Sjogren's syndrome: clinical spectrum and current diagnostic controversies

Salivary gland developmental mechanics

The salivary gland undergoes branching morphogenesis to elaborate into a tree-like structure with numerous saliva-secreting acinar units, all joined by a hierarchical ductal system. The expansive epithelial surface generated by branching morphogenesis serves as the structural basis for the efficient production and delivery of saliva. Here, we elucidate the process of salivary gland morphogenesis, emphasizing the role of mechanics. Structurally, the developing salivary gland is characterized by a stratified epithelium tightly encased by the basement membrane, which is in turn surrounded by a mesenchyme consisting of a dense network of interstitial matrix and mesenchymal cells. Diverse cell types and extracellular matrices bestow this developing organ with organized, yet spatially varied mechanical properties. For instance, the surface epithelial sheet of the bud is highly fluidic due to its high cell motility and weak cell-cell adhesion, rendering it highly pliable. In contrast, the inner core of the bud is more rigid, characterized by reduced cell motility and strong cell-cell adhesion, which likely provide structural support for the tissue. The interactions between the surface epithelial sheet and the inner core give rise to budding morphogenesis. Furthermore, the basement membrane and the mesenchyme offer mechanical constraints that could play a pivotal role in determining the higher-order architecture of a fully mature salivary gland.

Oral Rehabilitation and Management for Secondary Sjögren’s Syndrome in a Child

The aim of this paper is to describe a rare case report of a pediatric patient with secondary Sjögren's syndrome (SSS). A 12-year-old female child was referred to the Pediatric Dentistry Clinic with the chief complaint of tooth pain, dry mouth, and tooth sensibility. The patient was submitted to orthodontic treatment prior to syndrome diagnosis. The clinical treatment consisted of the interruption of orthodontic treatment and restoring the oral condition with dental treatment and the use of artificial saliva in an innovative apparatus. Dental therapy involved the control of dental caries, periodontal disease, and opportunistic fungal infections and the use of fluoride-rich solutions. The present clinical case describes clinical and laboratory aspects of SSS in pediatric patients. The management of the oral findings promoted an improvement in the oral health status and quality of life of the child.

Saliva as a diagnostic tool for oral and systemic diseases

Early disease detection is not only vital to reduce disease severity and prevent complications, but also critical to increase success rate of therapy. Saliva has been studied extensively as a potential diagnostic tool over the last decade due to its ease and non-invasive accessibility along with its abundance of biomarkers, such as genetic material and proteins. This review will update the clinician on recent advances in salivary biomarkers to diagnose autoimmune diseases (Sjogren's syndrome, cystic fibrosis), cardiovascular diseases, diabetes, HIV, oral cancer, caries and periodontal diseases. Considering their accuracy, efficacy, ease of use and cost effectiveness, salivary diagnostic tests will be available in dental offices. It is expected that the advent of sensitive and specific salivary diagnostic tools and the establishment of defined guidelines and results following rigorous testing will allow salivary diagnostics to be used as chair-side tests for several oral and systemic diseases in the near future.

Clinical and laboratorial profile and histological features on minor salivary glands from patients under investigation for Sjögren's syndrome

Diagnosis of Sjögren’s syndrome (SS) is complex and the usefulness of labial minor salivary glands biopsy in this process remains controversial. Objectives: to evaluate the clinical and laboratorial profile and histological features on labial minor salivary glands from patients under investigation of SS. Study Design: clinical charts from 38 patients under suspicion of SS and submitted to labial minor salivary glands biopsies were reviewed. Clinical and laboratorial data were retrieved from the clinical files and the HE-stained histological slides were reviewed under light microscopy. Results: mean age of the patients was 56.5 years and 97% were females; histological analysis showed that 42% of the cases showed ductal dilatation, lymphocytic foci were found in 52.6% and, from this group, 80% of the cases presented a foci/lobules ratio above 0.8. Acinar/ductal ratio was considered diminished in 39.5% of the samples. Thirty six (95%) and 32 (84%) patients, respectively, complained about xerostomia and xerophthalmia. A study of the time interval of the symptoms that led to SS investigation showed a mean of 116 months. Moreover, sixty-six percent of the patients had already been submitted to immunosuppressive therapy prior to the labial minor salivary gland biopsy. Age of the patients, scintigraphic alterations on salivary function, antinuclear factor (ANF), anti-Ro and anti-La did not show statistical significant association with the histological features. Lobules/foci ratio above 0.8 was the only histological parameter statistically associated with Sjögren’s syndrome diagnosis (p<0.0001). Conclusions: in the studied sample, lymphocytic foci on salivary glands were the only histological parameter associated to the diagnosis of SS. Early indication of labial minor salivary gland biopsy to patients under investigation of SS could limit the effects of immunosuppressive therapy on the histological features associated with the evolution of salivary gland involvement in SS.

Key words:Sjögren syndrome, minor salivary glands, biopsy, lymphocytic foci.

Discovery of putative salivary biomarkers for Sjögren's syndrome using high resolution mass spectrometry and bioinformatics

The purpose of the current study was to determine if saliva contains biomarkers that can be used as diagnostic tools for Sjögren's syndrome (SjS). Twenty seven SjS patients and 27 age-matched healthy controls were recruited for these studies. Unstimulated glandular saliva was collected from the Wharton's duct using a suction device. Two µl of salvia were processed for mass spectrometry analyses on a prOTOF 2000 matrix-assisted laser desorption/ionization orthogonal time of flight (MALDI O-TOF) mass spectrometer. Raw data were analyzed using bioinformatic tools to identify biomarkers. MALDI O-TOF MS analyses of saliva samples were highly reproducible and the mass spectra generated were very rich in peptides and peptide fragments in the 750-7,500 Da range. Data analysis using bioinformatic tools resulted in several classification models being built and several biomarkers identified. One model based on 7 putative biomarkers yielded a sensitivity of 97.5%, specificity of 97.8% and an accuracy of 97.6%. One biomarker was present only in SjS samples and was identified as a proteolytic peptide originating from human basic salivary proline-rich protein 3 precursor. We conclude that salivary biomarkers detected by high-resolution mass spectrometry coupled with powerful bioinformatic tools offer the potential to serve as diagnostic/prognostic tools for SjS.

The role of adipokines in connective tissue diseases

Objective

To discuss the relationship between adipokines and connective tissue diseases, by putting special emphasis on the potential role of leptin, adiponectin, resistin, and other adipose tissue products in the pathogenesis of rheumatoid arthritis and systemic lupus erythematosus and on possible application of adipokine-targeted therapy in the treatment of these disorders with emphasis on the recent findings.

Methods

PubMed literature search complemented by review of bibliographies listed in identified articles.

Results

Most of the data presented by different research groups showed changed levels of leptin, adiponectin, and resistin and occasionally also other adpokines in rheumatoid arthritis and systemic lupus erythematosus. The relationship between the remaining connective tissue diseases and adipokines is less documented.

Conclusions

Plasma levels of adipokines might tell us too little about their role in connective tissue disorders, whereas adipokine effects on synovial tissues might differ from their known metabolic or cardiovascular effects, which implies that some re-appraisal of adipokines role may need to take place. It still remains obscure whether the observed disturbances in various adipokine systems in subjects with connective tissue diseases contribute to their development or only reflect the presence or activity of inflammatory process, which itself is induced by other pro-inflammatory factors.

Multiple OralCandidaInfections in Patients with Sjögren’s Syndrome — Prevalence and Clinical and Drug Susceptibility Profiles

Objective.

To determine the prevalence of oral candidiasis and multiple oralCandidainfections in patients with primary Sjögren’s syndrome (SS), and the clinical and drug susceptibility profile.

Methods.

Thirty patients with primary SS were enrolled in our study. The diagnosis of oral candidiasis was based on the clinical manifestation, and confirmed by a concentrated rinse culture.Candidaspp. assessment was accomplished using standard methods: Sabouraud dextrose agar with 50 mg/l chloramphenicol and CHROMagar were used for the rapid screening of clinical species, followed by the API 20C system for further species identification.In vitroantifungal drug susceptibility ofCandidaisolates was determined by the minimal inhibitory concentrations.

Results.

In our study, 87% (26/30) of subjects had oral candidiasis, in which 42% (11/26) had multipleCandidaspp. infection. AlthoughC. albicansremains the predominant isolate, other rare species such asC. tropicalis,C. glabrata,C. parapsilosis, andC. kruseiwere present, alone or in combination. Chronic atrophic candidiasis is the most common clinical type of oral candidiasis in patients with SS. The susceptibilities of the 44Candidaisolates to 7 antifungal agents varied dramatically. The resistance to azoles was remarkable, and the phenomenon of cross-resistance between itraconazole and fluconazole was observed.

Conclusion.

Patients with primary SS carry a high risk of oral candidiasis and a high frequency of multipleCandidainfections. The azole resistance patterns ofCandidaspp. support the necessity for drug susceptibility testing as a routine procedure for patients with oralCandidainfections.

[Etiologic treatment of sicca syndrome. What can the rheumatologist offer?]

No effective treatment has been documented for the glandular primary Sjögren syndrome (PSS) despite the development of oral and biologic agents that have significant activity against other autoimmune disorders. Some disease-modifying agents have been empirically evaluated for the treatment of PSS. Targeting B cells also seems very promising in SSP because of the B-cell hyperactivity recognized in this desease. This article reviews existing data on the use of disease-modifying therapy for glandular of SSP. To date, published studies and trials of oral DMARDs for the treatment of SSP have shown disappointing results. B-cell modulation is clearly a promising therapy for PSS. Many challenges in trial design and execution are evident from the studies reviewed.

Opening the flood gates: interferon-alpha treatment for Sjögren's syndrome

Interferon (IFN)-alpha is the main IFN produced in response to viral infection. Low levels of IFNalpha can be detected in nasal secretions after exposure to viruses in vivo. Radioimmunoassay has shown that endogenous IFNalpha is low in children, reaches a peak in young adults, and gradually declines with aging. Importantly, this endogenous IFNalpha is significantly decreased in patients with Sjögren's syndrome (SS). IFNalpha has been tested as a therapeutic agent in patients with SS. Intramuscular human leucocyte IFNalpha increases saliva production significantly in patients with SS. Improvements have been noted in lacrimal function and in dryness symptoms. Since IFNalpha infrequently induces autoimmune phenomena and high dose IFNalpha treatment sometimes has a serious adverse event profile, treatment focus has shifted to use of low dose orally-administered IFNalpha. In a single-masked controlled trial, 60 patients with SS randomly received natural human IFNalpha 150IU 3 times a day in an oral lozenge formulation or sucralfate as control for 6 months. At study end, 15 (50%) of the 30 IFNalpha-treated patients had saliva production increases at least 100% above baseline. IFNalpha treatment was well tolerated and no patients withdrew. Labial minor salivary gland biopsies indicated significant decreases in lymphocytic infiltration accompanied by a significant increase in intact salivary gland tissue after 6 months of treatment. In another 12-week double-masked, randomised, placebo-controlled trial, stimulated saliva production in patients with SS receiving IFNalpha lozenges 150IU 3 times daily was significantly increased. This dosage was also suggestive of benefit for 5 of 7 subjective measures of oral and ocular comfort. The tolerability profile of these low dose oral IFNalpha lozenges is excellent; no serious adverse events have been recorded. Adverse effects were generally mild and there were no clinically significant changes in laboratory or clinical safety measures. Low oral doses of natural human IFNalpha thus appear to improve secretory function and relieve dryness in patients with SS without causing significant adverse events. Endogenous or orally administered IFNalpha may activate oropharyngeal lymphoid and epithelial cells and induce production of potent soluble factors which could mediate immunological reactivity. It has been suggested that IFNalpha/beta potentiates clonal expansion and survival of CD8 T cells. Stimulating effects have also been demonstrated on natural killer cell activity, which has been shown to be depressed in patients with SS. It is likely that some combination of these immunological effects results in anti-inflammatory activity and ameliorates signs and symptoms of SS.

Saliva as a diagnostic fluid

The use of saliva as a diagnostic fluid for various human ailments is gaining popularity as it offers distinct advantages over serum. These include the non-invasive nature of saliva collection compared with phlebotomy, simplicity of collection even for individuals with a modest training and the cost-effective applicability for screening large populations. Whole saliva is most frequently used for diagnosis of systemic diseases since it is readily collected and contains serum constituents while gland-specific saliva is useful for investigating pathology of major salivary glands. Broadly, saliva analysis is currently used for the diagnosis of infectious and malignant diseases, hereditary disorders, autoimmune diseases, and endocrine disorders, as well as for the assessment of therapeutic drug levels, particularly in monitoring drug abuse. This review addresses the current status of salivary diagnostics and their future potential.

Periodontitis, caries and salivary factors in Sjögren's syndrome patients compared to sex- and age-matched controls

The aims of this investigation were: (i) to study a group of dry mouth Sjögren's syndrome (SS) patients comprising individuals with pathological and non-pathological amounts of rest saliva and (ii) to compare these two categories of SS patients with a sex- and age-matched control group with respect to their periodontal and dental status. Thirty-three dry mouth patients and 33 sex- and age-matched patients, referred to the same private dental clinic in southern Norway, were examined for rest and stimulated saliva, as well as their dental and periodontal status. All patients were referred to the local hospital for blood and urine examinations. The dry mouth SS patients were all of the secondary type. Volumes of rest and stimulated saliva were significantly lower in the low saliva SS group compared with the high saliva SS group; the values for immunoglobulin G (IgG) and IgA were similarly lower for the low saliva group, but not for IgM which was significantly higher. The two SS subgroups and their controls were compared for the volume of rest and stimulated saliva, which showed a statistically significant lower volumes for the low saliva SS group compared with the control group. None of the subgroups and their controls differed concerning filled or missing teeth, but the total SS group revealed significantly higher number of missing teeth. The periodontal and dental status did not show any statistically significant differences except for a few scattered higher periodontal level losses of attachment in the SS subgroups. The blood and urine analyses showed statistically significant higher values for sedimentation rate, white blood cell count and haemoglobin in the SS low saliva group compared with the control group while anti-streptolysin was lower. In the high saliva SS group only sedimentation rate and white cell count were higher compared with the control. The conclusions is SS patients do not have an increased risk for developing periodontitis.

A third study on the use of orally administered anhydrous crystalline maltose for relief of dry mouth in primary Sjögren's syndrome

OBJECTIVES

To examine the safety and efficacy of anhydrous crystalline maltose for treatment of dry mouth and other symptoms of dryness in patients with primary Sjögren's syndrome.

DESIGN

Anhydrous crystalline maltose was delivered orally as a 200-mg lozenge given three times daily over a 24-week period to a total of 100 subjects. All participants had prominent complaints of persistent dry mouth associated with primary Sjögren's syndrome. Patients were examined at baseline and every 6 weeks of treatment.

SETTINGS

Patients were seen in outpatient clinics at a total of 27 sites within the United States.

OUTCOME MEASURES

Unstimulated whole saliva output, a measure of basal salivary gland function, was determined at each visit. Symptoms associated with oral and ocular dryness were assessed at the same time with the use of 100-mm visual analogue scales. Safety was assessed by physical examination and laboratory studies.

RESULTS

During this clinical trial, a majority of evaluable subjects (39/76) demonstrated an increase in unstimulated whole saliva output, and the treatment exhibited an excellent safety profile. The anhydrous crystalline maltose treatment led to significant improvement in several subjective measures of oral and ocular comfort.

CONCLUSIONS

In this study, anhydrous crystalline maltose lozenges administered three times daily for 24 weeks improved salivary output and decreased complaints of dry mouth and eyes in patients with primary Sjögren's syndrome. Side-effects were minimal, and treatment was without significant adverse events. These results are similar to the benefits observed in two prior studies reported by the authors. This safe and simple intervention appears to provide clinical benefit to primary Sjögren's syndrome patients with distressing dry mouth symptoms.

Saliva as a diagnostic fluid

In the last 10 years, the use of saliva as a diagnostic fluid has become somewhat of a translational research success story. Technologies are now available enabling saliva to be used to diagnose disease and predict disease progression. This review describes some important recent advances in salivary diagnostics and barriers to application and advancement. This review will also stimulate future research activity.

The physiology, medical management and oral implications of menopause

BACKGROUND

Approximately 36 million women in the United States are in the postmenopausal phase of life. The vast majority of these women experienced spontaneous cessation of menses between the ages of 47 and 55 years when the production of estrogen decreased because of an inadequate number of functioning follicles within their ovaries. Fewer women entered menopause after surgical removal of both ovaries. This procedure usually is performed prophylactically to prevent ovarian cancer in conjunction with a hysterectomy, which is required to treat abnormal bleeding, endometriosis or pelvic inflammatory disease. The physiological changes associated with spontaneous or surgical menopause cause some women to experience uncomfortable symptoms such as hot flashes, night sweats and vaginal dryness. In addition, estrogen deprivation arising from menopause in association with age-related factors disproportionately increases the risk of developing cardiovascular disease (that is, myocardial infarct, stroke), osteoporosis, Alzheimer's disease and oral disease. Hormone replacement therapy, or HRT (estrogen or estrogen and progestin), often is prescribed on a short-term basis to alleviate the uncomfortable symptoms associated with estrogen deficiency and on a long-term basis to prevent some of the chronic illnesses common to postmenopausal women.

CONCLUSIONS

Dentists who treat women entering menopause need to consider the stressful phase of life their patients are experiencing. Clinical findings of postmenopausal problems on dental examination may include a paucity of saliva, increased dental caries, dysesthesia, taste alterations, atrophic gingivitis, periodontitis and osteoporotic jaws unsuitable for conventional prosthetic devices or dental implants. Panoramic dental radiographs may reveal calcified carotid artery atheromas.

CLINICAL IMPLICATIONS

Dentists have an opportunity to refer women who are not under the care of a gynecologist for an evaluation to determine the appropriateness of HRT for its systemic and oral health benefits.

Primary Sjögren's syndrome: oral aspects on pathogenesis, diagnostic criteria, clinical features and approaches for therapy

Primary Sjögren's syndrome (pSS) is a chronic inflammatory systemic autoimmune disease affecting the exocrine glands and predominantly the salivary and lacrimal glands. The impaired gland function is assumed to be a result of progressive lymphocyte-mediated destruction of the exocrine gland tissue leading to the cardinal manifestations, hyposalivation and keratoconjunctivitis sicca (KCS), as well as devastating symptoms of oral and ocular dryness. Although primarily characterised as an exocrine dysfunction, non-exocrine organs may also be affected. The onset and course of pSS is usually insidious but may develop into a disabling disease, which profoundly affects the patient's general well being and quality of life. Moreover, pSS may even evolve into a lymphoid malignancy. The aetiology of pSS remains unknown but the pathogenesis of exocrine cell damage is apparently multi-factorial, including immunological, genetic, hormonal and viral components. Recent research also includes neurogenic aspects of exocrine gland dysfunction, including the interference of immune mediators with glandular response to neurotransmitters released from nerve fibres. pSS usually affects middle-aged women and the female:male ratio is 9:1. The prevalence varies from 0.29-4.8%, depending on the population sampled and the diagnostic criteria used. At present, there are no specific diagnostic tests for pSS and no universally accepted diagnostic criteria. The current therapy is primarily symptomatic. This review focuses on the current oral clinical, diagnostic, pathogenic and therapeutic aspects of pSS.

Use of orally administered anhydrous crystalline maltose for relief of dry mouth

OBJECTIVES

To examine the safety and efficacy of anhydrous crystalline maltose (ACM) for treatment of dry mouth.

DESIGN

ACM was delivered orally as a 200-mg lozenge given three times daily over a 12-week (study Alpha) or 24-week (study Omega) period to a total of 22 and 97 subjects, respectively. All participants had prominent complaints of persistent dry mouth associated with primary Sjögren's syndrome. Patients were examined every 4 weeks in study Alpha and every 6 weeks in study Omega.

SETTINGS

Patients were seen in outpatient clinics at a total of 33 sites within the United States.

OUTCOME MEASURES

Unstimulated whole saliva output, a measure of basal salivary gland function, was determined at each visit. Symptoms associated with oral and ocular dryness were assessed at the same time with the use of 100-mm visual analog scales. Safety was assessed by physical examination and laboratory studies.

RESULTS

During these clinical trials, a majority of subjects demonstrated an increase in unstimulated whole saliva output and the treatment exhibited an excellent safety profile. The ACM treatment in study Omega led to significant improvement in several subjective measures of oral and ocular comfort.

CONCLUSIONS

In these two studies, ACM lozenges administered three times daily for 12 or 24 weeks improved salivary output and decreased complaints of dry mouth and eyes. Side effects were minimal, and treatment was without significant adverse events. This safe and simple intervention may provide clinical benefit to individuals with distressing dry mouth symptoms.

Diagnostic value of sialography with both the conventional and digital subtraction techniques in children with primary and secondary Sjögren's syndrome

OBJECTIVE

The application of anamnestic data on siccative symptoms required for classifying adult Sjögren's syndrome is limited in childhood. Instrumental test procedures are therefore necessary for objectively recording the oral and ophthalmologic manifestations of the disease. The aim of this study was to clarify the sialographic changes that occur in Sjögren's syndrome in children.

STUDY DESIGN

A total of 23 sialograms were obtained with both conventional and digital subtraction techniques in 21 children with primary (10 girls and 1 boy) or secondary Sjögren's syndrome (10 girls). The films were assessed by 3 physicians and submitted for a consensus analysis if necessary.

RESULTS

The pathologic features observed in the children varied from a slightly narrowed ductal system to multiple peripheral ductal ectasias and completely destroyed parenchyma. Sialographic examinations demonstrate that, with progressing disease, regression of acinar dilatations and rarification of the ductal system occur.

CONCLUSION

The results show that the spectrum of sialographically recordable lesions in Sjögren's syndrome in children is greater than is described thus far in the literature.

Treatment of primary Sjögren's syndrome with low-dose natural human interferon-alpha administered by the oral mucosal route: a phase II clinical trial. IFN Protocol Study Group

The purpose of this investigation was to examine the safety and efficacy of four dosages of natural human interferon-alpha (nHuIFN-alpha) delivered over a 12-week period orally in lozenges (150 IU and 450 IU, once [QD] or three times [TID] daily) compared to placebo in subjects with primary Sjögren's syndrome. This randomized, double-blinded clinical trial demonstrated that nHuIFN-alpha at a dose of 150 IU administered TID by oral lozenge significantly improved stimulated whole saliva output compared to placebo after 12 weeks of treatment. The 150 IU TID dose also was suggestive of benefit for 5 of 7 subjective measures of oral and ocular comfort. IFN lozenges demonstrated a good safety profile, with no serious adverse events found in any treatment group. There were no significant differences between the placebo and the four doses of IFN for adverse events by total number, organ system, severity, dropouts, and number judged to be related to treatment. In conclusion, these results demonstrated that the use of 150 IU IFN lozenges TID for 12 weeks in subjects with primary Sjögren's syndrome improved salivary output and decreased complaints of xerostomia without causing significant adverse medical events.

Rheumatologic disorders in women

This article reviews common rheumatic diseases that most frequently occur in women including fibromyalgia, rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus and the antiphospholipid antibody syndrome. Many of these women are of child bearing potential and special considerations concerning pregnancy often arise. Rheumatic conditions that frequently affect older women such as osteoarthritis and polymyalgia rheumatica are discussed as well. Osteoporosis, which has emerged as a significant women's health issue, is also reviewed.

Differentiation of dry mouth etiology

Dry mouth is a common complaint. While it is often considered to be synonymous with the diagnosis of salivary gland disease, this is not the case. There are many causes of the symptomatic complaint of oral dryness, both salivary and non-salivary. This paper will review the causes of "dry mouth" and the means of establishing the underlying diagnosis.

Current concepts of autoimmune exocrinopathy: immunologic mechanisms in the salivary pathology of Sjögren's syndrome

Sjögren's syndrome is a systemic autoimmune disorder characterized by symptoms of oral and ocular dryness and a chronic, progressive loss of salivary and lacrimal function. The exocrine involvement is the result of a focal, peri-ductal mononuclear cell infiltrate and the subsequent loss of secretory epithelial cells. The mechanisms of this autoimmune exocrinopathy are not understood fully. Many recent investigations have described alterations in a number of immune mediators within the salivary glands. These studies provide new insights into the immune regulation of normal salivary gland functions and the mechanisms of gland damage in Sjögren's syndrome.

Is sialography effective in diagnosing the salivary component of Sjögren's syndrome?

Parotid sialography has been used for many years as a means of assessing salivary glands in Sjögren's syndrome (SS), and it is occasionally used as a diagnostic criterion for the salivary component of SS. To assess its diagnostic effectiveness, we reviewed studies in which sialography was applied to patients with SS and control subjects for the purpose of estimating its diagnostic sensitivity and specificity or comparing it with other means of assessing salivary glands. Sialography appears to be diagnostically less sensitive but more specific than salivary flow rate measurement and more sensitive but less specific than labial salivary gland (LSG) biopsy. Such calculations are based on the diagnosis of SS established in each study, but the various studies used widely different criteria to establish that diagnosis. Therefore, these calculations are not based on a consistent standard, and comparison between the calculations may be misleading, which underscores the need to develop internationally accepted diagnostic criteria for SS. Studies conducted so far have not shown that parotid sialography is either a sensitive indicator of the salivary component of SS or more closely associated than LSG biopsy with keratoconjunctivitis sicca, the only other component of primary SS with which ultimately to assess diagnostic specificity.