Mandibular Actinomyces Infection Mimicking a Malignancy: Case Report
Gülay BULUT1, Yasemin BAYRAM2, Mehmet Deniz BULUT3, Mehmet Fatih GARÇA4, İrfan BAYRAM1
1Departments of Pathology, Yüzüncü Yıl University, Faculty of Medicine, VAN, TURKEY
2Departments of Microbiology, Yüzüncü Yıl University, Faculty of Medicine, VAN, TURKEY
3Departments of Radiology, Yüzüncü Yıl University, Faculty of Medicine, VAN, TURKEY
4Departments of Otorhinolaryngology, Yüzüncü Yıl University, Faculty of Medicine, VAN, TURKEY
Keywords: Cervicofacial actinomycosis, Pathology, Mandible
Actinomycosis is a rare, chronic, suppurative and granulomatous
disease caused by Actinomyces israelii, which is a filamentous,
anaerobic, gram-positive, saprophytic organism in the oral
cavity. Diagnosis of actinomycosis depends on positive culture
or identification of Actinomyces colonies and sulfur granules in
histological specimens. In our case, a mass had been growing in
the mandible for eight months. The mass appeared to be malignant,
both clinically and radiologically. A histopathological examination
of the mandible revealed actinomycosis. It should be noted that
actinomycosis can mimic a malignancy, and for differential
diagnosis, bone biopsy or fine-needle aspiration should be performed
The microorganisms classified as Actinomyces are common
inhabitants of the oral cavity and the human pharynx
region. Actinomycotic infection in chronic inflammation
has specific effects on primary soft tissues, rarely affecting
. After the destruction of the oral mucosa, the
anaerobic, filamentous, gram-positive, saprophytic and
slow-growing bacterium Actinomyces israelii develops2
It widely affects the neck, mandible, tonsils, hard palate,
paranasal sinus, lacrimal gland, parotid gland, and the orbit
in the cervicofacial area3,4
. Alveolar bone and mandibular
corpus actinomycosis is rare. The pathogenic mechanism
underlying actinomycotic infiltration is unknown5
The first incidence of actinomycosis in humans was
defined as a fungal infection by Von Langenbeck in 1845.
In 1891, Israel and Ponfick described the anaerobic nature
of Actinomyces. In 1960, Waksman demonstrated that
Actinomyces were gram-positive bacteria5.
The cervical region, and particularly the submandibular
area, is the main region that is affected in actinomycosis.
Diagnosis is based on fine-needle aspiration cytology and
biopsy. Computed tomography and magnetic resonance
imaging can be useful for determining the size of the lesion.
It is known that this disease has a tendency to resemble
carcinoma and tuberculosis5.
The case was a 16-year-old male patient who described a
growing, painless mass in the left cheek for eight months.
There was no history of trauma, although scar formation was
noted on the skin. With deep palpation, there was no pain
or heat associated with the palpation. A lack of teeth was
observed during the oral cavity examination. Hematological
examination revealed that the white blood cell count was
at the high end of the normal range (11.1 x 109/L; normal
range, 4-11 x 109/L). Tomography revealed significant
cortical irregularity at the level of the left mandibular corpus condyle and the mandibular angulus as well as at
the medullary area. An expansile mass of approximately
63x23x45 mm in size causing sclerosis with the formation
of new bone around the bone, including multilocular cystic
spaces, was observed. An evaluation of the tomography
findings indicated ameloblastoma (Figure 1A,B
). The patient
was then referred to our center. The patient was operated on according to the results of tomography. No positive cultures
were obtained from the wound site after the operation. The
materials removed for macroscopic examination were a
tissue sample 10x2.5x2.5 cm in size with a hard consistency
compatible with mandibular bone and a mass 6.5x3x2.5 cm
in size with two teeth. Severe active chronic inflammation,
abscess formation, and osteomyelitis were observed on
histopathological examination (Figure 2
). Sulfur granules
were observed via histochemical staining, and filamentous
bacilli that stained positive with Gomori’s methenamine
silver stain (GMS) (Figure 3
) and Periodic acid–Schiff
stain (PAS) were also observed. The patient was diagnosed
with an Actinomyces infection. After 2 years, the patient
remained well and did not show signs of infectious relapse.
Click Here to Zoom
|Figure 1: Axial bone window CT (A) and coronal CT (B) scans
demonstrate an expansive, lytic-sclerotic bone lesion with welldefined
margins affecting the left angle/ramus of the mandible.
Click Here to Zoom
|Figure 2: Identification of osteomyelitis and the location of the
abscess in the mandible (HE, x40).
Primary actinomycotic osteomyelitis is rare, corresponding
to approximately 12% of osteomyelitis cases6
. It affects
the cervicofacial region, typically the body of the mandible, followed by the region of the chin, branch, and angle of
the mandible; however, it rarely affects the upper jaw or
temporomandibular joint. Its prevalence in the mandible in
relation to the maxilla is 4:1, as reported in the present case1
Actinomycosis infections usually involve the cervicofacial,
thoracic, and abdominopelvic regions as well as the cranionervous
system, and no person-to-person transmission has
been documented. Actinomycotic osteomyelitis mainly
occurs due to adjacent tissue infection, but it can also be
observed in some fractures or in hematogenous spread.
Cutaneous sinus tracts usually develop6.
Radiologically, it is difficult to differentiate mandibular
osteomyelitis from other neoplasias. Therefore, in such
cases, bone lesion biopsy is important for determining the
nature of the lesion.
Ultrasound is the primary preferred imaging technique
that is used routinely for the neck region due to lack of side
effects and rapid implementation. During ultrasound, fine
needle aspiration cytology can be performed to achieve a
pathological diagnosis. Computed tomography is more
effective for identifying abscesses and surrounding anatomic
structures; however, it may not fully reveal specific masses
in soft tissue. Branchial cleft cyst, lymph node metastasis,
inflammatory lymphadenopathy, and vascular tumors are
the differential radiological diagnoses7.
Clinical diagnosis is difficult due to non-specific findings.
Differential diagnoses include many diseases, from tumors
to chronic diseases (carcinoma, tuberculosis, and others).
Cases are diagnosed based on the presence of bacteria
with a positive culture and biopsy. Pathological diagnosis
is simpler and less invasive using fine-needle aspiration
cytology. Yellow sulfur granules are typically observed in the
purulent material, which may be helpful in diagnosis. The
drained material can be cultured; however, less than 50%
of the cultures are positive. Through the use of microscopy,
colonies can be observed as filamentous bacilli with
granular centers and a radial distribution7. We diagnosed
the mandibular mass as mandibular osteomyelitis caused
by actinomycosis by observing positive filamentous bacilli
with GMS, PAS, and Gram stain. Histochemical analysis of
cervicofacial lesions can be used to determine the possibility
of actinomycosis infection.
Bartkowski et al. reported 15 cases with actinomycotic
osteomyelitis in the mandible. While nine of those
cases were primary actinomycotic inflammation of the
mandible, mandibular fracture or mandibular resection
was observed in six of them. The authors reported that they obtained the diagnosis on the basis of bacteriological
and histopathological tests8. Additionally, in our case,
oral hygiene was poor, and there were healed wounds and
fistula scars on the skin. Our case differed from the other
published cases because the lesion in our case had a mass
image, and similar cases were not found in the literature.
We used histopathology and histochemistry to achieve a
diagnosis, and our outcome emphasized the importance of
histopathology for diagnosing such lesions.
As a result, it is suggested that actinomycosis infections can
mimic malignancy because in our case, the mass occurring
in the mandible was clinically and radiologically evaluated
primarily as a tumoral formation in the preoperative
period. Ultrasound-guided fine-needle aspiration or
biopsy will be very valuable for preoperative diagnosis of
cervicofacial masses. Actinomycosis should be considered
in patients with cervicofacial lesions because it may mimic
malignancy. The removal of the infected bone, careful
debridement of dental remains, and long-term intravenous
and oral antibiotic therapy will be effective in the treatment
of mandibular osteomyelitis caused by actinomyces.
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