o objetivo desse estudo  descrever os aspectos microscpicos das tsb a fim de contribuir para o seu diagnstico final . foram removidos cirurgicamente 24 espcimes de 19 pacientes ( 15 mulheres e 4 homens ) que possuam tsb . o material foi processado para exame microscpico e corado com hematoxilina - eosina , tricrmico de mallory e cido peridico de schiff ( pas ) . o epitlio do soalho bucal estava normal em 17 casos , hiperplsico em 4 e atrfico em 3 . seis das 24 glndulas sublinguais removidas eram normais microscopicamente , enquanto que as demais apresentaram atrofia acinar com hiperplasia de estruturas ductiformes . fibrose intersticial foi observada em 18 casos sendo acompanhada por infiltrao de tecido adiposo em 15 casos . sugerimos que as tsb em pacientes edntulos e parcialmente edntulos devem ser classificadas como " entidade " nos livros texto . enlargement of the major salivary glands is observed in sjgren 's syndrome , alcoholism , amyloidosis , diabetes , sarcoidosis , gout , myxoedema , lymphomas , obesity , and uremia1,2,3 . other local diseases such as sialolithiasis , sialoadenitis and benign lymphoepithelial lesions3 also cause swelling . non - neoplastic enlargements can be observed in the minor salivary glands , especially in the palate . they have been called adenomatoid hyperplasia of the mucous salivary glands4 . the same type of proliferation occurring in serous acini of the sublingual gland has been denominated adenomatoid serous hyperplasia of the sublingual gland3 . asymptomatic mouth floor enlargements ( mfe ) have been observed in edentulous and partially edentulous patients8,9,10 and may cause difficulties in the fitting of dentures.11,12 these swellings are masses that protrude from the mouth floor , are soft upon palpation , and are covered by a normal appearing mucosa . they are asymptomatic and the patient is unaware of the time of evolution8,9,10 . although some authors consider these enlargements to be normal variations of the mouth floor resulting from bone resorption in the alveolar margin13,14 , campos8 described these swellings for the first time in 1996 as a pathological entity and denoted them " hyperplasia of the sublingual glands " . the microscopic aspects and etiopathogenesis of these enlargements are still not completely understood and they do even not appear as a nosologic entity in current classifications . some patients with mfe , in addition to difficulties in the fitting of dentures , are susceptible to bite trauma and require surgical treatment9,10 . this study aims at describing the microscopic aspects of mfe that contribute to their final diagnosis . twenty - four specimens were obtained from the enlarged mouth floor of 19 patients ranging in age from 48 to 74 years ( mean of 57 years ) between 1985 and 1998 . the patients were referred by the prosthodontist to the department of stomatology , bauru dental school , university of sao paulo , due to difficulties in fitting the mandibular dentures . mfe included swellings that were soft upon palpation , covered by a normal appearing mucosa and asymptomatic . the swellings were spindle - shaped masses whose size and position changed with the extent of opening of the patient 's mouth and tongue movement , and they appeared to be sublingual glands protruding from the mouth floor ( figure 1a ) . analysis of the medical history of patients revealed at least one systemic disease in eight cases : anemia in 1 patient , rheumatism in 1 , liver cirrhosis in 1 , diabetes in 2 , and arterial hypertension in 7 . all eight patients had clinically normal parotid and submandibular glands , which were submitted to examination , palpation and milking . physical aspects of the saliva such as volume , color and fluidity were absolutely normal . surgical intervention consisted of two incisions , one medial and one lateral incision , delimiting an ellipse . the specimens containing mucosa of the mouth floor and most part of the sublingual glands were dissected by divulsion . the surgical site was covered with gauze for 24 h and submitted to healing by second intention to avoid sublingual hematoma and to prevent ranula formation from other minor salivary glands . all patients were treated with antibiotics , analgesics and non - hormonal anti - inflammatory drugs . mouthwash containing 50% h2o2 ( 10 v ) was prescribed for one week to help in the cleaning of the surgical site . in most cases , postoperative control examinations were carried out after 1 , 3 , 7 , 15 and 90 days ( figure 1b ) . after this period , the patients were referred back to the department of prosthodontics for prosthetic rehabilitation . the specimens were fixed in 10% formalin , processed according to routine procedures , and the slides were stained with hematoxylin - eosin , mallory 's trichrome and periodic - acid schiff . the following microscopic aspects were analyzed : 1 ) acinar atrophy , 2 ) hyperplasia of duct - like structures , 3 ) interstitial fibrosis , 4 ) increased adipose tissue , 5 ) decreased lymphoid tissue , 6 ) retention of intraductal mucus , 7 ) overflow of mucus to the stroma , 8) inflammatory infiltrate , 9 ) oncocytosis , 10 ) epithelial thickening of the oral mucosa , and 11 ) submucosal characteristics . acinar atrophy was classified as discrete ( when the number of normal acini exceeded that of atrophic acini ) , moderate ( when the number of normal acini was equal to the number of atrophic acini ) , or intense ( when the number of atrophic acini exceeded that of normal acini ) . adipose tissue was only analyzed regarding its presence or absence in both connective tissue septa and parenchyma , but was not quantified . lymphoid tissue was considered to be normal when aggregated in the periductal or perivascular region , disorganized when undergoing disaggregation , and decreased when the number of mononuclear cells among atrophic acini was smaller than during the disorganization phase upon general observation . of the 19 patients ( 15 males and 4 females ) , 14 were white and 5 were black . mfe were bilateral in 5 patients and unilateral in 14 , with 10 on the right side and 4 on the left . microscopically , the swellings were represented by mucosa and submucosa of the mouth floor and by the sublingual gland . six of the 24 glands removed were considered to be microscopically normal ( figure 2a ) and 18 presented alterations according to the criteria established in the methods section . the frequency of the microscopic findings observed in the altered glands is shown in figure 3 . all 18 altered glands showed acinar atrophy , which was discrete in 2 cases , moderate in 4 and intense in 12 . the number of ducts and/or duct - like structures was found to be increased in all cases of atrophy ( figure 2b ) . interstitial fibrosis was observed in 17 specimens , being discrete in 3 , moderate in 5 and intense in 9 ( figures 2c and 2d ) . infiltration of adipose tissue associated with fibrosis was observed in 15 cases ( figures 2c and 2d ) . retention of intraductal mucus was detected in 17 glands ( figure 2b ) , while none of the specimens showed overflow of mucus to the stroma . a mononuclear inflammatory infiltrate , although discrete , was noted in 16 cases , while polymorphonuclear cells were absent . lymphoid tissue was present in 20 cases , being normal in 4 cases and reduced in 16 ( figures 2e and 2f ) . the epithelium of the mucosa of the mouth floor was normal in 17 , atrophic in 3 , and hyperplastic in 9 specimens . the lamina propria was normal in 15 specimens and showed an inflammatory infiltrate in the other nine . many dentists consider mfe to be a normal variation in this region , a fact also mentioned in some textbooks13,14 . however , these swellings impair denture stability11,12 and are vulnerable to trauma , sometimes requiring surgical treatment9,10 . therefore , knowledge about the microscopic aspects of these enlargements can make an important contribution to the final diagnosis . what would be the etiopathogenesis of mfe if only some partially edentulous and edentulous patients develop them ? if tooth loss would be the only reason , all edentulous patients should show these enlargements . however , our data and those reported by campos8 demonstrate that previous tooth loss is at least one of the criteria for a patient to develop swellings . in the two series mentioned , all patients were edentulous or partially edentulous . according to gershkoff and goldberg14 , protrusion of the sublingual glands beyond the alveolar margin is determined by the level of insertion of the mylohyoid muscle . we agree with this observation since mouth floor mobility and the extent of opening of the mouth exacerbate the mfe . however , they are probably not the only factors since many edentulous patients with severe bone resorption in the alveolar margin do not have mfe . although eight patients of the present sample had a history of systemic diseases , no clinical alterations were observed in any other major salivary gland , especially the parotid glands which are the main targets of systemic involvement in sialosis and sjgren 's syndrome1,15,16 . in addition , no specific complaint such as xerostomia , xerophthalmia , swelling or pain was reported by the patients . furthermore , the microscopic picture of these disorders is also different . in sialosis , acinar cell hypertrophy , this infiltrate can spread throughout the gland , forming germinative centers , followed by acinar atrophy , fibrosis , hyalinization and fat infiltration , with replacement of the parenchyma16 . this final manifestation of sjogren 's syndrome may resemble the microscopic picture of mfe seen in figures 2c , 2d , and 2e . the hypothesis regarding a traumatic etiology of mfe is very strong , since in the present study all swellings were observed in edentulous ( 6 cases ) and partially edentulous patients ( 13 cases ) . draining of food during mastication using dentures or the teeth adjacent to edentulous areas could damage the mouth floor , which is not a masticatory mucosa . however , since most edentulous patients do not present mfe , factors other than trauma , which are still unknown , might also be involved . this fact is supported by the present observation that 17 of 24 specimens showed a normal epithelium of the mouth floor , while a hyperplastic epithelium was observed in only 4 cases . the combination of masticatory trauma and the insertion level of the mylohyoid muscle might have been one of the possible causes . the microscopic aspects of mucocele in minor salivary glands17 or of the parotid gland after ligation of the main duct18 closely resemble the picture of acinar atrophy observed here . souza et al18 , studying rats submitted to parotid duct ligation and sacrificed after different periods of time , observed acinar atrophy , ductal proliferation accompanied by hyperplasia and dilatation , and interstitial fibrosis , similar to the microscopic findings observed here ( figures 2b , 2c and 2d ) . moreover , oliveira , et al.17 also demonstrated the presence of intraductal substance , as observed here in 17 specimens ( figure 2b ) . in contrast to the study of souza , et al.18 in which glandular volume was unaltered , in the present study the mouth floor was always found to be enlarged ( figure 1a ) . normally , obstruction of the excretory duct of a gland leads to enlargement of the organ , which becomes firm upon palpation . lymphocytes , the only inflammatory cells observed upon microscopic examination , decrease while acinar atrophy increase ( figures 2e and 2f ) . probably , these cells abandon the gland as it loses its function , thus excluding inflammation as a possible cause of the volume increase observed . salivary glands suffer age - related changes such as acinar atrophy , fibrosis , fat infiltration , ductal proliferation and oncocytosis1925 . azevedo , et al.26 analyzed age - and - gender related microscopic changes in 186 sublingual glands obtained from human cadavers . the study showed that the aging process starts with acinar atrophy , followed by the presence of duct - like structures and ends with replacement of the parenchyma by fibrous and/or adipose tissue , without differences between man and woman . the mean age of patients in the present study was 57 years , a fact supporting the role of aging as an additional etiologic factor , together with the functional alterations resulting from previous tooth loss . nevertheless , moreira27 showed a decrease in sublingual gland volume with age of 33.73% in a histomorphometric study of human cadavers . these results discard the aging process hypothesis as one of the etiopathogenesis of mfe . on the other hand , we can speculate that mfe represent an exacerbated elasticity of the mucosa of the mouth floor in some individuals . it would be related to the free tongue movements related to tooth loss and a high insertion of the mylohioide muscle . hyperplasia of the sublingual glands8 also seems to be inappropriate because this organ is almost always microscopically atrophic . one may call this condition a kind of " atrophic sialadenosis " ; however , in the present study six glands showed normal microscopic aspects ( figure . the same aspects were observed in a study by campos8 where five specimens were microscopically normal . a semi - serial study might be useful to demonstrate the onset of atrophy in the organ , although cases showing normal microscopic aspects are known to even further impair hypotheses about the etiopathogenesis of mfe . new investigations will be necessary to clarify the etiology of mfe that is probably multifactorial . nevertheless , sufficient information is available indicating that mfe can at least be classified as an " entity " in the text books of oral medicine and oral pathology .
mouth floor enlargements ( mfe ) are observed in edentulous and partially edentulous patients , impairing denture fitting , and have recently been described in the literature as hyperplasias of the sublingual glands.objective:this study aims at describing the microscopic aspects of mfe that contribute to their final diagnosis.methods:twenty-four specimens were surgically removed from the enlarged mouth floor of 19 patients ( 15 females and 4 males ) . 
 patient age ranged from 48 to 74 years , with a mean of 57 years . 
 the main surgical indication was to permit or improve the fitting of dentures . 
 six patients were completely edentulous and 13 were partially edentulous . 
 the material was processed for microscopic examination and stained with hematoxylin - eosin , mallory 's trichrome and periodic - acid schiff ( pas).results and conclusions : the epithelium of the mouth floor was normal in 17 cases , hyperplastic in 4 and atrophic in 3 . 
 six of the 24 sublingual glands removed were microscopically normal , while the other specimens presented acinar atrophy with hyperplasia of duct - like structures . 
 interstitial fibrosis was observed in 18 cases and was accompanied by adipose tissue infiltration in 15 . 
 decreased lymphoid tissue was observed in 16 samples and oncocytosis was present in 5 cases . 
 we suggest that mfe in edentulous or partially edentulous patients should be considered as an entity for the text books .