Cerebral actinomycosis : unusual clinical and radiological findings of an abscess

An invasive and diffuse cranial actinomycosis with a dura-based mass mimicking a brain tumor: illustrative case

BACKGROUND

Actinomycosis is a chronic suppurative infection caused by non-spore-forming, anaerobic, and filamentous gram-positive bacteria. Primary central nervous system involvement is rare, with no specific clinical features, causing a clinical diagnostic dilemma. Imaging can help in localizing and characterizing the lesion; however, a definitive diagnosis relies on culture and/or histopathology.

OBSERVATIONS

The authors describe a 29-year-old male farmer with a rare case of invasive and diffuse cranial actinomycosis with a dura-based mass mimicking a brain tumor. Brain magnetic resonance imaging showed a moderately enhanced right frontoparietal infiltrative dura-based mass with marked thickening of the skull and multiple scalp actinomycotic abscesses. He underwent microsurgical excision of the mass, orbital decompression, and debridement of the scalp abscess. Histopathology confirmed actinomycosis, and his postoperative course was uneventful.

LESSONS

Invasive and diffuse cranial actinomycosis with a dura-based actinomycetoma is a rare presentation that poses a diagnostic challenge due to its nonspecific manifestations. Imaging is helpful in localizing and characterizing the lesion; however, histopathology remains the gold standard for diagnosing actinomycosis. A high index of suspicion is also warranted in patients with predisposing factors to promote an early diagnosis and the initiation of appropriate treatments to improve functional recovery and limit residual deficits. https://thejns.org/doi/10.3171/CASE24210.

Actinomyces causing a brain abscess

Actinomycosis is an uncommon, chronic granulomatous disease caused by the filamentous, gram-positive bacterium Actinomyces israelii. It causes indolent, painful wound infections commonly presenting with oral-cervicofacial manifestations, but other infections of the chest wall and gastrointestinal and genital tract are also seen. A high level of suspicion is required for diagnosis, as it may be missed or mistaken for malignancy. Severe cases may involve the central nervous system and require surgical intervention. We present a case report of actinomycosis causing a brain abscess.

A Case of CNS Actinomycosis: Rarer than Rare!

We report a case of cerebral actinomycosis in a 62-year-old male who presented with right-sided weakness and focal convulsions. MRI scan showed a solid intra axial space occupying lesion in the left frontal lobe. Left parietal craniotomy with intra-operative USG guided aspiration and excision of the mass (containing necrotic material) was done. Actinomyces israelii was isolated from the aspirated material. Patient received ceftriaxone and clindamycin for 12 weeks. Physiotherapy and anti-epileptic drugs were continued. On subsequent follow-up visits, his power improved to 5/5 in lower limb, 4/5 in proximal upper limb, 2/5 in distal upper limb. Actinomycosis can cause diverse clinical manifestations, and therefore clinical suspicion is key to diagnosis. Early diagnosis and treatment can lead to good treatment outcomes.

Skull Imaging-Radiographs and CT revisited

Although rare, skull vault lesions include a vast array of pathology encompassing infection, benign, and malignant bone tumors. Given the large range of potential diagnoses, it is crucial to identify imaging features to differentiate one from another, ensuring early diagnosis. Radiographs are still valuable in modern radiology but have largely been superseded by computed tomography (CT) due to its high spatial resolution. Both are especially important in developing countries where access to magnetic resonance imaging (MRI) may be limited.There are currently several publications outlining imaging appearances of skull vault lesions. However, the majority of literature is dated, with the last dedicated textbook published in 1980 (Principles of X-ray diagnosis of the skull). Despite overlapping features, a few lesions have "aunt minnie," type classical characteristics, which we will highlight. Most vault lesions also appear as a spectrum depending on location and the exact stage of the disease. A small subset within each disease entity also has atypical features not widely discussed in the current literature. In this pictorial review, we hope to focus on radiographic and CT imaging appearances to help differentiate between various skull vault lesions.

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

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.

Intracerebral Abscess Caused by Actinomyces israelii

We describe a case of 49-years old female with a medical history of penicillin allergy, who suffered from brain infection caused by Actinomyces israelii. Therefore, the available therapy was metronidazole, ceftriaxone, and chloramphenicol. Due to a deterioration of the general and neurological condition of the patient, it was decided to perform a scratch skin test on penicillin, which was negative. After that, penicillin was administrated parenterally. The patient showed no hypersensitive reaction. Improvement was achieved. The patient underwent three subsequent surgeries due to primary and recurrent brain abscesses. There was a distinct improvement in her clinical status. Two months after the second re-surgery, the control computed tomography showed complete regression of the abscess.

Brain abscess caused by an Actinomycess israelii is very resistant to medication. However, surgical evacuation significantly accelerates the healing process. A good medication therapy is crucial and in most cases the drug of choice is penicillin. We emphasize the importance of a combined approach for treating this unusual brain infection.

Actinomycotic brain abscess

Actinomycosis is caused by Gram-positive filamentous anaerobic organisms of genus Actinomyces, which are commensals of mucosal membranes of the oropharyngeal cavity, and gastrointestinal and genitourinary tracts. Central nervous system involvement is rare and may present as cerebral abscess, meningitis, meningoencephalitis, subdural empyema or epidural abscess. The radiological appearances of actinomycotic brain abscesses are not well recognized. Here, we present the characteristic imaging features of an actinomycotic brain abscess.

Actinomycosis Mimicking Tolosa-Hunt Syndrome in a 6-Year-Old Boy: Case Report

Tolosa-Hunt syndrome is an idiopathic inflammatory process of the cavernous sinus or orbit manifesting as painful ophthalmoplegia. In this report, we detail the case of a 6-year-old boy who presented with several weeks of unilateral headache and diplopia. He was found to have an infiltrative process involving the bilateral cavernous sinuses and pituitary gland on MRI. Given a progressing infiltrative central nervous system process on repeat MRI and the development of cerebral salt wasting, a biopsy was performed revealing actinomycosis. To our knowledge, this is the first reported case of actinomycosis masquerading as Tolosa-Hunt syndrome in a child.

A Case of Disseminated Infection due to Actinomyces meyeri Involving Lung and Brain

Actinomyces meyeri is rarely isolated in cases of actinomycosis. The identification of A. meyeri had historically been difficult and unreliable. With the recent development of 16S ribosomal RNA (16S rRNA) sequencing, Actinomyces species such as A. meyeri can be isolated much more reliably. A. meyeri often causes disseminated disease, which can be secondary to frequent pulmonary infections. A penicillin-based regimen is the mainstay of A. meyeri treatment, with a prolonged course usually required. Here, we report a case of pulmonary actinomycosis with brain abscess caused by A. meyeri that was initially thought to represent lung cancer with brain metastasis.