Cerebral actinomycosis : unusual clinical and radiological findings of an abscess

Abstract

We report a case of cerebral actinomycosis in a 69-year-old immunocompetent woman. The patient showed a progressive worsened mental status for one week. MRI examination showed an increased size of multiple enhancing nodular lesions associated with mild perilesional edema. We performed an open biopsy for the right frontal enhancing lesion. The intraoperative finding showed a yellowish friable lesion that was not demarcated with normal tissue. Pathologically, an actinomycotic lesion with sulfur granules and inflammatory cells was diagnosed. We report an unusual case of diffuse involvement of cerebral actinomycosis. The presence of the uncapsulated friable lesion that consisted mainly of foamy macrophages and lymphocytes could explain the unusual radiological features.

Keywords: Actinomycosis; Cerebral abscess; MR imaging.

Fig. 1

Radiological findings (pretreatment). These lesions are hypointense as seen on T1-weighted images and hyperintense as seen on T2 weighted images with mild perilesional edema (A-D). The lesions show ring or nodular enhancement and there is no diffusion restriction (E, F and G). 1H-MR spectroscopy shows an increased choline level, decreased N-acetylaspartate level and elevated lactate and lipid peaks (H).

Fig. 2

Intraoperative and pathological findings. The intraoperative finding is a yellowish friable uncapsulated lesion that is not well demarcated with normal tissue and there was no necrotic pus (A). Pathologically, the enhancing lesion is mostly composed of foamy macrophages that were immunopositive for CD68 (B and C). Sulfur granules are present, a typical finding associated with actinomycosis (D).

Fig. 3

Radiological findings (posttreatment). Multifocal encephalomalacias in periventricular white matter are shown (A and B) with disappearance of enhancing lesions (C and D).