In one of these the diagnosis of lymphoma was made subsequent to lip biopsy. In the other two lymphoma at extra-salivary gland sites was diagnosed prior to LSG biopsy. The results suggest that the prevalence of Ig heavy chain gene monoclonality in LSG of Japanese SS patients is similar to that in the West, and that neoplastic cells can be identified in LSG as a component of more widely disseminated disease.

Topical steroid therapy in oral lichen planus: review of a novel delivery method in 24 patients

Lichen planus is a chronic mucocutaneous disorder of unknown etiology. The natural progression of oral lichen planus (OLP) is long and can extend over a number of years. Although many patients with OLP remain asymptomatic, some experience periods of marked inflammation with breakdown of the lesions, and require treatment. Corticosteroids are the mainstay of treatment for oral lesions, but delivery to affected mucosal sites can be problematic. The purpose of this study was to retrospectively review the results of topical steroid therapy in a group of patients with OLP, using a novel delivery method. The records of 33 patients with biopsy-proven OLP were reviewed and the relevant clinical features were noted at minimum review intervals of one, six and 12 months. Of this group, 24 patients had been treated using a standardized treatment protocol consisting of a corticosteroid ointment applied topically to mucosal lesions using cloth strips. Gingival lesions were treated using a steroid preparation in an adhesive paste. Nine patients remained asymptomatic and were not treated. In the treated group, 14/24 (58 per cent) of patients showed an improvement in symptoms by one month. The remainder showed no change or a worsening of their symptoms. Repetition of the treatment protocol resulted in improvement in all the non-responders, and by one year 23 of 24 (96 per cent) of the patients had experienced improvement or control of their symptoms. Long-term failure to control the symptoms in the single non-responding case was related to poor patient compliance. Results from this study show that a novel delivery method and treatment protocol for the application of topical steroids onto lesional mucosa is useful for the symptomatic control of oral lichen planus.

Lymphoma in Sjögren's syndrome. From histopathology to molecular pathology

A number of autoimmune diseases predispose to the development of neoplasia. A particularly well-recognized association is the development of lymphoma in Sjögren's syndrome. Although this risk has been estimated to be 44 times that of the general population, few reliable prognostic indexes exist for individual patients. Recent advances in molecular biology have improved our understanding of Sjögren's syndrome and permitted better characterization of the generalized lymphoproliferation associated with the condition. This article reviews the histopathology of the major and minor salivary gland lesions of Sjögren's syndrome and discusses advances in molecular biology that have permitted more accurate prediction of lymphoma development in this group of patients.

B-cell monoclonality in salivary lymphoepithelial lesions

It is well recognised that lymphoma may arise in a lymphoepithelial lesion of the salivary glands. Although the histological features of this lesion are well described, it is not clear what proportion contain monoclonal populations of lymphocytes at outset. In this study, 22 routinely processed lymphoepithelial lesions in parotid glands were examined for B-cell monoclonality using the polymerase chain reaction (PCR) to amplify the immunoglobulin heavy chain gene and using in situ hybridisation or immunohistochemistry to detect kappa or lambda light chain restriction. B-cell monoclonality was identified in 17/22 (77.3%) cases using a combination of the three methods. The detection rate for B-cell monoclonality was highest using PCR with 15/22 (68%) cases containing monoclonal immunoglobulin heavy chain gene rearrangements. In a proportion of cases the results of in situ hybridisation and immunohistochemistry were judged to be inadequate and this was probably a reflection of variations in fixation. In 7 patients, sequential biopsies were available from other sites and 6 of these also showed B-cell monoclonality. The results confirm the high prevalence of B-cell monoclonality in lymphoepithelial lesions of the major salivary glands. Furthermore, these results would suggest that PCR is a more reliable technique to identify B-cell monoclonality in routinely processed lymphoepithelial lesions compared to in situ hybridisation and immunohistochemistry.

Porcine malignant hyperthermia: genotype and contractile threshold of immature muscles

We investigated whether malignant hyperthermia (MH)-related contractile abnormalities, such as lowered contractile threshold, were expressed in MH-susceptible (MHS) immature muscles and myotubes. Muscles from neonatal piglets homozygous for Arg615 (normal) or for Cys615 (MHS) ryanodine receptor alleles, and heterozygotes were used. Intact cell bundles from piglet muscles generally were similar in contractile properties to adult muscles of the same genotype. Thresholds for K contractures in normal, heterozygous, and MHS piglet muscles (40 mmol/L, 25 mmol/L and 15 mmol/L K+, respectively) differed significantly. Cultured myotubes were subjected to a series of square pulses of varying strengths (-50 to +50 mV) and durations (25-300 ms) using whole cell patch-clamp techniques. Threshold for contraction differed significantly among the three genotypes, for example, with 300 msec pulses thresholds were -6.9 +/- 0.9, -12.4 +/- 1.6, and -22.6 +/- 2.6 mV for normal, heterozygous and MHS myotubes, respectively. Thus a significantly lower than normal threshold for contraction was expressed in MHS and heterozygous piglet muscles and myotubes. Further, these developmentally immature preparations are likely to express other differences characteristic of adult MHS muscles, and thus provide suitable preparations for clinically relevant studies of MH-related cellular abnormalities.

Verrucous carcinoma of the mouth

Verrucous carcinoma is a slow-growing, well differentiated carcinoma that is chiefly exophytic but can invade and destroy oral tissues. It typically presents as an extensive, white, warty lesion of the buccal mucosa or mandibular gingiva, although it also occurs at other sites. Diagnosis can be difficult, with repeat biopsies being needed in some cases. The persistent nature of the condition can make management difficult and the possibility of recurrent disease is high.

High frequency of light chain restriction in labial gland biopsies of Sjögren's syndrome detected by in situ hybridization

A well-recognized complication of Sjögren's syndrome (SS) is the development of malignant lymphoma, with a risk 44 times that of the general population. Although a few clinical signs may indicate the onset of lymphoma, there are few reliable laboratory markers which predict the development of neoplasia. A non-isotopic in situ hybridization technique has been applied to routinely processed labial salivary gland (LSG) biopsies of patients under investigation for SS. Serial section of 70 LSGs were examined for a kappa and gamma immunoglobulin light chain mRNA using digoxigenin-labelled oligonucleotide probes. As controls, 39 biopsies from non-SS-associated sialadenitis were also examined. Sections were analysed using computer-assisted quantification to determine the percentage of kappa-expressing cells in each case. The range of kappa expression in the SS group was 24.1-93.4 percent and in the non-SS group 48.3-75.4 per cent. Light chain restriction was found in 13/70 (18.6 percent) cases from the SS group but in no cases of the control group. Of the SS cases showing restriction, 4/13 (30.7 percent) have subsequently developed extrasalivary gland lymphoma. Two patients not showing light chain restriction in LSG have subsequently developed lymphoma. The positive predictive value of this test to identify patients at risk of lymphoma was 30.7 percent with a detection rate (sensitivity) of 66.7 percent and a false-positive rate of 14.1 per cent(specificity 85.9 percent). This study has identified a high prevalence of light chain restriction in labial gland biopsies of patients with SS and provides objective quantitative criteria to identify those patients at greater risk of lymphoma development.