Subacute Actinomycotic Osteomyelitis of the Mandible – An Underreported Disease?

Abstract

Background/Aim: Cervicofacial actinomycosis is a rare entity. The manifestation of this disease in the context of osteomyelitis in the mandible is even rarer.

Case Report: This case report describes a 70-year-old female with a painful swelling in the left mandible. The swelling was initially noticed four weeks ago. Furthermore, the patient reported problems with medications concerning her type II diabetes mellitus. Due to multiple decayed teeth, the patient had multiple teeth extracted in recent years, including teeth 36-38 in the left mandible. Orthopantogram (OPG) and computed tomography (CT) scan showed an unspecific osteolysis in the left mandible. An incisional biopsy was performed revealing subacute necrotizing osteomyelitis of the mandible due to actinomyces. Furthermore, the patient was treated with open debridement, curettage, and decortication as well as long term antibiotics (amoxicillin + clavulanic acid) for 6 weeks. In addition, type II diabetes mellitus could be controlled with various medications (Metformin, Dapagliflozin). Clinical follow-up revealed no evidence of recurrence.

Conclusion: Even though actinomycosis is rare, it should be included in the differential diagnosis of unspecific osteomyelitis of the jaw. Antibiotics and surgical decortication are the crucial therapy pillars when treating actinomycotic osteomyelitis in the mandible.

Osteomyelitis of the jaw is usually caused by an infection with bacteria from the oral cavity (1). Depending on the clinical course, osteomyelitis can lead to osteonecrosis in the affected jaw. Osteomyelitis of the jaw bones differs significantly from osteomyelitis of the rest of the skeletal system due to the special conditions and microbiome of the oral cavity. According to the Zurich classification, there are three different forms of osteomyelitis: Acute and secondary chronic, primary chronic and chronic recurrent multifocal osteomyelitis (2). In particular, the acute form of osteomyelitis typically affects the mandible. Acute osteomyelitis is often caused by postoperative and/or posttraumatic colonization of the bone with staphylococci bacteria of the oral cavity (3). In rare cases, acute osteomyelitis is triggered by other bacteria or fungal infections (4). Endogenous osteomyelitis in the sense of hematogenous bacterial spread is rare. A rare cause of osteomyelitis is infection with actinomycetes. Actinomycosis is often caused by mixed infection with bacterial and actinomycetes (mainly A. israelii and A. gerencseria), which occur locally as saprophytes in the oral cavity (5). Actinomycotic infection primarily affects soft tissues. This bacterium often shows a subacute to chronic clinical course (intermittent diffuse symptoms) and is rarely the cause for osteomyelitis in the jaw (6). The diagnosis of actinomycotic osteomyelitis is particularly challenging. The aim of this article was to demonstrate the diagnostical course of this rare entity and to demonstrate the successful treatment of subacute actinomycotic osteomyelitis in the oral cavity in the context of type II diabetes mellitus.

Case Report

A 70-year-old female with type II diabetes mellitus presented with a painful swelling in the left mandible. The swelling was initially noticed four weeks ago and showed a consistent progression in size. Furthermore, the patient reported problems with the medications concerning her diabetes type II. At the time of the first presentation, an HbA1c value of 8.4% was determined as well as unstable blood sugar levels. Due to multiple decayed teeth, the patient had multiple teeth extracted in recent years, including teeth 36-38 in the left mandible. However, the teeth were extracted four years ago. In the meantime, the patient did not have any symptoms regarding the mandible.

The clinical examination revealed a peri- to submandibular swelling on the left. Intraorally, there was a mucosal swelling in region 036-038. Due to the pronounced symptoms, an orthopantogram (OPG) was performed showing an unspecific osteolysis in the left mandible (Figure 1A). Furthermore, a computed tomography (CT) scan of the mandible was performed confirming the unspecific osteolysis of the mandible (Figure 1B). She was subjected to surgical therapy consisted of an incisional biopsy of the mucosal swelling as well as the osteolysis of the mandible. Written informed consent was obtained from the patient.

Figure 1. Radiological and histopathological findings. A) Preoperative orthopantogram showing an unspecific osteolysis in the left mandible region 36-38. B) Preoperative computed tomography-scan in a coronal view showing an unspecific osteolysis of the mandible region 036-038. C) Hematoxylin and eosin (H&E, 400×); Within the marrow spaces of mostly avital cancellous bone, abundant neutrophilic granulocytes and the so-called actinomycotic granules (AMGs), composed of thin basophilic radiating filaments in the periphery and a denser eosinophilic core zone, are recognized. D) H&E 400×; Avital cancellous bone with AMGs, composed of thin basophilic radiating filaments as well as abundant neutrophilic granulocytes.

A granulation polyp was found in the mucosa. The histopathological findings revealed the rare case of acute necrotizing osteomyelitis of the mandible due to actinomyces colonization (Figure 1C and D). In addition to that the patient received surgical treatment with open debridement, curettage, and saucerization. Several areas of the left mandible were debrided through decortication. The surgical therapy was supplemented with perioperative antibiotics (amoxicillin + clavulanic acid). Antibiotics were continued for 6 weeks. In addition, type II diabetes mellitus could be controlled with various medications towards a stable blood sugar level (Metformin, Dapagliflozin). The clinical and radiological follow-up revealed no evidence of a recurrence and/or recurring symptoms of osteomyelitis as well as stable blood sugar levels.

Discussion

Actinomyces occur in different anatomical regions. However, its localization in the cervicofacial region is the most common (6). The peak incidence of this disease is in young adults (7). The cervicofacial manifestation of actinomycosis is rare, especially in Western countries (5). Risk factors for this disease are immunosuppression, systemic diseases such as type II diabetes mellitus, alcoholism, and malnutrition (5,6).

Actinomycosis often manifests itself clinically as infection in the oral cavity with hard knots, fistulas, and abscesses. Canaliculitis of the lacrimal ducts has also been described in the context of actinomycosis (8). However, this disease is often asymptomatic and can hide under the symptoms of the so called "lumpy jaw" (6).

A manifestation of actinomycosis as osteomyelitis is possible, but rarely described. Depending on the species, actinomycetes without adequate therapy tend to fulminant destructive processes with spread to the surrounding structures. Since the facial region has many anatomical peculiarities, a cervicofacial manifestation is particularly dangerous. One of the greatest dangers of this infection in the context of osteomyelitis of the jaw is extensive osteonecrosis. Since this disease usually progresses chronically without antibiotic treatment and/or surgical intervention, rapid diagnosis and initiation of therapy are crucial (5).

However, the diagnosis is challenging. The histopathological processing of the affected tissue parts with the detection of “drusen” is particularly suitable for this. The “drusen” appear microscopically as accumulations of actinomycete conglomerates including perifocal granulocyte accumulation (9). The radially protruding, branched actinomycetes are characteristic. Furthermore, there is the possibility of determining the species by means of PCR diagnostics as well as the cultural detection of the pathogen.

In the context of radiological imaging, fuzzy hypodense osteolysis in the context of osteomyelitis can be detected in OPG as well as CT scan. A clear radiological finding for osteomyelitis associated with actinomycetes does not yet exist.

The treatment of choice for cervicofacial actinomycotic osteomyelitis in the mandible consists of two therapy pillars - surgical debridement or decortication with possible subsequent defect coverage and long-term treatment with antibiotics for at least 4-6 weeks (especially penicillin and/or amoxicillin/ clavulanic acid, in case of penicillin allergy: clindamycin) (6,7). In the context of radical jaw resections in jaw parts that are not preservable, surgical replacement with a reconstruction plate needs to be considered. In a two-stage approach, a definitive reconstruction of the jawbone can be achieved, for example with a pelvic bone or fibula transplant, after the infection focus has been successfully removed (10). In addition, this disease must be classified individually for each patient in the context of his/her comorbidities. Attention should also be paid to the adequate therapy of systemic diseases such as type II diabetes mellitus. Despite optimal surgical and anti-infective therapy, recurrences are common in osteomyelitis and especially in cervicofacial actinomycoses (11,12). From this, a long-term clinical follow-up can be implemented to diagnose early recurrences and to quickly initiate the mentioned therapy steps.

Conclusion

Cervicofacial actinomycosis is a rare entity. The manifestation of this disease in the context of osteomyelitis of the mandible is even rarer. The present case illustrates a direct connection between a relevant systemic disease such as diabetes mellitus type II and osteomyelitis of the mandible associated with actinomycetes. In addition, this case report emphasizes the difficulties in finding a diagnosis and the two pillars of therapy (long-term antibiotic treatment and surgical intervention) of this disease in the area of the mandible.

Conflicts of Interest

The Authors have no relevant financial or non-financial interests to disclose.

Authors’ Contributions

KOH, FB, and FD treated the patient and revised the article. FD and FB searched the scientific literature. AZK provided histopathological findings. FD and FB wrote the article. All Authors gave final approval for publication.

Funding

The Authors declare that no funds, grants, or other support were received during the preparation of this manuscript.