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Dentomaxillofacial Radiology (2009) 38, 121–124 ’ 2009 The British Institute of Radiology http://dmfr.birjournals.org CASE REPORT Bilateral submandibular gland aplasia with clinico-radiological mass due to prolapsing sublingual salivary tissue through mylohyoid boutonnière: a case report and review M Ahmed*,1, M Strauss2, A Kassaie1, V Shotelersuk1 and R DeGuzman1 1 Department of Radiology, Louis Stokes VA Medical Center, Cleveland, OH, USA; 2Department of Otorhinolaryngology, Louis Stokes VA Medical Center, Cleveland, OH, USA Aplasia of major salivary glands is very rare. Compensatory hypertrophy of the rest of the glands can result in clinico-radiological masses. We present a report of a rare case of nonsyndromic bilateral submandibular gland aplasia with hypertrophied sublingual salivary tissue, the latter herniating through mylohyoid boutonnière to present as a palpable mass on the left side with corresponding CT findings. Multiplanar evaluation is emphasised by utilizing multidetector CT. Dentomaxillofacial Radiology (2009) 38, 121–124. doi: 10.1259/dmfr/63254814 Keywords: submandibular, aplasia, mylohyoid, boutonnière, multidetector computed tomography Case report A 62-year-old African American male was referred to the ear, nose and throat (ENT) outpatient clinic in our hospital by his primary care physician for the evaluation of a left submandibular mass, noted on a routine physical examination. Given the previous history of smoking and a family history of cancer, metastatic lymphadenopathy from primary head and neck cancer was the main consideration. The patient denied any relevant symptoms. There was no history of prior head and neck surgery or cancer. The ENT examination was negative except for a left-sided, palpable, non-tender, firm mobile mass. Fine needle aspiration for cytology was attempted, but was unsuccessful. A routine CT of the soft tissue of the neck with intravenous contrast was performed with review of conventional axial images plus multiplanar reconstructions. No soft-tissue neckmasses or pathological lymphadenopathy were present. However, bilateral enhancing hypertrophied sublingual salivary tissue was identified and noted to prolapse through mylohyoid defects (left more than right) into the superficial submandibular space. Bilateral parotid glands were of normal size and attenuation while *Correspondence to: Dr Manzoor Ahmed, 10701 East Boulevard, Louis Stokes VA Medical Center, Radiology Department R/No. G23, Cleveland, OH 44141, USA; E-mail: [email protected] or [email protected] Received 30 September 2007; revised 25 February 2008; accepted 30 March 2008 submandibular glands were not visualized; in their place, only facial vessels and or lymph nodes were present (Figures 1 and 2). Discussion Aplasia of one or more of the major salivary glands is very rare.1,2 The parotid gland is more commonly affected than the submandibular glands according to the literature.3,4 Aplasia of a combination of major salivary glands with other glands (such as lacrimal and thyroid glands) is seen with congenital disorders such as lacrimoauriculodentodigital (LADD) syndrome, mandibulofacial dysostosis and ectodermal dysplasia.5–7 Isolated cases of bilateral submandibular gland aplasia are extremely rare. Compensatory hypertrophy of the contralateral or other major salivary glands, or accessory salivary tissue, can result in clinical and/or radiological pseudomasses.8 Herniation of the hypertrophied sublingual salivary tissue through anterior mylohyoid muscular defect masqueraded as a left-sided submandibular mass in our case. To the best of our knowledge, there are no previous reports to be found in the literature with a combination of such findings. Patients with salivary gland aplasia are mostly asymptomatic, unless the physiological dysfunction is severe enough by virtue of a lack of significant Bilateral submandibular gland aplasia M Ahmed et al 122 a b c Figure 1 Axial source images post-contrast CT soft-tissue neck. Bilateral hypertrophied sublingual salivary tissue (solid white arrows), prolapsing through bilateral anterior mylohyoid muscular defects (dotted lines in (a,b)), larger on the left side. Only facial vessels (dashed arrows in (a,b)) and lymph node (dashed arrow in (c)) present at the expected location for submandibular glands. Note mylohyoid (dark arrow in (a)) and anterior belly of digastric muscles at floor of mouth (dotted lines in (c)) contrast (even without intravenous contrast) and multiplanar capability by virtue of multidetector CT (MDCT) technology. Using the spiral acquisition mode on the MDCT scanner, thinner axial slices that have overlapped can be retrospectively reconstructed for better multiplanar and three-dimensional reconstructions (as we did in our case). The multiplanar capability and superior soft-tissue resolution of MRI can be utilized to clearly depict findings in such cases. Ultrasound is preferred in some institutions for head and neck imaging, and in experienced hands can be used to demonstrate salivary gland aplasia and hypertrophy. Submandibular glands normally wrap around the posterior margin of the mylohyoid muscle, resulting in a superficial and deeper portion of the gland. The other compensatory hypertrophy of the other salivary glands or accessory tissue.1,9 Paradoxically, the presence of the latter can cause a clinical or radiological mass (as in our case). Clinical sequela of major salivary gland aplasia includes xerostomia, dental disease, ascending sialadenitis and recurrent oral and oropharyngeal inflammation.2,10–12 Clinical diagnostic tools include a search for major glandular duct orifices, stimulated mouth salivary flow (sialometry) and Schirmer’s test (for lacrimation).1 Labial or parotid biopsy have been used in the past to exclude Sjogren’s syndrome.1,13 Salivary gland scintigraphy will certainly show absence of activity in the aplastic glands.1,3 However, soft-tissue CT of the neck can serve as the single procedure for definitive diagnosis due to its easy accessibility, speed, acceptable soft-tissue a b c Figure 2 Multiplanar reformatted CT images in (a) coronal, (b) oblique sagittal and (c) oblique coronal planes. Bilateral prolapsing sublingual salivary tissue (solid arrows) through mylohyoid defects (dotted arrows) are better demonstrated. Note bilateral normal parotid glands (marked as P in (a)) Dentomaxillofacial Radiology Bilateral submandibular gland aplasia M Ahmed et al consistent imaging marker of the submandibular gland’s normal location is its close relationship to the facial artery and vein. Our case shows no imaging evidence of typical submandibular gland or enhancing salivary tissue. As in previously reported cases, the submandibular space was replaced by facial vessels and small lymph nodes. Defects or boutonnières in the mylohyoid muscles have a high prevalence, ranging from 30% to 80%, as shown in cadaver and imaging studies.14–20 The mylohyoid muscle forms the floor of the mouth, supporting the tongue and defining the boundary between the submandibular and sublingual space. The muscle itself consists of anterior and posterior parts on each side. The posterior portions attach to the body of the hyoid bone, while the middle and anterior fibres attach to the fibrous median raphe that runs from the mandibular symphysis to the hyoid bone. The defect appears as a transverse fissure between the fibres, or as a broader round or oval opening. The base of the opening may be constricted or broad.14 The defects are usually small (less than 5 mm), but sometimes larger than 2 cm.14,16 Defects are generally not visible in the thicker, posterior third of the muscle. The defects are bilateral in two-thirds of cases (as in our case) with fat as the most common constituent, followed by blood vessels and then accessory salivary tissue.16 Enlargement of the major salivary glands due to hypertrophy of histopathologically normal-appearing salivary tissue is known as sialosis.21,22 Sialosis can be idiopathic or associated with malnutrition, diabetes, bulimia or alcoholism.21,22 Compensatory hypertrophy of primary or accessory salivary tissues, on the other hand, is triggered by a congenital or acquired absence of other salivary glands. Compensatory enlargement of parotid glands or malar accessory parotid tissue have been most commonly reported and studied in the setting of aplasia, resection or denervation of parotid or other major salivary glands.23–27 Accessory sublingual salivary tissue, as alluded to before, is seen at the mylohyoid 123 boutonnière16 and was initially referred to as a ‘‘bouton of sublingual gland’’.17 Terming it as ‘‘accessory sublingual gland or tissue’’ will actually be a misnomer as Engel at al18 showed a nearly-equal incidence of sublingual (mucous-type salivary gland tissue) and submandibular histological features (mucous–serous with serous predominance) in the salivary tissue found at mylohyoid defects. White et al16 have shown on imaging that accessory salivary tissue along mylohyoid muscles is virtually not seen without the presence of muscular defects or boutonnières. In contrast to accessory salivary tissue, there are only a few reported cases that specifically describe herniation of the proper sublingual glands through mylohyoid defects.19,20 Functional MRI (preferably in the coronal plane) using the modified Valsalva manoeuvre can cause herniation of sublingual tissues, including normal or enlarged sublingual glands, through the mylohyoid defect, thus unmasking the clinically palpable mass on imaging.15,19 Our case also shows bilateral large sublingual glands rather than discrete accessory tissue herniating through the mylohyoid defect. To the best of our knowledge, we are not aware of any reported case showing the combined findings of bilateral hypertrophied sublingual salivary glands due to aplasia of other major glands and herniation through mylohyoid defects, thus presenting as radiological and clinical masses. However, Srinivisan et al8 recently reported a case of unilateral submandibular gland aplasia with ipsilateral hypertrophied sublingual gland. Unlike our case, their patient did not present with a clinically palpable mass. In summary, isolated major salivary gland aplasia is very rare. Associated hypertrophy of proper glands or accessory salivary tissue should be included in the differential of palpable masses, which manifests like typical salivary tissue on imaging. Mylohyoid boutonnière can provide a window for sublingual space masses to prolapse into submandibular space including hypertrophied salivary tissue. References 1. Yoshiura K, Yamada M, Yamada N. Demonstration of congenital absence of the major salivary glands by computed tomography. Dentomaxillofac Radiol 1990; 2: 77–78. 2. Gelbier MJ, Winter GB. Absence of salivary glands in children with rampant dental caries: report of seven cases. Int J Paediatr Dent 1995; 5: 253–257. 3. 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