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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.
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