Discussion:
More than half of the reported cases of actinomycosis have a cervicofacial localisation. However, nasal and paranasal sinus involvement has rarely been described (3,4,13,5–12) Only one case of middle turbinate actinomycosis was reported in the English literature (5).
Although the term actinomyces has a Greek origin meaning “ray fungus”, actinomycosis is a chronic bacterial granulomatous infection caused by gram-positive, anaerobic to microaerophilic bacteria that are not acid fast.
Actinomyces israelii is the most common human pathogen of actinomycosis that inhabits oral and buccal cavities and is considered to be endogenous commensal organism.(14)Hence, the loss of mucosal integrity by direct trauma, tooth extraction, root canal therapy, periodontal or periapical lesions is incriminated in the onset of the disease(15). However, our patient did not have any dental history. Her buccal examination did not reveal any abnormalities.
Patients usually present with non-specific unilateral nasal symptoms consistent with chronic sinusitis such as purulent nasal discharge, nasal obstruction, foul odour, sinusalgia (16)(13)
Paranasal sinuses computed tomography imaging does not permit a specific diagnosis. It shows opacities in the paranasal sinus, focal calcified lesions and/or focal areas of bone destruction. However, it allows more accurate definition of the dimensions and extension of the infection.(1) Given the imaging findings, many other differentials may be evoked as it has been mentioned in our case report; nasal and paranasal actinomycosis has to be differentiated from nocardiosis, fungal sinusitis, and neoplasms.(12)
Positive bacterial culture confirms the diagnosis. However its low rate of isolation makes it difficult. We did not carry out bacterial testing for our patient.
Histologic exam reveals the characteristic sulfur granules in 30% of cases. They are described as tiny, yellow-white, lobulated, grainy microcolonies with club-shaped filaments, measuring 1-5 μm in diameter and radiating in a rosette pattern, surrounded by inflammatory cells. Our patient histologic findings were consistent with these constatations (figure 3). However, sulfur granules are not pathognomonic since they have also been described in nocardiosis and botryomycosis. (5,12)
As for the therapeutic recommendations, both surgical and medical treatments should be combined. In fact, vascular supply decreases in actynomycosis-infected tissues making difficult the penetration of antibiotics to the lesion. Therefore, the lesion should be surgically removed and the surrounding tissues thoroughly debrided.(14,17) Then, surgery should be followed by a long-term-penicillin therapy; Penicillin G (50–75 mg/kg/day intravenously in four daily divided doses) for 4 to 6 weeks followed by peroral penicillin V (30–60 mg/kg/day administered in four divided doses) for 2 to 12 months(1) .
If the patient is known allergic to penicillin, tetracycline, clyndamycine, cephalosporin or erythromycin may be prescribed(5,14)
Fluoroquinolones, aztreonam, fosfomycin, and other aminoglycosides are known to have poor activity against Actinomyces species.(2,18)
However, no consensus has been reached on the antibiotic therapy duration. It has been established that patients with cervicofacial actinomycosis have a favourable prognosis since some occasional cures with aggressive surgery alone has been reported in the preantibiotic era (19).
The duration of the antibiotic therapy should be individualized based on the site of the infection, the clinical and the radiologic response to the treatment and its severity. Short courses-regimen consisting of 2 to 6 weeks of oral antibiotic therapy (+/- intravenous )associated with surgical debridement have been reported to be curative in recent studies.(19) A thorough and prolonged follow-up is required in order to watch for recurrence which might happen after several years (13)
As for our patient, we opted for an endoscopic surgical treatment followed by a four-week oral antibiotherapy (80 mg/kg/day of oral amoxicillin-clavulanic acid). No signs of relapse were detected during her six-month-follow-up care.