Tumor-to-tumor metastasis inside a meningioma
There is a difference between Tumor-to-tumor metastasis and collision tumors. The former implies a recipient role of the host tumor, and the latter refers to a co-localization of two different tumors that grow into one another, both being in the same organ. Tumor-to-tumor brain metastasis is a well-described phenomenon but with unclear pathophysiology. Deeper knowledge could be beneficial for its management 1).
A tumor-to-tumor metastasis inside a meningioma is a rare phenomenon. Malignant neoplasms of the breast and lung are the most common primary tumors. Other sites of origin include prostate, renal and gastric neoplasms. A literature review was conducted in March 2020 via PubMed. Relevant search results were few 2)
Since some metastatic tumors have osteoblastic imaging pattern, it is not always easy to differentiate them from meningioma on preoperative studies 3).
Systematic review
Turner et al. located 124 articles, describing 152 cases of patients with Tumor-to-tumor metastasis inside a meningioma. The mean (± SD) age of all patients was 62.21 ± 10.8 years, with even distribution above and below the mean. Of the cases, 65.9% were reported in women. The most common cancer origins of TTMM were breast and lung carcinoma, followed by kidney, prostate, and GI tract carcinoma. Cancer status is not a good marker of TTMM when managing a meningioma. In 36.69% of cases, TTMM was the presentation of an unknown cancer. In nearly 60% of the known cases, cancer was considered in remission for at least 1 year. Meningioma parameters are unhelpful when considering a TTMM. The distribution of meningioma location is similar to other series of meningioma reported in the literature. Meningioma grade is similar to meningiomas without TTMM. In 57.89%, the patient presented with a focal deficit. Presenting factors were seizures, elevated ICP, and others. Over 95% of cases were symptomatic at presentation 4)
Case reports
A 73-year-old female patient diagnosed with breast cancer was found to have convexity meningioma. Since the size of tumor and peritumoral brain edema increased during follow-up period, the meningioma was treated with surgical resection. Postoperatively, histopathologic examination confirmed metastasis of invasive ductal carcinoma within a secretory meningioma. The final diagnosis was TTM of breast cancer in meningioma. Here, we report a rare case of intra-meningioma metastasis and a review of literature to provide a better understanding of this rare phenomenon 5)
A 60-year-old female referred complaining about a progressive headache, nausea, and vomiting for the past month. She had a history of breast cancer treated with radical mastectomy (5 years ago) and adjuvant chemotherapy (until 1 year ago). Workups revealed a dural-based mass in the left temporobasal and midline subfrontal regions. Histopathological study showed breast cancer metastasis nests within the primary meningioma
As the diagnosis of metastatic nests inside a benign tumor, drastically alters postoperative adjuvant treatments, a high index of suspicion is needed evaluating tumors from patients with a history of systemic neoplasms 6)
A 66-year-old female, with known Small-Cell Lung Cancer, who presented with left-sided hemiparesis. The Magnetic Resonance Imaging scan revealed a right frontal extraaxial mass. The patient underwent a craniotomy and a gross total resection of the tumor. Histological examination of the excised mass revealed metastatic adenocarcinoma deposits inside a meningioma: Tumor-to-tumor metastasis inside a meningioma. Reviewing the available literature, it has been hypothesized that the following factors play a role in the pathophysiology of this phenomenon: progesterone and estrogen receptors, cell-to-cell adhesion molecules, rich vascularization, favorable metabolic, micro-and immunological environment. Meningiomas seem to be the most common type of intracranial neoplasm to host a metastasis. 7).
Two patients are reported, with breast and renal carcinoma metastases in an intracranial meningioma 8)