99mTc-UBI 29-41 bone SPECT/CT scan in craniofacial Actinomyces israelii: Misdiagnosis of cranial bone tumor - A case report

Abstract

Background: Actinomycosis is a rare infection, frequently misdiagnosed as a neoplasia. This chronic and granulomatous disease is caused by Actinomyces israelii species. Cervicofacial actinomycosis occurs in 60% of cases and the diagnosis is commonly made by histopathology study.

Case description: We report a case of fronto-orbital osteomyelitis initially misdiagnosed as a cranial bone meningioma, but later proved to be a case of actinomycosis. ^99mTechnetium (^99mTc) three-phase bone single-photon emission computed tomography/computed tomography (SPECT/CT) and ^99mTc-ubiquicidin (UBI) 29-41 bone SPECT/CT scans were performed to corroborate the control of the infection.

Conclusion: Craniofacial actinomycosis is the most common presentation of actinomycosis. However, it continues to be a rare and difficult disease to diagnose and is often confused with a neoplastic process. The ^99mTc-UBI 29-41 bone SPECT/CT scan could be an auxiliary noninvasive diagnostic alternative and a follow-up method for these patients.

Keywords: Actinomyces; Craniofacial; Osteomyelitis.

Figure 1:

(a) Presurgical images, significant bilateral fronto-orbital defect, predominantly right side. (b and c) control 3 years after surgery, significant remission of bone deformity.

Figure 2:

(a-c) (Upper quadrants) Presurgical gadolinium-enhanced T1-weighted magnetic resonance imaging showing heterogeneous enhancement mass in the bilateral fronto-orbital region predominantly on the right side, we can see a hypodensity in relation to methyl methacrylate. (d-f) (Lower quadrants) Computed tomography scan control 6 months after the medical treatment with resolution of the deformity.

Figure 3:

Hematoxylin and eosin staining. Basophilic structure, granular, and peripheral-pseudopalisading, hemorrhagic background, and peripheral lymphocytic and polymorphonuclear infiltrate.

Figure 4:

(a and b) 3D computed tomography (CT) scan showing silicone implants in the chin and zygomatic bone, a supraorbital methyl methacrylate bar and plates in the bilateral parietal region (upper quadrants). (c and d) (Lower quadrants): ^99mtechnetiumUbiquicidin (29–41)/three-phase bone single-photon emission computed tomography/CT scan control 3 years after the last surgical intervention showing diffuse uptake of the radiotracer, suggestive of an inflammatory process, an active infectious process is ruled out.