Brain Tumor Res Treat.  2025 Jan;13(1):34-38. 10.14791/btrt.2025.0002.

Differential Diagnosis of a Well-Enhancing Intracisternal Lesion in a Breast Cancer Patient

• Song HC
• Gwak HS

• KMID: 2565048
• DOI: http://doi.org/10.14791/btrt.2025.0002

Abstract

This case introduces the differential diagnosis of a well-enhancing lesion in the prepontine cistern of a 55-year-old female patient who was diagnosed with recurrent metastatic breast cancer. The patient was diagnosed with breast cancer 11 years ago and underwent a mastectomy and subsequent adjuvant therapy. Tamoxifen had been given for 5 years, and the treatment was completed. Five years after, she found a lung nodule on her routine chest X-ray examination. Based on her past medical history, systemic cancer work-up was done and it revealed multiple lesions in T10 vertebra, lungs, and mediastinal lymph nodes. Trans-bronchial needle aspiration was performed and the biopsy was a metastatic breast cancer. Brain MRI was taken as she was complaining of headache and it showed a welldefined, ovoid enhancing 0.9-cm nodule in the right prepontine cistern. Neuro-oncology tumor board evaluated the lesion as more likely to be an asymptomatic neurogenic tumor rather than metastasis based on radiological features including brainstem surfaced location, slightly high signal intensity on T2-weighted image and no diffusion restriction. To rule out leptomeningeal metastasis, a serial cerebrospinal fluid cytology examination (×3) was done and negative for malignant cells. Follow-up brain MRIs of 2 and 9 months showed no significant changes in the pre-pontine enhancing lesion.

Keyword

Breast cancer; Metastasis; Cranial nerve; Neurilemmoma

Figure

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  Fig. 1 A series of radiological examinations led to a diagnosis of metastatic breast cancer (A) chest X-ray revealed left upper lower peribronchial nodule, (B) positron emission tomography CT scan showed multiple abnormal hyper-uptake suggesting possible multiple metastasis of lung, thoracic spine, and lymph nodes, and (C) chest CT revealed a nodule of left lower lobe. It is a location that can be biopsied through needle aspiration.

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  Fig. 2 Brain MRI, taken at the time of metastatic breast cancer diagnosis revealed a 0.9-cm diameter, pre-pontine mass lesion. A and B: The lesion was iso to low signal intensity on T1-weighted and T2-weighted images. C: There is no diffusion restriction on apparent diffusion coefficient maps. D: The lesion was well-enhanced with gadolinium. These findings were compatible with neurogenic tumor.

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  Fig. 3 Follow-up MRI, taken 2 months (A and B) and 9 months (C and D) after the initial brain MRI showed no change in size at the same cut. Metastasis at T1-weighted gadolinium-enhanced axial (A and C), and sagittal (C and D) images.

Reference

1. Acharya R, Husain S, Chhabra SS, Patir R, Bhalla S, Seghal AD. Sixth nerve schwannoma: a case report with literature review. Neurol Sci. 2003; 24:74–79. PMID: 12827543.

2. Harrison RA, Nam JY, Weathers SP, DeMonte F. Intracranial dural, calvarial, and skull base metastases. Handb Clin Neurol. 2018; 149:205–225. PMID: 29307354.

3. Gwak HS, Lee SH, Park WS, Shin SH, Yoo H, Lee SH. Recent advancements of treatment for leptomeningeal carcinomatosis. J Korean Neurosurg Soc. 2015; 58:1–8. PMID: 26279806.

4. Savage NM, Alleyne CH, Vender JR, Figueroa R, Zhang H, Samuel TA, et al. Dural-based metastatic carcinomas mimicking primary CNS neoplasia: report of 7 cases emphasizing the role of timely surgery and accurate pathologic evaluation. Int J Clin Exp Pathol. 2011; 4:530–540. PMID: 21738825.

5. Nayak L, Abrey LE, Iwamoto FM. Intracranial dural metastases. Cancer. 2009; 115:1947–1953. PMID: 19241421.

6. Deora H, Srinivas D, Beniwal M, Vikas V, Rao KVLN, Somanna S. Rare cranial nerve schwannomas: a retrospective review of nontrigeminal, nonvestibular cranial nerve schwannomas. J Neurosci Rural Pract. 2018; 9:258–263. PMID: 29725180.

7. Ivanova M, Porta FM, Giugliano F, Frascarelli C, Sajjadi E, Venetis K, et al. Breast cancer with brain metastasis: molecular insights and clinical management. Genes (Basel). 2023; 14:1160. PMID: 37372340.

8. Frechette KM, Breen WG, Brown PD, Sener UT, Webb LM, Routman DM, et al. Radiotherapy and systemic treatment for leptomeningeal disease. Biomedicines. 2024; 12:1792. PMID: 39200256.

9. Lee SK, Moon KS, Lee KH, Jung S. Cystic abducens schwannoma without abducens paresis: possible role of cisternal structures in clinical manifestation. J Korean Neurosurg Soc. 2013; 53:374–376. PMID: 24003375.

10. Li X, Li J, Li J, Wu Z. Schwannoma of the 6th nerve: case report and review of the literature. Chin Neurosurg J. 2025; 1:5.