CLlNlCOSTATlSTlCAL STUDY OF LOWER LIP MUCOCELES Tatsuya Yamasoba, MD, Nirou Tayama, MD, Minoru Syoji, MD, and Masahiro Fukuta, MD
We reviewed 70 patients with lower lip mucoceles for patient characteristics, clinical features, and histopathologic findings. These cases represented approximately 75% of oral mucoceles seen in the Department of Otolaryngology, Takeda General Hospital, between February 1985 and July 1988. Patients were divided almost equally between males and females, with ages ranging from 2 to 63 years, with the highest incidence of lesions occurring in the second decade. Duration of the lesions varied greatly from a few days to 3 years, with no correlation to size. The most commonly affected site was opposite the upper lateral incisor, with the incidence divided almost equally between right and left side. Of 70 biopsies, 68 were mucous extravasation cysts and 2 were mucous retention cysts. Surgical excision was the treatment of choice, with recurrence of the lesion in only 2 cases. HEAD 81 NECK 12:316-320, 1990
Mucoceles are common lesions of the oral mucous membrane involving minor salivary gland tissue. The lower lip is the site most frequently affected. In the past, oral mucoceles were thought to
From the Department of Otolaryngology (Drs. Yarnasoba. Tayama. and Syoli), Faculty of Medicine. Universlty of Tokyo, Tokyo, Japan, and Department of Otolaryngology (Dr Fukuta), Takeda General Hospital. Fukushima, Japan. Acknowledgment. We thank Professor Y Nornura for his advice and the operating theatre staff at Takeda General Hospital for helping with the project. Address reprints requests to Dr Yamasoba at the Department of Otolaryngology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunyo-ku. Tokyo 113, Japan. Accepted for publicallon November 6, 1989
CCC 0148-6403/90/040316-05 $04 00 0 1990 John Wiley & Sons, Inc.
316
Lower Lip Mucoceles
arise from obstruction of an excretory duct, which caused back pressure of mucus and the formation of an epithelial-lined cyst. It is now, however, generally accepted that most mucoceles are caused by trauma-injury or severing of an excretory duct and subsequent escape of mucus into the adjacent tissue. Histopathologically, there are two types of mucoceles: mucous extravasation cysts and mucous retention cysts. The present series of 70 patients is reported for comparison with previous studies in terms of patient age and sex, site of lesion, and histologic features.
MATERIALS AND METHODS
We studied 70 patients with lower lip mucoceles, including 1 patient with 2 lesions, who were treated in the Department of Otolaryngology, Takeda General Hospital, between February 1985 and July 1988. Patient age and sex, site of lesion, time elapsed after onset, clinical description, and histopathologic findings were recorded for all cases. All lesions were removed surgically except for one, which ruptured due to lip-biting and healed on its own. Enucleation was performed for 20 lesions and local excision together with surrounding tissue for 50 lesions. The enucleation technique was used for the larger and deeper lesions, which were not close t o the mucous membrane. After enucleation of the lesion, the minor salivary glands exposed to the surgical area were reHEAD & NECK
July/August 1990
moved. Smaller lesions, and those located just beneath the mucous membrane, were locally excised by making a spindle-shaped incision extending laterally the length of the diameter of the mucocele on both sides. RESULTS
During the 3.5-year period of this study, the total number of oral mucoceles encountered was 92. The percentage of lower lip mucoceles was 76%; the remainder were located in the oral cavity. Of the 70 patients with lower lip mucoceles, 32 were male and 38 female. The youngest patient was 2 years old, and the oldest was 63. The highest incidence occurred in the second decade: 70% of the lower lip mucoceles occurred in patients less than 20 years of age. The duration of lower lip mucoceles varied greatly, from a few days to 3 years. In 8 cases, the duration of the lesion was not stated. Of the 62 cases, in which the duration was recorded, 47 lesions had been present for less than 3 months. No correlation between duration and the size of the mucocele was found. The lesions were commonly painless, freely movable, smooth, soft, and fluctuant. In some cases, the surface was irregular and coated due to several ruptures caused by lip-biting or puncture. The color was dependent on the depth at which the mucus accumulated in the tissue. Superficial lesions usually showed a translucent blue protrusion. The mucosal surface of a deep lesion showed a n almost normal appearance. The size varied from a few millimeters to 25 mm; in 53 lesions, the diameter was less than 10 mm. With regard to the location of the lesion, 50 mucoceles occurred at the area where the upper lateral incisor impinged against the lower lip. The area opposite the canine was affected in 12 cases. Three lesions were found at midline, and the incidence at the side was about the same (Table 1). The lesions were all surgically removed except for that in 1 patient, whose mucocele was ruptured by lip-biting. However, the ruptured lesion healed itself, and no recurrence was found during the following 2 years. Of the surgically removed ones, only 2 cases which were treated by enucleation recurred, and in these 2 cases the lesions were locally excised and healed without recurrence for 2 years. In none of the operated cases did any deformity of the lip occur. Lower Lip Mucoceles
Table 1. Site of lower lip mucoceles. No. of cases
Site Right: opposite to upper canine Lateral incisor Central incisor Left: opposite to upper canine Lateral incisor Central incisor Midline
6
27 3 6 23 3 3
nistology. The specimens seldom presented the characteristic histologic picture of a true cyst lined with an epithelium. Only 2 of 70 biopsies revealed an epithelial lining (Figure 1).None of the remaining 68 cysts had epithelial linings, although the ductal epithelium was adjacent to the connective tissue capsule in 3 cases. The walls of these specimens were usually composed of granulation or fibrous tissue or a mixture of the two. The cyst area of the mucocele usually contained an eosinophilic homogeneous mucoid material and scattered inflammatory cells with a predominance of histocytes (Figure 2). In some cases, a discrete, well-defined cystic structure was lacking and a scattered area of mucus in the surrounding connective tissue was found. In most instances, the lesions were surrounded by salivary gland tissue, which showed varying degrees of inflammation and ductal dilatation. Salivary gland tissue was always located in the submucosal layer, and the mucocele was adjacent to it. Superficial mucoceles close to the mucous membrane were located between the mucous membrane and salivary gland tissue, as shown in Figure 1A. Deeper cysts were situated below salivary gland tissue, as shown in Figure 2A. No correlation could be shown between the duration of the lesion and the changes in the salivary gland tissue. DISCUSSION
Bouquot et al.' studied the epidemiology of benign oral masses in 23,616 persons over 35 years of age and stated that the prevalence of all oral mucoceles was 2.5 lesions/1,000 population. The lower lip is the most frequently encountered site (Table 2); the remainder occur in the cheek, palate, floor of the mouth, tongue, and retromolar fossa. The upper lip is rarely affected. Mucoceles occur most often in children and young adults. Histopathologically, there are 2 types of mucoceles: mucous extravasation cysts HEAD 8, NECK
July/August 1990
317
A
FIGURE 1. (A) Low-power view of a mucous retention cyst with columnar epithelium lining. The superficial cyst is located between the mucous membrane and minor salivary gland tissue. Hematoxylin & eosin, x 15, original magnification. (B) High-power view of a mucous retention cyst. Stratified columnar epithelium is found. Hematoxylin 8 eosin, x250, original magnification.
Table 2. Percentage of lip mucoceles. Lower lip Author Bhaskar et a1.‘ M0l1er3 Standish and Shafer4 Chaudhry et al.5 Robinson and Hjmting-Hansen‘ Cohen’ Sela and Ulmansky’ Cataldo and Mosadomig Harrison” Ishida” Seiferi et a!.’’ Saza et ai.15 Bouquot et a1.l Yamasoba et al. (present study)
318
Lower Lip Mucoceles
Year
No. of oral mucoceles
No.
(1956) (1958) (1959) (1960) (1964) (1965) (1969) (1970) (1975) (1980) (1981) (1982) (1986) (1989)
19 44 97 66 125 82 29 594 55 425 273 385 59 92
11 31 43 45 64 52 21 348 33 336 197 208 33 70
%
Upper lip No.
HEAD & NECK
%
JulylAugust 1990
A
B
FIGURE 2. (A) Low-power view of a mucous extravasation cyst with a wall composed of fibrous tissue. The deep cyst is located below minor salivary gland tissue. Hematoxylin & eosin, x 15, original magnification. (6) High-power view of a mucous extravasation cyst. Note the lack of epithelium. Hematoxylin & eosin, x250, original magnification.
and mucous retention cysts. The latter occur most often in older and account for a small percentage of mucoceles. The highest incidence of the lesion occurs in the second decade of life. The sex distribution was almost equal in our study, as in other^.^,^,^,' The duration of these lesions varies greatly, from a few days to 3 years. Because the mucocele is a painless mass, the lesion may be left unreported for a long time. Cohen7 reported in his series that a swelling had appeared, increased in size, burst, and recurred on a number of occasions in some cases. However, in most cases in our series the size of mucoceles showed no remarkable change, and no correlation between the size and duration of a mucocele was found. The most commonly affected site of a lower lip mucocele was thought to be the area where the upper canine i m ~ i n g e d .In ~ our study, the area opposite the upper lateral incisor was involved in 50 of 71 mucoceles. The upper canine was thought to be the causative factor in only 12 mucoceles. Three cases occurred in the midline, and side incidence was almost equally divided between left and right. Oral mucoceles are usually small, commonly Lower Lip Mucoceles
less than 10 mm. The larger lesions are prone to occur in the lower lip and cheek." About 75% of our 71 mucoceles were smaller than 10 mm; the diameter of the biggest one was 25 mm. The specimens commonly presented the characteristic histologic picture of a mucous extravasation cyst: a sac lined with granulation or fibrous tissue or both. Only 2 of 70 mucoceles had an epithelial lining. Harrison" collected 400 cases of oral mucoceles and showed that 40 of them were mucousretention cysts. In Harrison's series, only 1 of 259 lower lip mucoceles was a mucous retention cyst. The high frequency of trauma t o the lower lip is well known, and the fact that most of the mucoceles on the lower lip are mucous extravasation cysts substantiates the role of trauma as the causative factor. Experimentally, Bhaskar et al.13 and Chaudhry et al.5 found that when the salivary gland ducts of mice and rats were severed, lesions similar to human mucoceles developed. Furthermore, Harrison and Garrett14 produced mucous extravasation with mucocele formation by ductal ligation, avoiding damage to the innervation of the salivary gland in cats; they suggested that HEAD & NECK
JulyIAugust 1990
319
complete ductal obstruction was a possible etiological factor in mucocele formation. In Sela and Ulmansky's' report, calculus was found in the dilated salivary gland duct belonging to a mucous retention cyst, which seemed to substantiate the suggestion of Harrison and Garrett.I4 There are 2 important factors in the etiology of a mucocele: ductal obstruction and trauma. The former seems to result in ductal dilatation leading to an epithelium-lined retention cyst; the latter, in mucous escape into the connective tissue leading to a mucous extravasation cyst. Several methods have been applied in the
treatment of mucoceles. Surgical removal is the treatment of choice, because recurrence is quite rare. Other methods, such as cryosurgery and local injection of steroids, are associated with a higher frequency of recurrence.15 In surgical intervention, it is important t o avoid creating a deformity of the lower lip. Different techniques may be applied depending on the size of the lesion. Local excision is recommended for superficial mucoceles, and enucleation for deeper ones. With either technique, it is important to remove not only the mucocele but also the surrounding minor salivary gland tissue.
REFERENCES
1. Bouquot JE, Gundlach KK. Oral exophytic lesions i n 23,616 white Americans over 35 years of age. Oral Surg Oral Med Oral Pathol 1986;62:284-291. 2. Bhaskar SN, Bolden TE, Weinmann J P . Pathogenesis of mucoceles. J Dent Res 1956;35:863- 874. 3. MGller JF. Mucosacyster i Mundhulen. Tandlaegebl 1958;62:263-272. 4. Standish SM, Shafer WG. The mucus retention phenomenon. J Oral Surg 1959;17:15-22. 5. Chaudhry AF', Reynolds DH, LaChapelle CF, Vickers RA. A clinical and experimental study of mucocele (retention cyst). J Dent Res 1960;39:1253-1262. 6. Robinson L, H~flrting-HansenE. Pathologic changes associated with mucous retention cysts of minor salivary glands. Oral Surg Oral Med Oral Pathol 1964;18:191205. 7. Cohen L. Mucoceles of the oral cavity. Oral Surg Oral Med Oral Pathol 1965;19:365-372. 8. Sela J , Ulmansky M. Mucous retention cyst of salivary glands. J Oral Surg 1969;27:619-623.
320
Lower Lip Mucoceles
'9. Cataldo E, Mosadomi A. Mucoceles of the oral mucous membrane. Arch Otolaryngol 1970;91:360-365. 10. Harrison JD. Salivary mucoceles. Oral Surg Oral Med Oral Pathol 1975;39:268-278. 11. Ishida S. Clinical and histological studies of oral mucous 1980;47:447-464. cyst. J Jpn Stomatol SOC 12. Seifert G, Donath K, von Gumberz C. Mucozelen der klein speicheldrusen. Extravasations-Mucozelen (Schleimgranulome) und Retentions-Mucozelen (Scleim-Retentionscysten). HNO 1981;29:179- 191. 13. Bhaskar SN, Bolden TE, Weinmann JP. Experimental obstruction adenitis in the mouse. J Dent Res 1956;35:852-862. 14. Harrison JD, Garrett J R . Mucocele formation in cats by glandular duct ligation. Arch Oral Biol 1972;17:14031414. 15. Saza H, Shinohara M, Tomoyose YH, Tashiro H, Oka M. Clinico-statistical study of salivary mucoceles. Jpn J Oral Surg 1982;28:1545- 1550.
HEAD & NECK
July/August 1990
We reviewed 70 patients with lower lip mucoceles for patient characteristics, clinical features, and histopathologic findings. These cases represented approximately 75% of oral mucoceles seen in the Department of Otolaryngology, Takeda General Hospital, between February 1985 and July 1988. Patients were divided almost equally between males and females, with ages ranging from 2 to 63 years, with the highest incidence of lesions occurring in the second decade. Duration of the lesions varied greatly from a few days to 3 years, with no correlation to size. The most commonly affected site was opposite the upper lateral incisor, with the incidence divided almost equally between right and left side. Of 70 biopsies, 68 were mucous extravasation cysts and 2 were mucous retention cysts. Surgical excision was the treatment of choice, with recurrence of the lesion in only 2 cases. HEAD 81 NECK 12:316-320, 1990
Mucoceles are common lesions of the oral mucous membrane involving minor salivary gland tissue. The lower lip is the site most frequently affected. In the past, oral mucoceles were thought to
From the Department of Otolaryngology (Drs. Yarnasoba. Tayama. and Syoli), Faculty of Medicine. Universlty of Tokyo, Tokyo, Japan, and Department of Otolaryngology (Dr Fukuta), Takeda General Hospital. Fukushima, Japan. Acknowledgment. We thank Professor Y Nornura for his advice and the operating theatre staff at Takeda General Hospital for helping with the project. Address reprints requests to Dr Yamasoba at the Department of Otolaryngology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunyo-ku. Tokyo 113, Japan. Accepted for publicallon November 6, 1989
CCC 0148-6403/90/040316-05 $04 00 0 1990 John Wiley & Sons, Inc.
316
Lower Lip Mucoceles
arise from obstruction of an excretory duct, which caused back pressure of mucus and the formation of an epithelial-lined cyst. It is now, however, generally accepted that most mucoceles are caused by trauma-injury or severing of an excretory duct and subsequent escape of mucus into the adjacent tissue. Histopathologically, there are two types of mucoceles: mucous extravasation cysts and mucous retention cysts. The present series of 70 patients is reported for comparison with previous studies in terms of patient age and sex, site of lesion, and histologic features.
MATERIALS AND METHODS
We studied 70 patients with lower lip mucoceles, including 1 patient with 2 lesions, who were treated in the Department of Otolaryngology, Takeda General Hospital, between February 1985 and July 1988. Patient age and sex, site of lesion, time elapsed after onset, clinical description, and histopathologic findings were recorded for all cases. All lesions were removed surgically except for one, which ruptured due to lip-biting and healed on its own. Enucleation was performed for 20 lesions and local excision together with surrounding tissue for 50 lesions. The enucleation technique was used for the larger and deeper lesions, which were not close t o the mucous membrane. After enucleation of the lesion, the minor salivary glands exposed to the surgical area were reHEAD & NECK
July/August 1990
moved. Smaller lesions, and those located just beneath the mucous membrane, were locally excised by making a spindle-shaped incision extending laterally the length of the diameter of the mucocele on both sides. RESULTS
During the 3.5-year period of this study, the total number of oral mucoceles encountered was 92. The percentage of lower lip mucoceles was 76%; the remainder were located in the oral cavity. Of the 70 patients with lower lip mucoceles, 32 were male and 38 female. The youngest patient was 2 years old, and the oldest was 63. The highest incidence occurred in the second decade: 70% of the lower lip mucoceles occurred in patients less than 20 years of age. The duration of lower lip mucoceles varied greatly, from a few days to 3 years. In 8 cases, the duration of the lesion was not stated. Of the 62 cases, in which the duration was recorded, 47 lesions had been present for less than 3 months. No correlation between duration and the size of the mucocele was found. The lesions were commonly painless, freely movable, smooth, soft, and fluctuant. In some cases, the surface was irregular and coated due to several ruptures caused by lip-biting or puncture. The color was dependent on the depth at which the mucus accumulated in the tissue. Superficial lesions usually showed a translucent blue protrusion. The mucosal surface of a deep lesion showed a n almost normal appearance. The size varied from a few millimeters to 25 mm; in 53 lesions, the diameter was less than 10 mm. With regard to the location of the lesion, 50 mucoceles occurred at the area where the upper lateral incisor impinged against the lower lip. The area opposite the canine was affected in 12 cases. Three lesions were found at midline, and the incidence at the side was about the same (Table 1). The lesions were all surgically removed except for that in 1 patient, whose mucocele was ruptured by lip-biting. However, the ruptured lesion healed itself, and no recurrence was found during the following 2 years. Of the surgically removed ones, only 2 cases which were treated by enucleation recurred, and in these 2 cases the lesions were locally excised and healed without recurrence for 2 years. In none of the operated cases did any deformity of the lip occur. Lower Lip Mucoceles
Table 1. Site of lower lip mucoceles. No. of cases
Site Right: opposite to upper canine Lateral incisor Central incisor Left: opposite to upper canine Lateral incisor Central incisor Midline
6
27 3 6 23 3 3
nistology. The specimens seldom presented the characteristic histologic picture of a true cyst lined with an epithelium. Only 2 of 70 biopsies revealed an epithelial lining (Figure 1).None of the remaining 68 cysts had epithelial linings, although the ductal epithelium was adjacent to the connective tissue capsule in 3 cases. The walls of these specimens were usually composed of granulation or fibrous tissue or a mixture of the two. The cyst area of the mucocele usually contained an eosinophilic homogeneous mucoid material and scattered inflammatory cells with a predominance of histocytes (Figure 2). In some cases, a discrete, well-defined cystic structure was lacking and a scattered area of mucus in the surrounding connective tissue was found. In most instances, the lesions were surrounded by salivary gland tissue, which showed varying degrees of inflammation and ductal dilatation. Salivary gland tissue was always located in the submucosal layer, and the mucocele was adjacent to it. Superficial mucoceles close to the mucous membrane were located between the mucous membrane and salivary gland tissue, as shown in Figure 1A. Deeper cysts were situated below salivary gland tissue, as shown in Figure 2A. No correlation could be shown between the duration of the lesion and the changes in the salivary gland tissue. DISCUSSION
Bouquot et al.' studied the epidemiology of benign oral masses in 23,616 persons over 35 years of age and stated that the prevalence of all oral mucoceles was 2.5 lesions/1,000 population. The lower lip is the most frequently encountered site (Table 2); the remainder occur in the cheek, palate, floor of the mouth, tongue, and retromolar fossa. The upper lip is rarely affected. Mucoceles occur most often in children and young adults. Histopathologically, there are 2 types of mucoceles: mucous extravasation cysts HEAD 8, NECK
July/August 1990
317
A
FIGURE 1. (A) Low-power view of a mucous retention cyst with columnar epithelium lining. The superficial cyst is located between the mucous membrane and minor salivary gland tissue. Hematoxylin & eosin, x 15, original magnification. (B) High-power view of a mucous retention cyst. Stratified columnar epithelium is found. Hematoxylin 8 eosin, x250, original magnification.
Table 2. Percentage of lip mucoceles. Lower lip Author Bhaskar et a1.‘ M0l1er3 Standish and Shafer4 Chaudhry et al.5 Robinson and Hjmting-Hansen‘ Cohen’ Sela and Ulmansky’ Cataldo and Mosadomig Harrison” Ishida” Seiferi et a!.’’ Saza et ai.15 Bouquot et a1.l Yamasoba et al. (present study)
318
Lower Lip Mucoceles
Year
No. of oral mucoceles
No.
(1956) (1958) (1959) (1960) (1964) (1965) (1969) (1970) (1975) (1980) (1981) (1982) (1986) (1989)
19 44 97 66 125 82 29 594 55 425 273 385 59 92
11 31 43 45 64 52 21 348 33 336 197 208 33 70
%
Upper lip No.
HEAD & NECK
%
JulylAugust 1990
A
B
FIGURE 2. (A) Low-power view of a mucous extravasation cyst with a wall composed of fibrous tissue. The deep cyst is located below minor salivary gland tissue. Hematoxylin & eosin, x 15, original magnification. (6) High-power view of a mucous extravasation cyst. Note the lack of epithelium. Hematoxylin & eosin, x250, original magnification.
and mucous retention cysts. The latter occur most often in older and account for a small percentage of mucoceles. The highest incidence of the lesion occurs in the second decade of life. The sex distribution was almost equal in our study, as in other^.^,^,^,' The duration of these lesions varies greatly, from a few days to 3 years. Because the mucocele is a painless mass, the lesion may be left unreported for a long time. Cohen7 reported in his series that a swelling had appeared, increased in size, burst, and recurred on a number of occasions in some cases. However, in most cases in our series the size of mucoceles showed no remarkable change, and no correlation between the size and duration of a mucocele was found. The most commonly affected site of a lower lip mucocele was thought to be the area where the upper canine i m ~ i n g e d .In ~ our study, the area opposite the upper lateral incisor was involved in 50 of 71 mucoceles. The upper canine was thought to be the causative factor in only 12 mucoceles. Three cases occurred in the midline, and side incidence was almost equally divided between left and right. Oral mucoceles are usually small, commonly Lower Lip Mucoceles
less than 10 mm. The larger lesions are prone to occur in the lower lip and cheek." About 75% of our 71 mucoceles were smaller than 10 mm; the diameter of the biggest one was 25 mm. The specimens commonly presented the characteristic histologic picture of a mucous extravasation cyst: a sac lined with granulation or fibrous tissue or both. Only 2 of 70 mucoceles had an epithelial lining. Harrison" collected 400 cases of oral mucoceles and showed that 40 of them were mucousretention cysts. In Harrison's series, only 1 of 259 lower lip mucoceles was a mucous retention cyst. The high frequency of trauma t o the lower lip is well known, and the fact that most of the mucoceles on the lower lip are mucous extravasation cysts substantiates the role of trauma as the causative factor. Experimentally, Bhaskar et al.13 and Chaudhry et al.5 found that when the salivary gland ducts of mice and rats were severed, lesions similar to human mucoceles developed. Furthermore, Harrison and Garrett14 produced mucous extravasation with mucocele formation by ductal ligation, avoiding damage to the innervation of the salivary gland in cats; they suggested that HEAD & NECK
JulyIAugust 1990
319
complete ductal obstruction was a possible etiological factor in mucocele formation. In Sela and Ulmansky's' report, calculus was found in the dilated salivary gland duct belonging to a mucous retention cyst, which seemed to substantiate the suggestion of Harrison and Garrett.I4 There are 2 important factors in the etiology of a mucocele: ductal obstruction and trauma. The former seems to result in ductal dilatation leading to an epithelium-lined retention cyst; the latter, in mucous escape into the connective tissue leading to a mucous extravasation cyst. Several methods have been applied in the
treatment of mucoceles. Surgical removal is the treatment of choice, because recurrence is quite rare. Other methods, such as cryosurgery and local injection of steroids, are associated with a higher frequency of recurrence.15 In surgical intervention, it is important t o avoid creating a deformity of the lower lip. Different techniques may be applied depending on the size of the lesion. Local excision is recommended for superficial mucoceles, and enucleation for deeper ones. With either technique, it is important to remove not only the mucocele but also the surrounding minor salivary gland tissue.
REFERENCES
1. Bouquot JE, Gundlach KK. Oral exophytic lesions i n 23,616 white Americans over 35 years of age. Oral Surg Oral Med Oral Pathol 1986;62:284-291. 2. Bhaskar SN, Bolden TE, Weinmann J P . Pathogenesis of mucoceles. J Dent Res 1956;35:863- 874. 3. MGller JF. Mucosacyster i Mundhulen. Tandlaegebl 1958;62:263-272. 4. Standish SM, Shafer WG. The mucus retention phenomenon. J Oral Surg 1959;17:15-22. 5. Chaudhry AF', Reynolds DH, LaChapelle CF, Vickers RA. A clinical and experimental study of mucocele (retention cyst). J Dent Res 1960;39:1253-1262. 6. Robinson L, H~flrting-HansenE. Pathologic changes associated with mucous retention cysts of minor salivary glands. Oral Surg Oral Med Oral Pathol 1964;18:191205. 7. Cohen L. Mucoceles of the oral cavity. Oral Surg Oral Med Oral Pathol 1965;19:365-372. 8. Sela J , Ulmansky M. Mucous retention cyst of salivary glands. J Oral Surg 1969;27:619-623.
320
Lower Lip Mucoceles
'9. Cataldo E, Mosadomi A. Mucoceles of the oral mucous membrane. Arch Otolaryngol 1970;91:360-365. 10. Harrison JD. Salivary mucoceles. Oral Surg Oral Med Oral Pathol 1975;39:268-278. 11. Ishida S. Clinical and histological studies of oral mucous 1980;47:447-464. cyst. J Jpn Stomatol SOC 12. Seifert G, Donath K, von Gumberz C. Mucozelen der klein speicheldrusen. Extravasations-Mucozelen (Schleimgranulome) und Retentions-Mucozelen (Scleim-Retentionscysten). HNO 1981;29:179- 191. 13. Bhaskar SN, Bolden TE, Weinmann JP. Experimental obstruction adenitis in the mouse. J Dent Res 1956;35:852-862. 14. Harrison JD, Garrett J R . Mucocele formation in cats by glandular duct ligation. Arch Oral Biol 1972;17:14031414. 15. Saza H, Shinohara M, Tomoyose YH, Tashiro H, Oka M. Clinico-statistical study of salivary mucoceles. Jpn J Oral Surg 1982;28:1545- 1550.
HEAD & NECK
July/August 1990
