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Year : 2021  |  Volume : 4  |  Issue : 1  |  Page : 12-14

A case report of atypia in angiomatous microcystic meningioma: A mimicker and masker of intratumoral metastasis in a patient with no known systemic malignancy

1 Department of Pathology, National University Health System, Singapore
2 Division of Neurological Surgery, Ng Teng Fong General Hospital, Singapore

Date of Submission29-Dec-2020
Date of Decision01-Feb-2021
Date of Acceptance08-Feb-2021
Date of Web Publication30-Mar-2021

Correspondence Address:
Dr. Char Loo Tan
Department of Pathology, National University Hospital, 5 Lower Kent Ridge Road, Main Building, Level 3, 119074
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/glioma.glioma_31_20

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Intratumoral metastasis is rare, and in the brain, meningiomas are the most common type of primary brain tumors to harbor metastases. We report a case of angiomatous microcystic meningioma associated with intratumoral metastatic lung adenocarcinoma in a patient with no prior history of malignancy, in which the pronounced atypia of the meningioma potentially mimics or masks the minute focus of metastatic cancer. A meticulous search for intratumoral metastasis within the meningioma is recommended if metastasis is clinically suspected. A formal ethical approval for the single case report is waived by the Institutional Review Board of National University Health System, Singapore.

Keywords: Angiomatous microcystic, case report, intratumoral metastasis, meningioma, metastasis

How to cite this article:
Tan HM, Low SW, Tan CL. A case report of atypia in angiomatous microcystic meningioma: A mimicker and masker of intratumoral metastasis in a patient with no known systemic malignancy. Glioma 2021;4:12-4

How to cite this URL:
Tan HM, Low SW, Tan CL. A case report of atypia in angiomatous microcystic meningioma: A mimicker and masker of intratumoral metastasis in a patient with no known systemic malignancy. Glioma [serial online] 2021 [cited 2023 Oct 2];4:12-4. Available from: http://www.jglioma.com/text.asp?2021/4/1/12/312467

  Introduction Top

Brain metastases, also known as secondary brain tumors, are the most common type of intracranial tumor in adults.[1] Rarely, metastases can be found within a primary brain tumor, in the form of tumor-to-tumor metastasis, or as a collision tumor. Meningioma appears to be the most common type of primary brain tumor to harbor brain metastasis, with breast and lung cancers being the most common sources of metastases.[2],[3] The phenomenon of angiomatous meningioma harboring a metastatic tumor has only been reported in two previous cases, to the best of our knowledge.[4],[5] We report the third case of meningioma of mixed angiomatous and microcystic variants harboring a tiny focus of metastatic lung adenocarcinoma, in a patient with no known systemic malignancy. Our case illustrates the marked degenerative nuclear atypia associated with angiomatous microcystic variant of meningioma, a potential diagnostic pitfall that may mimic or mask the concurrent metastatic tumor.

  Case Report Top

A 63-year-old female with no known past medical history presented with memory issues and incoherent speech lasting for 2 weeks and left-sided hemiparesis that lasted for 3 days. On examination, left-sided facial droop and hemiparesis were identified. Magnetic resonance imaging of the brain revealed multiple heterogeneously enhanced intra-axial lesions, including one located high in the right parasagittal frontal lobe, which likely accounted for the clinical symptoms of left hemiparesis [Figure 1]A. The largest mass was 4 cm, located in the left basifrontal lobe, and appeared to be dural based. It was associated with marked vasogenic edema and subfalcine midline shift [Figure 1]B. The multifocal intracranial involvement was highly suggestive of a metastatic disease. A systemic workup subsequently revealed a 1.7-cm spiculated nodule in the left upper lobe of the lung. No pathologic confirmation of the lung nodule was performed. Instead, a decision was made to remove the left frontal lobe tumor, because this lesion was causing a significant mass effect. As the left frontal lobe tumor also had some radiological characteristics of a meningioma, the possibility of dual pathology involvement was initially deliberated. If the histology eventually revealed a meningioma, biopsy of the other lesions would subsequently be considered.
Figure 1: Magnetic resonance imaging of the brain in a patient with no known systemic malignancy (A) Right parasagittal frontal tumor (black arrow) causing weakness. (B) Left dural-based basifrontal tumor with a dural tail (white arrow) and marked vasogenic edema (black arrowheads)

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The histological examination of the resected brain tumor revealed meningothelial cells with a whorled, angiomatous and microcystic architecture, associated with prominent degenerative nuclear atypia [Figure 2]A. Mitotic activity was up to 1 per 10 high-powered fields. No tumor necrosis, prominent nucleoli, sheeting, small cell change, or increased cellularity was observed. In addition, a minute focus of polygonal cells was identified, and these cells displayed a higher degree of nuclear atypia, distinct nucleoli, high nuclear-cytoplasmic ratio, and basophilic cytoplasm, which contrasted with the adjacent meningothelial proliferation [Figure 2]B. This tumor focus constituted <5% of the entire specimen volume and showed positive immunoreactivity for cytokeratin CAM5.2, cytokeratin 7, thyroid transcription factor 1 [Figure 2]C, and Napsin A, none of which were detected in the background meningothelial proliferation. In contrast, the latter showed strong nuclear immunoreactivity for progesterone receptor [Figure 2]D. A diagnosis of meningioma, angiomatous, and microcystic variants, World Health Organization Grade 1, with intratumoral metastatic lung adenocarcinoma, was made. Biopsy of the lung tumor was hence not required, and the patient was offered palliative chemoradiotherapy in view of the advanced stage of lung cancer.
Figure 2: Histology images of the brain tumor. Hematoxylin and eosin-stained sections showed (A) meningioma with mixed angiomatous, microcystic patterns and whorls with pronounced degenerative-type nuclear atypia (yellow arrowheads). (B) Low-power view of the meningioma (left) with adjacent metastatic adenocarcinoma (right; yellow arrowheads demarcating boundary of the metastatic adenocarcinoma). (C) Thyroid transcription factor 1 immunohistochemical stain was positive in the metastatic adenocarcinoma (same area of tumor as in image B). (D) The meningothelial proliferation showed positivity for progesterone receptor in contrast to the metastatic tumor focus (same area of tumor as in image B). Scale bars: 300 μm in A, 400 μm in B–D

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The ethical approval for the single case report is waived by the Institutional Review Board of National University Health System, Singapore. A written consent was obtained from the patient. The collection and usage of information in this study were conducted in full compliance with all the principles of the Declaration of Helsinki.

  Discussion Top

Most meningiomas that serve as host tumor for a metastasis have been reported to be of the meningothelial, fibrous, or transitional subtypes, likely because these are the most common histological variants of meningioma, and their low metabolic rate serves as a noncompetitive metabolic environment for the metastasis to grow.[6] Conversely, the rare occurrence of angiomatous meningioma harboring a metastatic tumor is probably attributed to it being an uncommon histological subtype. The enhanced vascularity of angiomatous meningioma serves as a good nidus to “catch” tumor emboli.[5]

Notably, angiomatous meningioma often coexists with the microcystic meningioma subtype and is associated with marked cerebral edema, beyond that expected for its size, which was observed in our case.[7] In addition, these tumors often show marked degenerative nuclear atypia which may be alarming to pathologists who are not familiar with this phenomenon. Moreover, the pronounced nuclear atypia observed in the meningioma may mask the presence of a concurrent metastatic tumor, especially in cases with no prior suspicion of metastatic tumor or when the metastatic component represents a minute focus of the meningioma, as was observed in our case. Therefore, in patients with a known or suspected metastatic malignancy, a meticulous search for the presence of a metastatic tumor should be performed within the meningioma through extensive sampling and a judicious use of immunohistochemical stains. Meningiomas, including the anaplastic variants, classically show limited or negative expression for cytokeratin with the exception of secretory meningioma which expresses cytokeratin in the tumor cells around the pseudopsammoma bodies. In addition, meningiomas commonly express reactivity for progesterone receptor, with a staining pattern inversely proportional to grade. Epithelial membrane antigen, being the most common used immunomarker for meningioma, is not useful in this context as both meningioma and metastatic carcinomas express epithelial membrane antigen, although it is usually stronger in carcinoma.[8] Finally, once a metastatic carcinoma is confirmed, the source of the primary tumor can be narrowed down by correlation with the clinical history of malignancy or by application of lineage-specific antibodies, for example, thyroid transcription factor 1 for lung or thyroid, GATA3 for breast, etc.

In all, the resection of the left frontal lobe tumor not only relieved the intracranial mass effect and alleviated the patient's neurological symptoms but also enabled the diagnosis of metastatic lung adenocarcinoma to be made, providing a valuable tissue sample for further molecular testing and saving the patient from undergoing a second invasive procedure.

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Institutional review board statement

It is the authors' institution's policy that a formal ethical approval for single case report is not required. The collection and usage of information in this study were conducted in full compliance with all principles of the Declaration of Helsinki.

Declaration of patient consent

The authors certify that they have obtained the patient's consent for the publication. In the consent form, the patient has given her consent for her radiological and histological images, as well as relevant clinical information, to be reported in the journal. The patient understands that identifiable information will not be published and due efforts will be made to conceal her identity.

Conflicts of interest

There are no conflicts of interest.

  References Top

Valiente M, Ahluwalia MS, Boire A, Brastianos PK, Goldberg SB, Lee EQ, et al. The evolving landscape of brain metastasis. Trends Cancer 2018;4:176-96.  Back to cited text no. 1
Caroli E, Salvati M, Giangaspero F, Ferrante L, Santoro A. Intrameningioma metastasis as first clinical manifestation of occult primary breast carcinoma. Neurosurg Rev 2006;29:49-54.  Back to cited text no. 2
Syed S, Karambizi DI, Baker A, Groh DM, Toms SA. A comparative report on intracranial tumor-to-tumor metastasis and collision tumors. World Neurosurg 2018;116:454-63.  Back to cited text no. 3
Ravnik J, Ravnik M, Bunc G, Glumbic I, Tobi-Veres E, Velnar T. Metastasis of an occult pulmonary carcinoma into meningioma: A case report. World J Surg Oncol 2015;13:292.  Back to cited text no. 4
Best PV. Metastatic carcinoma in a meningioma: Report of a case. J Neurosurg 1963;20:892-4.  Back to cited text no. 5
Nada A, Abdelrahman A, Cunningham C, Cousins J. Radio-pathological review of a metastatic renal cell carcinoma within a meningioma: A case report of collision tumor. Radiol Case Rep 2020;15:637-40.  Back to cited text no. 6
Zakhari N, Torres C, Castillo M, Nguyen TB. Uncommon cranial meningioma: Key imaging features on conventional and advanced imaging. Clin Neuroradiol 2017;27:135-44.  Back to cited text no. 7
Perry A. Meningiomas. In: Perry A, Brat DJ, eds. Practical Surgical Neuropathology: A Diagnostic Approach. 2nd ed. Philadelphia, PA: Elsevier; 2017:259-98.  Back to cited text no. 8


  [Figure 1], [Figure 2]


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