A Phlebolith in the Anterior Portion of the Masseter Muscle

Tokai J Exp Clin Med., Vol. 37, No. 1, pp. 25-29, 2012
A Phlebolith in the Anterior Portion of the Masseter Muscle
Hisashi KATO*1, Yoshihide OTA*1, Masashi SASAKI*2,
Toshihiro ARAI*1, Yasutomo SEKIDO*3 and Keiichi TSUKINOKI*4
Department of Oral and Maxillofacial Surgery, Tokai University School of Medicine
*2
Department of Oral and Maxillofacial Surgery, National Hospital Organization
Shizuoka Medical Center
*3
Department of Pathology, Tokai University School of Medicine
*4
Department of Diagnostic Science Division of Pathology, Kanagawa Dental College
*1
(Received January 12, 2012; Accepted February 20, 2012)
The differential diagnosis of a buccal soft tissue mass containing calcified bodies includes a phlebolith associated with a vascular lesion, such as a hemangioma with a calcified intravascular thrombus, and diseases
such as sialolithiasis, traumatic myositis ossificans, calcified acne lesion, neoplasm, and calcified lymph
nodes, including tuberculosis. The appearance of the calcified bodies on plain radiographs may help to differentiate these entities. Computed tomography, magnetic resonance imaging, and ultrasonography are also
useful for differentiating the soft tissue lesions.
We report a 17-year-old girl with a small mass containing a calcified body in the anterior portion of the
masseter muscle. The mass was resected surgically and evaluated histologically, confirming the diagnosis of
phlebolith. We also discuss the differential diagnosis of a buccal soft tissue mass containing calcifications
and suggest that the immunolocalization of CD31 at capillaries in the mass may help to diagnose as a phlebolith.
Key words: phlebolith, calcified body, buccal soft tissue mass, intravascular thrombus,hemangioma
INTRODUCTION
CASE REPORT
The pathological calcification of soft tissues occurs
when calcium and other mineral salts are deposited in
a tissue or passage. Dystrophic calcification occasionally occurs in degenerating and dead tissues, while
metastatic calcification is the result of an excess of
calcium salts in the circulating blood [1, 2].
The buccal soft tissues rarely contain lesions that
include calcifications. Phleboliths associated with vascular lesions are the most frequent [3, 4]. However, the
differential diagnosis includes sialolithiasis, traumatic
myositis ossificans, calcified acne lesions, neoplasms,
and calcified lymph nodes, including tuberculosis [5-9].
Plain x-rays show the typical appearance of the calcified bodies and may help to differentiate these entities.
Computed tomography (CT), magnetic resonance imaging (MRI), and ultrasonography are also useful for
differentiating these lesions.
We report a patient with a small mass that contained a calcified body in the anterior portion of the
masseter muscle. The mass was resected and evaluated
histologically, confirming the diagnosis of a phlebolith.
We also discuss the differential diagnosis of buccal soft
tissue masses with calcification and suggest that the
immunolocalization of CD31 at capillaries in the mass
may help to diagnose as a phlebolith.
A 17-year-old girl was referred to the Department
of Oral and Maxillofacial Surgery, National Hospital
Organization Shizuoka Medical Center, with a small,
painless, movable, hard nodule in the right buccal
submucosa. It was first noticed incidentally when the
patient touched her cheek 1 month earlier. The size
had not changed during the month. Her past and family histories were unremarkable.
There was no facial asymmetry, restriction of mouth
opening, swelling of the right cheek, or associated
lymph node enlargement. A soybean-sized, round nodule was palpable under the buccal skin and mucosa.
The skin and mucosa covering the lesion appeared
normal. The mass was located far from Stensen’s duct.
There was no history of trauma, dental problems, allergy, or other medical problems.
Intraoral radiographs revealed a radiopaque, milliary body in the soft tissue of the right cheek (Fig.
1). CT showed a round mass containing a small
radiopaque body in the anterior portion of the right
masseter muscle. The lesion was located between the
mandible and facial muscles. There was no enhancement within the mass (Fig. 2). T1-weighted MRI
revealed a well-circumscribed, round mass with a tail
in the anterior portion of the right masseter muscle.
The signal had a slightly greater intensity than the
surrounding muscle, but there was a low-intensity area
at the margin of the mass (Fig. 3A). T2-weighted MRI
Hisashi KATO, Department of Oral and Maxillofacial Surgery Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan
Tel: +81-463-93-1121 Fax: +81-463-95-7567 Email: hisashi@tokai-u.jp
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H. KATO et al. / A Phlebolith in the Anterior Portion of the Masseter Muscle
Fig. 1 Intraoral radiograph showing a spherical radiopaque body in the soft tissue of the right cheek
(black arrow).
Fig. 2 Enhanced axial CT image showing
a round mass containing a small radiopaque body in the anterior portion
of the right masseter muscle (white
arrow), with no enhancement within
the mass. The mass is located between
the mandible and facial muscles.
Fig. 3 MRI image showing a round mass with a tail. A, Axial T1-weighted MRI image
showing a mass in the anterior portion of the right masseter muscle (white arrow).
The signal intensity is slightly higher than in the muscle. There is a low-intensity area
at the margin of the mass. B, Axial T2-weighted MRI image showing a well-circumscribed, hyperintense mass in the anterior portion of the right masseter muscle (white
arrow). There are hypointense areas in the submarginal and central regions of the
lesion.
showed a hyperintense signal with a tail. Hypointense
areas were also seen in the submarginal and central
region of the lesion (Fig. 3B). Gadolinium-enhanced
T1-weighted MRI showed no enhancement in the
mass. Ultrasonography showed a 17 × 14 × 15 mm
mass with a smooth periphery in the cheek. The lesion
had low echogenicity and contained a calculus-like
body (Fig. 4). Ultrasound and color Doppler studies
suggested that it was not a vascular lesion. Threedimensional CT (3D- CT) angiography revealed no
vascular malformation associated with the facial artery
in the right cheek area. The rest of the clinical and
laboratory examination was within normal limits.
With the provisional diagnosis of a phlebolith,
sialolith in a minor salivary gland, or tumor in the
anterior portion of the right masseter muscle, the mass
was resected via an intraoral approach under general
anesthesia. A small round body was found in the right
buccal submucosa and removed.
The removed lesion was a 15 × 13 × 14 mm,
round, rubbery, bright reddish-brown mass, and with
a smooth surface (Fig. 5A). Macroscopically, the mass
was filled with bright brown, elastic soft tissue, which
had an onion-like appearance. A small calculus-like
body was embedded in the center of the lesion (Fig.
5B). Histopathologically, the mass was filled with lamellated red blood cells and an organized thrombus.
In addition, focal immunolocalization of CD31 was
identified in the capillaries in the phlebolith (Fig. 6).
The histological evaluation confirmed the diagnosis of
a phlebolith. There has been no recurrence in the 18
months since surgery.
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H. KATO et al. / A Phlebolith in the Anterior Portion of the Masseter Muscle
Fig. 4 Grayscale sonograms showing a
17 × 14 × 15 mm mass with a
smooth periphery in the cheek (white
arrow). The lesion has low echogenicity and contains a calculus-like
body.
A
B
Fig. 5 Macroscopic view of the gross specimen removed from the right buccal submucosa. A, The lesion measured 15 ×
13 × 14 mm and was round, rubbery, bright reddish-brown, and had a smooth surface. B, The bisected specimen
was filled with bright brown, elastic soft tissue, and had an onion-like appearance with a small calculus-like body
embedded in the center of the lesion.
A
B
Fig. 6 Photographs showing the pathological and immunohistochemical findings. A, The cut surface of the mass reveals a
concentric lamellar pattern. The outer lamina consists of thin fibrous connective tissues. The mass is filled with lamellated red blood cells and an organized thrombus. The calcification is associated with the thrombus in the center
of the lesion (hematoxylin-eosin, original magnification, ×8). B, Focal immunolocalization of CD31 is identified in
capillaries in the phlebolith (black arrow) (original magnification, ×40).
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H. KATO et al. / A Phlebolith in the Anterior Portion of the Masseter Muscle
DISCUSSION
When evaluating a buccal soft tissue mass with a
calculus-like body, phleboliths associated with vascular
lesions are the most frequent. However, the mass must
be differentiated from sialolithiasis, traumatic myositis
ossificans, calcified acne lesions, neoplasms, and calcified lymph nodes including tuberculosis [5-9].
Calcified acne lesions are easily ruled out based on
the clinical findings because they are superficial lesions
[3]. The appearance of calcified bodies on plain radiographs may help to differentiate other entities. A phlebolith is usually laminated, with a radiopaque center,
although the center is sometimes radiolucent; a small
phlebolith is uniformly radiopaque [3]. Moreover, there
are often multiple phleboliths when associated with
a hemangioma. By contrast, traumatic myositis ossificans, which is associated with trauma and occasionally
occurs in the masseter muscle, has a feathery pattern
along the muscle fibers or a striated linear morphology
[3]. The lymphadenopathy associated with tuberculosis
forms a cauliflower-shaped pattern in a chain [10].
In our case, the plain radiograph showed a round,
uniformly radiopaque lesion. Therefore, these two latter diseases could also be ruled out. A sialolith in the
buccal region can occur in the parotid duct and gland
or in a minor salivary gland. In our case, the calcified
body was not associated with the parotid gland, as it
was located far from Stensen’s duct. Although sialoliths
in the minor salivary glands are rare, they frequently
appear in the buccal mucosa. Perhaps masticatory
trauma to the buccal mucosa has some bearing on the
increased incidence of sialoliths in this area [6].
The pathogenesis of phleboliths is thought to involve
an organized thrombus produced when the peripheral
blood flow slows [3, 4]. The thrombus calcifies, forming the core of the phlebolith. Then, the fibrinous
component undergoes secondary calcification and
becomes attached. Repetition of this process causes
enlargement of the phlebolith [11]. Therefore, most
phleboliths are found along with vascular anomalies
such as a hemangioma. However, there are rare cases
that do not involve vascular anomalies. Although our
case was not associated with a vascular anomaly, the
mass was filled with lamellated red blood cells, and
the focal immunolocalization of CD31, which is found
on endothelial cells, was identified in the capillaries
[12]. The immunohistochemical finding of CD31 may
be evidence of a phlebolith.
Vascular anomalies usually include two separate
clinical and histopathological entities: hemangiomas
and vascular malformations [13]. Hemangiomas are
the most common benign soft tissue tumors of childhood [13]. In the maxillofacial area, intramuscular
hemangiomas most frequently occur in the masseter
muscle [14]. Approximately 40% of venous malformations, which are the most common vascular malformation, are located in the head and neck region [13,
15, 16]. In addition, there occasionally is masticatory
trauma to the buccal mucosa, leading to thrombus formation [15]. Therefore, phleboliths are most frequently
found in the buccal region. Although there was no
history of trauma in our case, there might have been
unidentified masticatory trauma to the buccal mucosa.
Diagnostic imaging modalities such as CT, MRI,
and ultrasonography have significantly increased the
accuracy of the preoperative diagnosis of patients with
such lesions [11]. Vascular lesions are characteristically much brighter on T2-weighted images than T1weighted images due to the increased free water present within stagnant blood in the vessels. Ultrasound
and color Doppler studies can also suggest a vascular
lesion [16]. In our case, the lesion was characteristically
much brighter on T2-weighted MRI images and there
was no enhancement or blood flow within the mass. In
the preoperative assessment, CT, MRI, and ultrasonography accurately showed that the mass did not involve
vascular anomalies and contained a calculus-like body.
When evaluating a buccal soft-tissue mass with
a calculus-like body, the lesion should initially be
considered a phlebolith in patient who are in the
first or second decade of life. In addition, a detailed
interview of the history of the illness, such as injury
and masticatory trauma to the buccal mucosa, may
help to differentiate several entities. Plain x-rays may
also help with the diagnosis because of the typical
appearance of the calcified bodies and CT, MRI, and
ultrasonography are more useful for making an accurate diagnosis. Moreover, the immunolocalization of
CD31 to capillaries in the mass may help to diagnose
as a phlebolith when the mass does not accompany a
vascular anomaly.
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