Metastatic skull base tumor from thymic carcinoma mimicking Tolosa-Hunt syndrome

A case of brain metastasis of a thymic carcinoma with a review of the literature

Thymic epithelial tumors (TET) are rare lesions. The brain metastases of these tumors are even rarer. We report a case of brain metastases in a known patient with a thymic carcinoma diagnosed in October 2016. She was a 73-year-old woman who presented with headache, nausea, and right hemiplegia. Brain MRI revealed five lesions (1 insular, 1 frontal and 2 left temporal, 1 right parafalcine). These lesions were initially treated using two stereotactic radiosurgery gamma knives. A macroscopically complete excision of the left frontal lesion was subsequently performed without any complications with a good evolution of the neurological symptoms postoperatively. Immunohistochemical examination was compatible with metastatic thymic carcinoma. The patient died 14 months after the initial diagnosis. A review of the literature in English has reported another 45 TET cases with brain metastases.

Thymic epithelial tumors and metastasis to the brain: a case series and systematic review

Background

Thymic epithelial tumors (TETs) rarely metastasize to the brain. Clinico-pathologic features of TET patients with brain metastasis are not well described.

Methods

TET patients referred for consultation or screening for clinical trials are included. Imaging to evaluate for brain metastases was performed when clinically indicated or if required for screening. Tumor tissue from brain metastases was obtained for analysis, when available. Clinical characteristics and survival was evaluated and a systematic review of the literature on brain metastases associated with TETs was performed.

Results

Fourteen TET patients with brain metastasis were identified. Median age at TET diagnosis was 53 years (range: 31-71 years). Twelve patients had thymic carcinoma and two patients had World Health Organization B3 thymoma. Median time from TET diagnosis to discovery of brain metastases was 2.5 years (range: 9 months-8.3 years). Eleven patients had extracranial, extrathoracic metastases during presentation with brain metastases. Three patients underwent surgery and radiation therapy, eight patients received radiation therapy alone, and one patient had surgery alone. One patient with thymoma died 11 months after diagnosis of brain metastases and another patient died but with unknown date of diagnosis of brain metastases. Among 12 patients with thymic carcinoma, 11 of whom had a known date of brain metastases diagnosis, the median potential follow-up is 35.8 months, and median overall survival (OS) from diagnosis of brain metastases is 13.1 months.

Conclusions

Although uncommon, patients with advanced thymic carcinoma can develop brain metastases. Appropriate imaging and aggressive treatment should be considered for these patients.

Prevalence and Surgical Implications of Dural Enhancement at the Porus Acusticus in Vestibular Schwannomas

OBJECTIVE

Demonstrate the association of radiographic dural enhancement with increased tumor adherence at the porus acusticus, which may influence completeness of resection and facial nerve outcome.

STUDY DESIGN

Case series with chart review.

SETTING

Academic referral center.

SUBJECTS AND METHODS

A total of 205 consecutive patients with histopathologically confirmed vestibular schwannoma (VS) were evaluated. Patients with tumors exhibiting dural enhancement on postgadolinium T1-weighted magnetic resonance imaging were identified and compared with matched controls. Completeness of resection, intraoperative details, and facial nerve outcomes were analyzed.

RESULTS

Excluding strictly intracanalicular tumors (n = 32, 16%) and those with NF2 (n = 10, 4.9%), the presence of dural enhancement was radiographically confirmed in 16 (9.8%) cases. Paired analysis did not reveal significant baseline differences between cases and controls. Subtotal resection was performed in 5 (31%) of the 16 patients with tumors exhibiting dural enhancement, in contrast to 1 (3%) of the matched controls (P = .01). Four (25%) demonstrated increased tumor adherence at the porus acusticus intraoperatively, compared with 1 control (3%, P = .04). Long-term facial nerve function was similar between cases and controls (81% vs 84% House-Brackmann I-II function, P = 1.00).

CONCLUSION

Dural enhancement is present in approximately 10% of extracanalicular VS. Dural enhancement at the porus acusticus may represent hypervascularity, dural reaction, or infiltration, and portends increased tumor adherence and greater likelihood of subtotal resection to preserve facial nerve function. To our knowledge, this is the first series that reports the prevalence of this phenomenon in VS and the potential surgical implications. Recognition preoperatively may be valuable toward patient counseling.

Metastatic Thymic Carcinoma Presenting as a Posterior Fossa Mass: Case Report and Review of the Literature

BACKGROUND

Thymic epithelial tumors (TETs) are uncommon lesions, and cerebral metastases from these tumors are even rarer. We report a case of a posterior fossa metastasis in a patient with a known history of thymic carcinoma.

CASE DESCRIPTION

A 47-year-old man with a history of Hodgkin lymphoma and thymic carcinoma presented with headache, nausea, and ataxia. Imaging revealed a large posterior fossa mass. This lesion was completely resected without complications. Pathologic examination was consistent with metastatic thymic carcinoma. The patient's symptoms were relieved postoperatively. We reviewed the literature and identified an additional 44 cases of TETs with metastases to the brain. Although brain metastases are generally associated with a poor prognosis in patients with TETs, survival of more than 1 year may be accomplished with surgical resection and multimodality treatment.

CONCLUSIONS

Metastasis should be considered in the differential of a patient with a TET and an intracranial mass lesion.