Clinicopathologic characteristics of Nocardia brain abscesses: Necrotic and non-necrotic foci of various stages

Nocardia brain abscesses are rare bacterial infections associated with a high mortality rate, and their preoperative diagnosis can be difficult for various reasons including a nonspecific clinical presentation. While late-stage nocardial brain abscesses may be radiologically characteristic, early-stage lesions are nonspecific and indistinguishable from another inflammatory/infectious process and other mimics. Despite the paucity of previous histopathological descriptions, histopathological examination is critical for the identification of the pathogen, lesion stage(s), and possible coexisting pathology. In this study, we examined the clinical, radiological and histopathological features of 10 patients with brain nocardiosis. Microscopic findings were analysed in correlation with clinical and radiological features in 9 patients, which revealed that brain nocardiosis was characterized by numerous necrotic and non-necrotic foci of various stages (I-IV) along with Nocardia identification, as well as the leptomeningeal involvement in most cases, and co-infection of brain nocardiosis with toxoplasmosis in 2 patients. The imaging features were characteristic with a multilobulated/bilobed ring-enhancing appearance in 8 patients including 2 patients with multiple lobulated and non-lobulated lesions and 1 patient showing the progression from a non-lobulated to lobulated lesion. These findings suggest that nocardial brain abscesses particularly at late-stages share common characteristics. Nevertheless, given the complex pathologic features, including possible co-infection by other pathogens, nocardial brain abscesses remain a therapeutic challenge.

Hypertrophic Interstitial Neuropathy of the Trigeminal Nerve: Case Report and Literature Review

BACKGROUND AND IMPORTANCE

Hypertrophic interstitial neuropathy (HIN) is an uncommon, non-neoplastic lesion typically affecting peripheral nerves. Cranial nerve (CN) involvement is exceedingly rare. We present a case of isolated trigeminal nerve HIN manifesting with V3 distribution neuralgia.

CLINICAL PRESENTATION

A 50-yr-old male presented with left sided trigeminal neuralgia refractory to medical management. The patient underwent retromastoid craniectomy for possible microvascular decompression. Intra-operatively, the trigeminal nerve appeared to be focally enlarged with a sausage-like configuration. We selectively resected 1 fascicle which was predominantly involved. Histopathological examination revealed onion bulb formations composed of Schwann cells around centrally placed axons. A diagnosis of HIN was made. Postoperatively, the patient experienced complete resolution of symptoms.

CONCLUSION

This is the third case of isolated trigeminal nerve HIN in the literature. We performed a selective resection in a patient presenting with trigeminal neuralgia, resulting in complete resolution of symptoms. It is reported here with intraoperative microscope images, along with a review and analysis of this topic as it related to CN.

Incidental multifocal calcifying pseudoneoplasm of the neuraxis: case report and literature review

Calcifying pseudoneoplasm of the neuraxis (CAPNON) is thought to be a rare tumefactive lesion with unknown pathogenesis. Its prevalence is questionable with few previously reported cases of incidental CAPNON, and likely underdiagnosis. We report a unique case of incidental multifocal CAPNON. A 64-year-old female was admitted with loss of consciousness due to a ruptured right middle cerebral artery aneurysm with subarachnoid and intraventricular hemorrhage. She has a craniotomy and clipping. At time of operation, numerous small dural-based nodules were found, and one was excised for biopsy and was diagnosed as CAPNON. Retrospective review of her CT images identified nodules that were all ipsilateral to the ruptured aneurysm. A literature review revealed that incidental and/or multifocal CAPNONs are rare but likely underreported. Our case suggests a reactive process in the pathogenesis of CAPNON.

Aneurysmal Bone Cyst of the Temporal Bone Presenting with Headache and Partial Facial Palsy

Background Aneurysmal bone cysts (ABCs) are benign bony lesions that rarely affect the skull base. Very few cases of temporal bone ABCs have been reported. We describe the first case of a temporal bone ABC that was thought to be consistent with a meningioma based on preoperative magnetic resonance imaging (MRI) findings. Clinical Presentation An otherwise healthy 23-year-old woman presented with a pulsatile noise in her left ear and a 4-week history of throbbing headache with nausea. There was no associated emesis, visual or auditory changes, or other neurologic features. Neurologic examination revealed a left lower motor neuron facial paresis. Computed tomography and MRI studies demonstrated a large lesion in the left middle cranial fossa skull base with erosion of the petrous temporal bone. Based on the presence of a "dural tail" on preoperative contrast-enhanced T1-weighted imaging, the lesion was interpreted to likely be consistent with a meningioma. An orbitozygomatic approach was utilized for surgical excision. Histopathologic evaluation was consistent with an ABC. Conclusion Postoperatively the patient had improvement in the lower motor neuron facial paresis. It is important to consider ABC in the differential diagnosis of intracranial lesions accompanied by the dural tail sign on MRI.