Meningeal SWI/SNF related, matrix‐associated, actin‐dependent regulator of chromatin, subfamily B member 1 (SMARCB1)‐deficient tumours: an emerging group of meningeal tumours

Desmoplastic myxoid tumor, SMARCB1-mutant: a new variant of SMARCB1-deficient tumor of the central nervous system preferentially arising in the pineal region

Desmoplastic myxoid tumor (DMT), SMARCB1-mutant is a recently proposed brain tumor that occurs in the pineal region of adults. This tumor is characterized by desmoplastic stroma and various degrees of myxoid matrix. Tumor cells with low-grade morphology show polyphenotypic immunoreactivity, and rhabdoid cells are rare. We herein present a case with some uncommon features such as no myxoid stroma and slightly elevated proliferating activity. To date, knowledge on the variety of SMARCB1/INI1-deficient tumors of the central nervous system is gradually increasing, encompassing highly aggressive to slow-growing varieties. DMT, SMARCB1-mutant seems to be relatively benign, but careful attention is necessary because SMARCB1/INI1 deficiency is generally a genetic signature of concern.

SMARCB1 Gene Mutation Predisposes to Earlier Development of Glioblastoma: A Case Report of Familial GBM

Glioblastoma (GBM) is the most aggressive adult brain tumor. While GBM typically occurs sporadically, familial GBM can be associated with certain hereditary disorders and isolated familial GBMs in the absence of syndrome are rare. Relevant hereditary factors have remained elusive in these cases. Understanding specific genetic abnormality may potentially lead to better treatment strategies in these patients. Here, we analyzed GBM tissue from our patient and 2 afflicted family members, with next generation sequencing to better understand the genetic alterations associated with this disease development. DNA was extracted and sequenced and the data were then analyzed. Results revealed 2 common mutations in afflicted family members; PDGFRA and HRAS. In addition, both siblings showed a mutation of the SMARCB1 gene. The sister of our patient exhibited a homozygous mutation, while our patient had heterozygous mutation of this gene in the tumor tissue. This result suggests that mutation of SMARCB1, either alone or in the presence of PDGFRA and HRAS mutations, is associated with earlier onset GBM.

A case of desmoplastic myxoid tumor, SMARCB1 mutant, in the pineal region

Desmoplastic myxoid tumor (DMT), SMARCB1 mutant is a recently proposed new entity that mainly occurs in the pineal region and has epigenetic features similar to those of atypical teratoid/rhabdoid tumors (AT/RT)-MYC and poorly differentiated chordomas. Herein, we present a new case of a 33-year-old man with headaches, dizziness, nausea, vomiting, and blurred vision, who was initially found to have a suspicious germinoma on imaging. After surgical removal of the lesion, the postoperative pathological diagnosis was DMT, SMARCB1 mutant. To the best of our knowledge, this is the first case reported in China. Our findings also extend the range of the immunohistochemical phenotype of this rare tumor.

Fulminant presentation of a SMARCB1-deficient, anterior cranial fossa tumor in adult

Background:

Malignant atypical teratoid rhabdoid tumor (ATRT) usually develops in children. ATRTs are rare in adults, with only one case in the literature describing involvement of the anterior skull base. These primary intracranial tumors are characterized molecularly as SMARCB1 (INI1) deficient. Different types of such SMARCB1-deficient tumors exist in adulthood, usually in the form of extracranial tumors. Very few cases of such a new entity, named SMARCB1-deficient sinonasal carcinoma have been described with intracranial penetration and involvement of the anterior cranial fossa.

Case Description:

A 36-year-old male presented with acute cognitive deterioration. Over few hours, he developed a fulminant herniation syndrome. Imaging showed a tumor in the anterior cranial fossa surrounded by massive brain edema. The tumor has destroyed the frontal bone with involvement of the nasal cavities and paranasal sinuses. The patient underwent emergent decompressive craniectomy and tumor debulking but could not be saved. Pathological analysis revealed a highly cellular tumor without rhabdoid cells but with areas of necrosis. Further immunohistochemical stains revealed that neoplastic cells were diffusely and strongly positive for epithelial membrane antigen and P63 and negative for SMARCB1 (i.e., loss of expression), confirming the diagnosis of sinonasal carcinoma.

Conclusion:

To the best of our knowledge, this is the first report of a fulminant presentation of a SMARCB1- deficient tumor in young adult, involving the anterior cranial fossa and the paranasal sinuses. The main differential diagnosis of aggressive, primary, intracranial SMARCB1-deficient tumors in adults includes ATRT, SMARCB1- deficient sinonasal carcinoma, rhabdoid meningioma, and rhabdoid glioblastoma. Atypical tumors involving the anterior skull base without a clear histopathological pattern should therefore be checked for SMARCB1 expression.

Dural-based atypical teratoid/rhabdoid tumor in an adult: DNA methylation profiling as a tool for the diagnosis

Atypical teratoid/rhabdoid tumor (ATRT) is a malignant CNS embryonal tumor that mostly occurs in childhood, adult cases are rare. We report a case of a 23-year-old male with an extra-axial dura-based lesion in the left frontal area, previously diagnosed as gliosarcoma. After 6 years, the patient had a recurrence and the previous slides were reviewed. Tumor was positive for vimentin and negative for INI1. The differential diagnosis for this extra-axial tumor with long survival was rhabdoid meningioma with INI1 loss or ATRT. DNA methylation profiling was performed to reach the final and the most definitive diagnosis; the result was ATRT. Our case suggests the usefulness of DNA methylation profiling for diagnosing challenging CNS tumors.

Desmoplastic myxoid tumor, SMARCB1-mutant: clinical, histopathological and molecular characterization of a pineal region tumor encountered in adolescents and adults

Atypical teratoid/rhabdoid tumor (ATRT) is a highly malignant brain tumor predominantly occurring in infants. Mutations of the SMARCB1 gene are the characteristic genetic lesion. SMARCB1-mutant tumors in adolescents and adults are rare and may show uncommon histopathological and clinical features. Here we report seven SMARCB1-deficient intracranial tumors sharing distinct clinical, histopathological and molecular features. Median age of the four females and three males was 40 years (range 15-61 years). All tumors were located in the pineal region. Histopathologically, these tumors displayed spindled and epithelioid cells embedded in a desmoplastic stroma alternating with a variable extent of a loose myxoid matrix. All cases showed loss of nuclear SMARCB1/INI1 protein expression, expression of EMA and CD34 was frequent and the Ki67/MIB1 proliferation index was low in the majority of cases (median 3%). Three cases displayed heterozygous SMARCB1 deletions and two cases a homozygous SMARCB1 deletion. On sequencing, one tumor showed a 2 bp deletion in exon 4 (c.369_370del) and one a short duplication in exon 3 (c.237_276dup) both resulting in frameshift mutations. Most DNA methylation profiles were not classifiable using the Heidelberg Brain Tumor Classifier (version v11b4). By unsupervised t-SNE analysis and hierarchical clustering analysis, however, all tumors grouped closely together and showed similarities with ATRT-MYC. After a median observation period of 48 months, three patients were alive with stable disease, whereas one patient experienced tumor progression and three patients had succumbed to disease. In conclusion, our series represents an entity with distinct clinical, histopathological and molecular features showing epigenetic similarities with ATRT-MYC. We propose the designation desmoplastic myxoid tumor (DMT), SMARCB1-mutant, for these tumors.

SMARCB1- and vimentin-positive esophageal carcinoma with undifferentiated components, rhabdoid features, and a good prognosis: a case report

BACKGROUND

Undifferentiated carcinoma of the esophagus with rhabdoid features is a very rare histologic finding that is occasionally associated with the loss of SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1 (SMARCB1); however, until now, few survey reports of this type of tumor have been published. In this study, we describe a case of esophageal carcinoma with undifferentiated components and rhabdoid features that was exclusively positive for vimentin and SMARCB1 in a patient with prolonged survival.

CASE PRESENTATION

A 67-year-old man complained of a stomachache and loss of appetite persisting for 1 month. He was then admitted to the hospital. Diagnostic imaging studies revealed a transdiaphragmatic circular ulcerative tumor of the esophagogastric region. Biopsy specimens showed undifferentiated round cell carcinoma. The patient underwent lower esophageal resection and total gastrectomy with lymph node dissection. Microscopic analysis revealed that most of the primary tumor consisted of large undifferentiated round cells and scattered rhabdoid cells. The tumor invaded the muscular layer in the esophagus and the subserosal layer in the stomach, and metastasis was noted in only one lymph node. Immunohistochemical analysis revealed that the round and rhabdoid cells found in the primary tumor were diffusely positive for SMARCB1 and vimentin. The tumor displayed focal positivity for the anti-pan-cytokeratin antibody AE1/AE3. In the positive lymph node, round undifferentiated carcinoma cells were admixed with squamous carcinoma cells that were positive for cytokeratin 5/6 and 34βE12. The MIB-1 index was 19.7% and 0.5% for the round cells from the primary tumor and epithelial cells from the metastatic lymph node lesion, respectively, and 70.1% for the round cells from the metastatic lymph node lesion. The patient has been alive for 10 years after surgery without tumor recurrence.

CONCLUSIONS

We reported a rare case of esophageal carcinoma with undifferentiated components, rhabdoid features, and a good prognosis.

Primary intracerebral INI1-deficient rhabdoid tumor with CD34 immunopositivity in a young adult

Background:

Primary CNS malignant rhabdoid tumors are very rare in adults and much less is known about their biological behavior than in children. Recently, two adult cases of SMARCB1 (also known as INI1)-deficient tumor with rhabdoid cells have been described, suggesting an emerging group of primary meningeal SMARCB1-deficient tumors. We have recently encountered a case of INI1-deficient tumor with similar histology and immunophenotype to the above cases, but with a superficial cerebral, yet apparent intra-axial origin.

Case Description:

A 22-year-old woman presented with approximately one year history of focal sensorimotor right upper limb seizures and recently developed a slowly progressive weakness in her right hand. An MRI of the brain demonstrated an avidly enhancing lesion centered on the left perirolandic region with no definite dural involvement. The patient underwent a complete surgical excision. Histology revealed a tumor with monotonous epithelioid and spindle-shaped cells in a mucoid/myxoid background. There was focal mitotic activity and a few necrotic areas, in addition to many rhabdoid cells. The immunohistochemistry was negative for INI1 and there was strong positivity with CD34, while focal smooth muscle actin (SMA) and epithelial membrane antigen (EMA) immunoreactivity were also noted.

Conclusions:

As an addition to the two cases of adult SMARCB1-deficient tumors recently described, we present a further adult case with a similar immunohistochemical profile but with an apparent intra-axial origin, questioning the necessary meningeal origin of this type of tumor. The prognosis of this adult INI1/SMARCB1-deficient tumor is to be determined, but may be better than the pediatric atypical/teratoid tumor (AT/RT).