CNS & pituitary tumors
Pineal tumors
Desmoplastic myxoid tumor of the pineal region, SMARCB1 mutant
Editorial Board Member: Meaghan Morris, M.D., Ph.D.
Deputy Editor-in-Chief: Chunyu Cai, M.D., Ph.D.
Last author update: 8 July 2022
Last staff update: 8 July 2022
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PubMed Search: Desmoplastic myxoid tumor, SMARCB1 mutant
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Laboratory | Radiology description | Radiology images | Prognostic factors | Case reports | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Voudouri M, Zanazzi G. Desmoplastic myxoid tumor of the pineal region, SMARCB1 mutant. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumorSMARCB1mutant.html. Accessed April 25th, 2024.
Definition / general
- Pineal region neoplasm with ovoid or spindle shaped cells, containing inactivating alterations of the SMARCB1 / INI1 locus and variable amounts of desmoplasia and myxoid matrix
Essential features
- Predominates in adults and adolescents
- Arises in the pineal region
- Small to medium sized cells with ovoid to spindle shaped nuclei
- Variable amounts of desmoplasia and myxoid matrix
- Inactivating SMARCB1 / INI1 alteration
Terminology
- Desmoplastic myxoid tumor of the pineal region, SMARCB1 mutant
ICD coding
- ICD-11: 2A00.20 - tumors of the pineal gland or pineal region
Epidemiology
- Incidence data not yet available
- M:F = 2:3 (Neuro Oncol 2022;24:847)
- Median patient age: 36.6 years old (Neuro Oncol 2022;24:847)
- Patient age range: 15 - 61 years old (Neuro Oncol 2022;24:847)
Sites
- Pineal region
Pathophysiology
- Precise pathophysiology is unclear
Etiology
- Precise etiology is unclear
Clinical features
- Sequelae of obstructive hydrocephalus, such as blurred vision, headache, nausea, vomiting, dizziness
Diagnosis
- Identification of SMARCB1 / INI1 inactivating alteration and protein loss
Laboratory
- Serum and cerebrospinal fluid alpha fetoprotein and beta human chorionic gonadotropin are normal
Radiology description
- MRI: T1 hypointense to slightly hyperintense, T2 / fluid attenuated inversion recovery (FLAIR) hyperintense, contrast enhancing (Neuropathology 2021;41:37, Virchows Arch 2021;479:835)
Radiology images
Contributed by Yue-E Wang, M.S., Ph.D., Jingjing Chen, Ph.D., Wei Wang, Ph.D., An-Li Zhang, M.D., Wenchao Zhou, Ph.D. and Hai-Bo Wu, M.D., Ph.D.
MRI - sagittal T1
MRI - sagittal T2
Prognostic factors
- Prognostic factors are not yet defined but reported prognosis much better than atypical teratoid / rhabdoid tumor
- 70% of reported patients are alive without recurrence, with a median follow up of 29.5 months (0 months - 7 years) (Neuro Oncol 2022;24:847)
Case reports
- 24 year old woman with a myxoid tumor of the pineal region (Free Neuropathol 2021;2:14)
- 29 year old woman with hemorrhagic pineal region mass (Virchows Arch 2021;479:835)
- 33 year old man with pineal region mass (Neuropathology 2021;41:37)
Treatment
- Surgical resection is the treatment of choice
- Chemotherapy or radiotherapy has been given to a subset of patients (Neuro Oncol 2022;24:847)
Microscopic (histologic) description
- Epithelioid to spindle shaped cells embedded in a desmoplastic stroma and loose myxoid matrix
- Rhabdoid cells may be rare
- No high grade / malignant features such as brisk mitotic activity and tumor necrosis
- Reference: Acta Neuropathol 2020;139:277
Microscopic (histologic) images
Contributed by Mariana Voudouri, M.D. and George Zanazzi, M.D., Ph.D.
Epithelioid neoplasm with desmoplasia
Cellular atypia
Perivascular tumor cell accumulation
CD34
SMARCB1 / INI1
Contributed by Branavan Manoranjan, M.D., Ph.D., Abdelsimar T. Omar II, M.D., Hai-Bo Wu, M.D., Ph.D., Robert Nordal, M.D. and Yves Starreveld, M.D., Ph.D.
Microcysts and myxoid matrix
Trichrome
Positive stains
- CD34 (variably positive) (Acta Neuropathol 2020;139:277)
- EMA (variably positive) (Acta Neuropathol 2020;139:277)
- Vimentin (variably positive) (Acta Neuropathol 2020;139:277, Neuropathology 2021;41:37)
Negative stains
Molecular / cytogenetics description
- Defined by SMARCB1 / INI1 inactivating alterations
- DNA methylation profile clusters adjacent to atypical teratoid / rhabdoid tumor - MYC and poorly differentiated chordomas
- Reference: Acta Neuropathol 2020;139:277
Sample pathology report
- Pineal region tumor, resection:
- Desmoplastic myxoid tumor of the pineal region, SMARCB1 mutant (see comment)
- Molecular information: SMARCB1 / INI1 loss of nuclear expression
- Immunohistochemistry: consistent with mutant
- Comment: A CNS WHO grade has not yet been assigned to this tumor entity.
Differential diagnosis
- Meningioma:
- No SMARCB1 / INI1 inactivating alteration
- Solitary fibrous tumor:
- No SMARCB1 / INI1 inactivating alteration
- NAB2::STAT6 fusion with upregulated STAT6 expression
- Chordoma:
- Nuclear brachyury
- Cribriform neuroepithelial tumor:
- Cribriform architecture
- Predominantly in young children
- Tyrosinase staining
- Atypical teratoid / rhabdoid tumor, CNS WHO grade 4:
- Malignant with frequently increased mitotic activity and necrosis
- Predominantly in young children
Board review style question #1
A 35 year old woman presents with progressively worsening blurred vision, headache, nausea and vomiting. MRI shows a pineal region mass with areas of contrast enhancement. A representative hematoxylin and eosin stained image of the tumor is shown. The tumor cells are CD34 positive and exhibit loss of nuclear SMARCB1 / INI1. The diagnosis is consistent with which of the following?
- Desmoplastic myxoid tumor of the pineal region, SMARCB1 mutant
- Germinoma
- Meningioma, CNS WHO grade 1
- Pineocytoma, CNS WHO grade 1
Board review style answer #1
A. Desmoplastic myxoid tumor of the pineal region, SMARCB1 mutant
Comment Here
Reference: Desmoplastic myxoid tumor, SMARCB1 mutant
Comment Here
Reference: Desmoplastic myxoid tumor, SMARCB1 mutant
Board review style question #2
A 28 year old man undergoes resection of a pineal region tumor. A representative hematoxylin and eosin stained section reveals spindled to epithelioid tumor cells embedded in a variably myxoid matrix and desmoplastic stroma. The Ki67 proliferation index is 4%. Which gene would you expect to be mutated?
- ATRX
- DICER1
- EWSR1
- SMARCB1
Board review style answer #2
