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Accessory Duct in the Submandibular Gland
Asian Accessory J Oral Duct Maxillofac in Submandibular Surg. 2007;19:110-2. Gland
CASE REPORT
Accessory Duct in the Submandibular Gland Norio Kuroyanagi,1 Hiroyuki Kinoshita,2 Junichiro Machida,1 Shintaro Suzuki,3 Yutaka Yamada2 1 Department of Oral and Maxillofacial Surgery-II, Aichi-Gakuin University School of Dentistry, Aichi, 2Department of Oral and Maxillofacial Surgery, Okazaki City Hospital, Aichi, and 3 Department of Oral and Maxillofacial Surgery, Toyokawa City Hospital, Aichi, Japan
Abstract A 26-year-old woman with duplication of the submandibular duct, noted on sialographic examination of the submandibular gland, is reported. Naked eye confirmation was possible on examination of the excised gland. No histological abnormality in duct structure was recognised. Key words: Abnormalities, Salivary ducts, Salivary gland neoplasms, Sialography, Submandibular gland
Introduction Approximately 5 to 13 intercalated ducts of various types are thought to join directly into the 1 main duct in the body of the submandibular gland.1 Although more than 1 duct of the major sublingual gland may be encountered in the embryonic stages, just 1 duct of the major sublingual gland or that of an accessory lobe of the submandibular gland usually joins the submandibular duct,1 and ultimately only 1 submandibular duct is usually present. In 1932, Rose2 reported a duplication anomaly of the submandibular duct. Since that time, 6 other reports of duplication of the submandibular duct have been reported.3-8 We encountered the rare case of double submandibular ducts as described below.
Case Report A 26-year-old, otherwise well, Japanese woman presented to the Okazaki City Hospital with a 3-year history of a painless swelling in the right submandibular region that appeared to be increasing in size. Palpation revealed enlargement of the right submandibular gland to about 3 cm in diameter. The gland was resilient in consistency and freely movable without tenderness. No other cervical masses or lymphadenopathies were noted. The orifice of the submandibular duct was identified and saliva secretion was determined to be normal. No abnormality was evident in the sublingual caruncle. Sialography was performed and 5 mL of urografin was injected into the right submandibular gland (Figure 1). Correspondence: Norio Kuroyanagi, Department of Oral and Maxillofacial Surgery-II, Aichi-Gakuin University School of Dentistry, 2-11 Suemori-dori, Chikusa-ku, Nagoya 464 8651, Japan. Tel: (81 52) 751 7181, ext. 294; Fax: (81 52) 752 5990; E-mail: [email protected]
110
Figure 1. Sialogram showing 2 main ducts in the right submandibular gland. The main duct that formed within the body of the submandibular gland diverged into 2 ducts running outside the gland. Both submandibular ducts displayed parallel courses under the floor of mouth. The double ducts joined together 5 mm distal to the orifice.
Lateral view of the submandibular sialogram showed apparent double main ducts smoothly displaced around a benign-appearing mass of approximately 25 mm diameter in the body of the submandibular gland. The main duct that formed within the body of the submandibular gland diverged into 2 ducts running outside the gland. Bifurcation of the duct showed slight enlargement. Both submandibular ducts ran a parallel course in the floor of mouth, and the duct running the lower course was narrower. The double ducts © 2007 AsianAsian Association J Oral Maxillofac of Oral andSurg. Maxillofacial Vol 19, No Surgeons. 2, 2007
Kuroyanagi, Kinoshita, Machida, et al
joined together 5 mm distal to the orifice and opened together into the oral cavity. The left submandibular gland was normal. The clinical diagnosis was tumour of the right submandibular gland and duplication of the submandibular duct. Excision of the tumour with the right submandibular gland was performed under general anaesthesia. After freeing the gland, 1 submandibular duct was identified at the uncinate process of the gland running inside the mylohyoid muscle. This submandibular duct was cut, after injection of the dye into the gland, to confirm anatomy. Subsequently, careful separation downwards through the connective tissue was performed to reveal the second duct of the submandibular gland emerging independently from the uncinate process of the gland (Figure 2). Adjacent to the submandibular gland was the tumour mass of about 20 mm diameter, with the second duct adherent to it. Either an accessory lobe of the submandibular gland or a lymph node
Figure 2. Stumps of the 2 ducts demonstrated after resection of tumour. Arrows point to stumps of the 2 ducts.
Figure 3. Histological examination of the excised lesion. No abnormality was recognised in duct structure (haematoxylin and eosin; original magnification, × 10). Arrows point to the submandibular ducts. Asian J Oral Maxillofac Surg. Vol 19, No 2, 2007
was suspected to explain the second mass. Hence, the second submandibular duct was cut and the tissue excised en bloc. The second stump of the duct also displayed the presence of dye. The surgical wound was closed in layers and a rubber drain was left inserted. The postoperative course was uneventful with no evidence of tumour recurrence over a 3-year follow-up. Histopathological examination identified the tumour as a pleomorphic adenoma, with the major duct dividing into 2 ducts in the body of the submandibular gland. No abnormality was recognised in the duct structure itself (Figure 3). The mass adhering to the second duct was not an accessory salivary gland, and was instead confirmed as a lymph node (Figure 4).
Discussion The duct of the submandibular gland runs from the front of the uncinate process, crosses the lingual nerve and continues medial to the sublingual gland. The duct arises from the proliferation and ingrowth of ectodermal cells in the floor of the oral cavity at about gestational week 6-7. Further differentiation takes place with the development of the acinar complexes and the ductal system until full term. The final process in duct development is the hollowing of the epithelial tissue, which allows for a patent ductal system in the floor of mouth.9 To date, congenital abnormalities of the submandibular duct, including imperforate submandibular duct and large dilatation of the duct, have been reported.2,10 However, extensive review of the literature revealed only 7 previous reports of multiple submandibular ducts.2-8 Pownell et al6 reported on the aetiology of ductal formation deformities and suggested that anomalies of the duct can result if the developing duct invaginates in 2 places or if premature ventral branching of the duct occurs with duplication.
Figure 4. The mass adhering to the second duct was not an accessory salivary gland and was confirmed as a lymph node. 111
Accessory Duct in Submandibular Gland
Adhesion of endothelium of the dilated duct might divide into a double endocavity. Extracellular matrix protein, fibronectin, is essential for cleft formation during the initiation of epithelial branching. Fibronectin mRNA appears transiently and focally in developing cleft regions of the submandibular gland epithelia accompanied by an adjacent loss of cadherin localisation.11 Cadherin is one of the most important glycoproteins that promote cell-to-cell adhesion. Similarly, it is suspected that accumulation of fibronectin or loss of cadherin localisation has a possible role in duplication of the duct. Gaur et al3 reported a submandibular gland with 3 ducts, each opening separately into the floor of the mouth. Rose2 described a submandibular duct bifurcation with the opening of the posterior limb located in the floor of the mouth opposite the second molar; however, this may have been a fistulous tract occurring behind an obstruction caused by a calculus. Incidentally, while the major sublingual duct or the duct of an accessory lobe of the submandibular gland may join the main duct outside the gland, no radiopaque stones nor mucous plugs were detected in the present case and the ducts arose inside the submandibular gland. Adhesion of the second duct to the lymph node in the submandibular region might be one of the possible factors in this anomaly. Pathological conditions of salivary glands can be evaluated using sialography. However, in case of multiple ducts opening separately, it is difficult to visualise ducts on sialography unless all are successfully injected with contrast medium. The use of sialography has decreased as less invasive examinations, such as computed tomography scans, magnetic resonance imaging, and ultrasonography have become more widely available. This suggests that, in future, identification of multiple ducts of the submandibular gland
112
might become less frequent. However, it is crucial that the operating surgeon remember the possibility of encountering multiple ducts in the submandibular gland.
Acknowledgement We would like to thank Professor Kazuo Shimozato, Department of Oral and Maxillofacial Surgery-II, AichiGakuin University School of Dentistry, for his assistance.
References 1. 2.
Kamijo Y, editor. Oral anatomy. Tokyo: Anatomy Co.; 1969:1324. Rose BH. Bifurcation of the submaxillary duct. Am J Surg. 1932;17: 257-8.
3.
Gaur U, Choudhry R, Anand C, Choudhry S. Submandibular gland with multiple ducts. Surg Radiol Anat. 1994;16:439-40.
4.
Mori S, Wada T, Harada Y, Toyoshima S. Accessory duct in the submandibular gland. Oral Surg Oral Med Oral Pathol. 1986;62:607-8.
5.
Myerson M, Crelin ES, Smith HW. Bilateral duplication of the submandibular ducts. Arch Otolaryngol. 1966;83:488-90.
6.
Pownell PH, Brown OE, Pransky SM, Manning SC. Congenital abnormalities of the submandibular duct. Int J Pediatr Otorhinolaryngol. 1992;24:161-9.
7.
Rahmathulla M. A rare case of accessory duct in sub-mandibular
8.
Towers JF. Duplication of the submandibular salivary duct. Oral Surg
9.
Harold CS. Developmental craniofacial biology. In: Ozawa H, editor.
sialography. J Indian Dent Assoc. 1973;45:563-4. Oral Med Oral Pathol. 1977;44:326. Salivary gland. Japanese ed. Niigata: Nishimura Co.; 1992:210. 10. Addante RR. Congenital cystic dilatation of submandibular duct. Oral Surg Oral Med Oral Pathol. 1984;58:656-8. 11. Sakai T, Larsen M, Yamada KM. Fibronectin requirement in branching morphogenesis. Nature. 2003;423:876-81.
Asian J Oral Maxillofac Surg. Vol 19, No 2, 2007
CASE REPORT
Accessory Duct in the Submandibular Gland Norio Kuroyanagi,1 Hiroyuki Kinoshita,2 Junichiro Machida,1 Shintaro Suzuki,3 Yutaka Yamada2 1 Department of Oral and Maxillofacial Surgery-II, Aichi-Gakuin University School of Dentistry, Aichi, 2Department of Oral and Maxillofacial Surgery, Okazaki City Hospital, Aichi, and 3 Department of Oral and Maxillofacial Surgery, Toyokawa City Hospital, Aichi, Japan
Abstract A 26-year-old woman with duplication of the submandibular duct, noted on sialographic examination of the submandibular gland, is reported. Naked eye confirmation was possible on examination of the excised gland. No histological abnormality in duct structure was recognised. Key words: Abnormalities, Salivary ducts, Salivary gland neoplasms, Sialography, Submandibular gland
Introduction Approximately 5 to 13 intercalated ducts of various types are thought to join directly into the 1 main duct in the body of the submandibular gland.1 Although more than 1 duct of the major sublingual gland may be encountered in the embryonic stages, just 1 duct of the major sublingual gland or that of an accessory lobe of the submandibular gland usually joins the submandibular duct,1 and ultimately only 1 submandibular duct is usually present. In 1932, Rose2 reported a duplication anomaly of the submandibular duct. Since that time, 6 other reports of duplication of the submandibular duct have been reported.3-8 We encountered the rare case of double submandibular ducts as described below.
Case Report A 26-year-old, otherwise well, Japanese woman presented to the Okazaki City Hospital with a 3-year history of a painless swelling in the right submandibular region that appeared to be increasing in size. Palpation revealed enlargement of the right submandibular gland to about 3 cm in diameter. The gland was resilient in consistency and freely movable without tenderness. No other cervical masses or lymphadenopathies were noted. The orifice of the submandibular duct was identified and saliva secretion was determined to be normal. No abnormality was evident in the sublingual caruncle. Sialography was performed and 5 mL of urografin was injected into the right submandibular gland (Figure 1). Correspondence: Norio Kuroyanagi, Department of Oral and Maxillofacial Surgery-II, Aichi-Gakuin University School of Dentistry, 2-11 Suemori-dori, Chikusa-ku, Nagoya 464 8651, Japan. Tel: (81 52) 751 7181, ext. 294; Fax: (81 52) 752 5990; E-mail: [email protected]
110
Figure 1. Sialogram showing 2 main ducts in the right submandibular gland. The main duct that formed within the body of the submandibular gland diverged into 2 ducts running outside the gland. Both submandibular ducts displayed parallel courses under the floor of mouth. The double ducts joined together 5 mm distal to the orifice.
Lateral view of the submandibular sialogram showed apparent double main ducts smoothly displaced around a benign-appearing mass of approximately 25 mm diameter in the body of the submandibular gland. The main duct that formed within the body of the submandibular gland diverged into 2 ducts running outside the gland. Bifurcation of the duct showed slight enlargement. Both submandibular ducts ran a parallel course in the floor of mouth, and the duct running the lower course was narrower. The double ducts © 2007 AsianAsian Association J Oral Maxillofac of Oral andSurg. Maxillofacial Vol 19, No Surgeons. 2, 2007
Kuroyanagi, Kinoshita, Machida, et al
joined together 5 mm distal to the orifice and opened together into the oral cavity. The left submandibular gland was normal. The clinical diagnosis was tumour of the right submandibular gland and duplication of the submandibular duct. Excision of the tumour with the right submandibular gland was performed under general anaesthesia. After freeing the gland, 1 submandibular duct was identified at the uncinate process of the gland running inside the mylohyoid muscle. This submandibular duct was cut, after injection of the dye into the gland, to confirm anatomy. Subsequently, careful separation downwards through the connective tissue was performed to reveal the second duct of the submandibular gland emerging independently from the uncinate process of the gland (Figure 2). Adjacent to the submandibular gland was the tumour mass of about 20 mm diameter, with the second duct adherent to it. Either an accessory lobe of the submandibular gland or a lymph node
Figure 2. Stumps of the 2 ducts demonstrated after resection of tumour. Arrows point to stumps of the 2 ducts.
Figure 3. Histological examination of the excised lesion. No abnormality was recognised in duct structure (haematoxylin and eosin; original magnification, × 10). Arrows point to the submandibular ducts. Asian J Oral Maxillofac Surg. Vol 19, No 2, 2007
was suspected to explain the second mass. Hence, the second submandibular duct was cut and the tissue excised en bloc. The second stump of the duct also displayed the presence of dye. The surgical wound was closed in layers and a rubber drain was left inserted. The postoperative course was uneventful with no evidence of tumour recurrence over a 3-year follow-up. Histopathological examination identified the tumour as a pleomorphic adenoma, with the major duct dividing into 2 ducts in the body of the submandibular gland. No abnormality was recognised in the duct structure itself (Figure 3). The mass adhering to the second duct was not an accessory salivary gland, and was instead confirmed as a lymph node (Figure 4).
Discussion The duct of the submandibular gland runs from the front of the uncinate process, crosses the lingual nerve and continues medial to the sublingual gland. The duct arises from the proliferation and ingrowth of ectodermal cells in the floor of the oral cavity at about gestational week 6-7. Further differentiation takes place with the development of the acinar complexes and the ductal system until full term. The final process in duct development is the hollowing of the epithelial tissue, which allows for a patent ductal system in the floor of mouth.9 To date, congenital abnormalities of the submandibular duct, including imperforate submandibular duct and large dilatation of the duct, have been reported.2,10 However, extensive review of the literature revealed only 7 previous reports of multiple submandibular ducts.2-8 Pownell et al6 reported on the aetiology of ductal formation deformities and suggested that anomalies of the duct can result if the developing duct invaginates in 2 places or if premature ventral branching of the duct occurs with duplication.
Figure 4. The mass adhering to the second duct was not an accessory salivary gland and was confirmed as a lymph node. 111
Accessory Duct in Submandibular Gland
Adhesion of endothelium of the dilated duct might divide into a double endocavity. Extracellular matrix protein, fibronectin, is essential for cleft formation during the initiation of epithelial branching. Fibronectin mRNA appears transiently and focally in developing cleft regions of the submandibular gland epithelia accompanied by an adjacent loss of cadherin localisation.11 Cadherin is one of the most important glycoproteins that promote cell-to-cell adhesion. Similarly, it is suspected that accumulation of fibronectin or loss of cadherin localisation has a possible role in duplication of the duct. Gaur et al3 reported a submandibular gland with 3 ducts, each opening separately into the floor of the mouth. Rose2 described a submandibular duct bifurcation with the opening of the posterior limb located in the floor of the mouth opposite the second molar; however, this may have been a fistulous tract occurring behind an obstruction caused by a calculus. Incidentally, while the major sublingual duct or the duct of an accessory lobe of the submandibular gland may join the main duct outside the gland, no radiopaque stones nor mucous plugs were detected in the present case and the ducts arose inside the submandibular gland. Adhesion of the second duct to the lymph node in the submandibular region might be one of the possible factors in this anomaly. Pathological conditions of salivary glands can be evaluated using sialography. However, in case of multiple ducts opening separately, it is difficult to visualise ducts on sialography unless all are successfully injected with contrast medium. The use of sialography has decreased as less invasive examinations, such as computed tomography scans, magnetic resonance imaging, and ultrasonography have become more widely available. This suggests that, in future, identification of multiple ducts of the submandibular gland
112
might become less frequent. However, it is crucial that the operating surgeon remember the possibility of encountering multiple ducts in the submandibular gland.
Acknowledgement We would like to thank Professor Kazuo Shimozato, Department of Oral and Maxillofacial Surgery-II, AichiGakuin University School of Dentistry, for his assistance.
References 1. 2.
Kamijo Y, editor. Oral anatomy. Tokyo: Anatomy Co.; 1969:1324. Rose BH. Bifurcation of the submaxillary duct. Am J Surg. 1932;17: 257-8.
3.
Gaur U, Choudhry R, Anand C, Choudhry S. Submandibular gland with multiple ducts. Surg Radiol Anat. 1994;16:439-40.
4.
Mori S, Wada T, Harada Y, Toyoshima S. Accessory duct in the submandibular gland. Oral Surg Oral Med Oral Pathol. 1986;62:607-8.
5.
Myerson M, Crelin ES, Smith HW. Bilateral duplication of the submandibular ducts. Arch Otolaryngol. 1966;83:488-90.
6.
Pownell PH, Brown OE, Pransky SM, Manning SC. Congenital abnormalities of the submandibular duct. Int J Pediatr Otorhinolaryngol. 1992;24:161-9.
7.
Rahmathulla M. A rare case of accessory duct in sub-mandibular
8.
Towers JF. Duplication of the submandibular salivary duct. Oral Surg
9.
Harold CS. Developmental craniofacial biology. In: Ozawa H, editor.
sialography. J Indian Dent Assoc. 1973;45:563-4. Oral Med Oral Pathol. 1977;44:326. Salivary gland. Japanese ed. Niigata: Nishimura Co.; 1992:210. 10. Addante RR. Congenital cystic dilatation of submandibular duct. Oral Surg Oral Med Oral Pathol. 1984;58:656-8. 11. Sakai T, Larsen M, Yamada KM. Fibronectin requirement in branching morphogenesis. Nature. 2003;423:876-81.
Asian J Oral Maxillofac Surg. Vol 19, No 2, 2007