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Introduction: Highly aggressive thoracic neoplasms characterized by SMARCA4 (BRG1) deficiency and undifferentiated round cell or rhabdoid morphology have been recently described and proposed to represent thoracic sarcomas. However, it remains unclear whether such tumors may instead represent sarcomatoid carcinomas, and how their clinicopathologic characteristics compare with those of nonsarcomatoid SMARCA4-deficient non–small cell lung carcinomas (SD-NSCC). Methods: We identified 22 SMARCA4-deficient thoracic sarcomatoid tumors (SD-TSTs) with round cell and/or rhabdoid morphology and 45 SD-NSCCs, and comprehensively analyzed their clinicopathologic, immunohistochemical, and genomic characteristics using 341–468 gene next-generation sequencing and other molecular platforms. Results: The relationship of SD-TSTs with NSCC was supported by (1) the presence of NSCC components juxtaposed with sarcomatoid areas in five cases, (2) focal expression of NSCC lineage markers TTF1 or p40 in four additional cases, (3) smoking history in all except one patient (mean = 51 pack-years), accompanied by genomic smoking signature, and (4) high tumor mutation burden (mean = 14.2 mutations per megabase) and mutations characteristic of NSCC in a subset. Compared with SD-NSCCs, SD-TSTs exhibited considerably larger primary tumor size (p < 0.0001), worse survival (p = 0.004), and more frequent presentation at younger age (30–50 years) despite heavier smoking history. Distinctive pathologic features of SD-TSTs included consistent lack of adhesion molecule claudin-4, SMARCA2 (BRM) codeficiency, and frequent expression of stem cell markers. Conclusions: SD-TSTs represent primarily smoking-associated undifferentiated/de-differentiated carcinomas rather than primary thoracic sarcomas. Despite their histogenetic relationship with NSCC, these tumors have unique clinicopathologic characteristics, supporting their recognition as a distinct entity. Further studies are warranted to determine therapeutic approaches to this novel class of exceptionally aggressive thoracic tumors.

Rhabdoid tumor commonly occurs in the kidney and has an aggressive clinical course with high mortality. Extrarenal rhabdoid tumours can involve a number of organs, but poorly differentiated follicular carcinoma with rhabdoid phenotype is an extremely rare clinical entity. The 18F-FDG PET feature of this thyroid malignancy is not available in the literature to the best of our knowledge. But, this feature has significant clinical relevance in management of such patients. We present such a case.

Background Undifferentiated carcinoma of the biliary tract are highly aggressive malignancies. In other organs, a subgroup of undifferentiated carcinoma related to SWI/SNF complex–deficiency have been described. Case presentation A 30-year-old woman presented with rising inflammatory markers (C-reactive protein (CRP)). Ultrasound examination revealed a large tumor of the liver. A computed tomography scan was performed and was primarily interpreted as a tumor-forming liver abscess, possibly caused by gallbladder perforation. Subsequent liver segment resection was performed. Microscopic examination showed an undifferentiated carcinoma with rhabdoid morphology and prominent inflammatory infiltrate in the gallbladder base. With SWI/SNF immunohistochemistry, intact expression of SMARCB1, SMARCA4, ARID1A, but loss of SMARCA2 and PBRM1 was detected. Next-generation-sequencing detected KRAS, PBRM1 and ARID1B mutations, a deleterious splice-site mutation in the POLE-gene and a mutation in the TP53-gene. Conclusions We were able to demonstrate loss of SMARCA2 expression and mutations characteristic of an SWI/SNF-deficient carcinoma in a tumor derived from the gallbladder. This is the first reported case of an undifferentiated carcinoma with rhabdoid features in the gallbladder carrying a POLE mutation and SWI/SNF-deficiency of PBRM1 and SMARCA2. Supplementary Information The online version contains supplementary material available at 10.1186/s13000-021-01112-4.

Angiomatoid fibrous histiocytoma (AFH) is an uncommon soft-tissue neoplasm that arises mostly in the extremities of young people and generally carries a good prognosis. Intracranial location is unusual and frequently associated with myxoid change. EWSR1 gene fusions with members of the CREB family (CREB1, ATF1, and CREM) are well-established events in AFH. These fusions have also been described in other neoplasms including intracranial myxoid mesenchymal tumor, and it is still uncertain whether the latter is a distinct entity or if it represents a myxoid variant of AFH. Here, we describe a rare falcine AFH presenting in a 50-year-old woman. The most striking feature of this tumor was its diffuse rhabdoid morphology with focal high mitotic activity, raising the consideration of rhabdoid meningioma (WHO grade III). The tumor cells were moderately positive for EMA and negative for progesterone receptor and SSTR2 prompting additional studies. Desmin was strongly positive and CD99 showed membranous immunoreactivity. BAP1, INI-1, and BRG1 expressions were retained. Next-generation sequencing analysis demonstrated an EWSR1-ATF1 gene fusion, supporting the diagnosis of an unusual rhabdoid variant of AFH. After gross total resection of this tumor, the patient remains free of disease 5 months after the surgery without additional treatment.

Renal cell carcinoma with rhabdoid features is a rare histopathologic variant recently documented. It is a very aggressive tumor and associated with a higher mortality rate and poor prognosis. A 22 years old female patient presents with a rare case of clear cell renal cell carcinoma with rhabdoid features successfully managed with right radical nephrectomy and paracaval lymph node excision. The patient was alive, healthy and three years of flow up for the patient was free from metastasis. Despite rhabdoid features are lethal tumors and are associated with higher grades, radical nephrectomy with lymph node dissection increases survival rate.

The case of a heavy ex‐smoking man in his early 70s who presented with haemoptysis and died following rapid progression is presented. The tumour excised by surgery was mostly composed of monotonous large rhabdoid cells showing prominent nucleoli and eosinophilic cytoplasm. On immunohistochemistry with SMARCA4 (BRG‐1), the tumour cells showed significant loss of expression. The tumour was diagnosed as a SMARCA4‐deficient thoracic sarcoma. This is a disease that progresses rapidly and has a poor prognosis. However, the search for specific treatments using synthetic lethality is underway. Clinical and pathological characteristics can be identified with examination of more cases, and when the tumour is suspected, it is necessary to actively perform immunohistochemical examination., We present the case of a heavy ex‐smoking man in his early 70s who presented with haemoptysis and died following rapid progression. The excised tumour was diagnosed as a SMARCA4‐deficient thoracic sarcoma. This is a disease that progresses rapidly and has a poor prognosis.

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.

Extra-cranial rhabdoid tumors (RT) are highly aggressive malignancies of infancy, characterized by undifferentiated histological features and loss of SMARCB1 expression. The diagnosis is all the more challenging that other poorly differentiated cancers lose SMARCB1 expression, such as epithelioid sarcomas (ES), renal medullary carcinomas (RMC) or undifferentiated chordomas (UC). Moreover, late cases occurring in adults are now increasingly reported, raising the question of differential diagnoses and emphasizing nosological issues. To address this issue, we have analyzed the expression profiles of a training set of 32 SMARCB1-deficient tumors (SDT), with ascertained diagnosis of RT (n = 16, all < 5 years of age), ES (n = 8, all > 10 years of age), UC (n = 3) and RMC (n = 5). As compared with other SDT, RT are characterized by an embryonic signature, and up-regulation of key-actors of de novo DNA methylation processes. Using this signature, we then analysed the expression profiling of 37 SDT to infer the appropriate diagnosis. Thirteen adult onset tumors showed strong similarity with pediatric RT, in spite of older age; by exome sequencing, these tumors also showed genomic features indistinguishable from pediatric RT. In contrary, 8 tumors were reclassified within carcinoma, ES or UC categories, while the remaining could not be related to any of those entities. Our results demonstrate that embryonic signature is shared by all RT, whatever the age at diagnosis; they also illustrate that many adult-onset SDT of ambiguous histological diagnosis are clearly different from RT. Finally, our study paves the way for the routine use of expression-based signatures to give accurate diagnosis of SDT.

Small cell carcinoma of the ovary, hypercalcemic type, (SCCOHT) is the most common undifferentiated ovarian cancer in women aged under 40 years. SCCOHT is a monogenic disease, characterized by germline and somatic SMARCA4 mutations. Recent studies have stressed its morphological and clinical similarity to malignant rhabdoid tumours, which are usually caused by mutations in the related gene, SMARCB1. While familial tumours are rare, the incidence of germline mutations is relatively high, with up to 43% of SCCOHTs and 35% of rhabdoid tumours caused by germline mutations in SMARCA4 and SMARCB1, respectively. We report two new familial cases of SCCOHT. Affected members in both families and the associated tumours were found to carry SMARCA4 germline and somatic mutations, respectively, leading to loss of SMARCA4 protein expression in the tumours. Despite the rarity of familial SCCOHT, the high incidence of germline mutations is important to note, as without a family history of the disease, the hereditary nature of SCCOHT may be missed, especially if the mutation was inherited from the father or acquired de novo. The similarity between SCCOHT and rhabdoid tumours should be recognized, as infant carriers of SMARCA4 mutations may be at risk for these tumours in addition to SCCOHT.

Papillary and rhabdoid meningiomas are pathologically World Health Organization (WHO) grade III. Any correlation between clinical prognosis and pathologic component is not clear. We analyzed the prognoses of patients with meningiomas with a rhabdoid or papillary component compared to those of patients with anaplastic meningiomas. From 1994 to June 2013, 14 anaplastic meningiomas, 6 meningiomas with a rhabdoid component, and 5 meningiomas with papillary component were pathologically diagnosed. We analyzed magnetic resonance imaging (MRI) findings, extent of removal, adjuvant treatment, progression-free survival (PFS), overall survival (OS), and pathologic features of 14 anaplastic meningiomas (group A), 5 meningiomas with a predominant (≥50%) papillary or rhabdoid component (group B1), and 6 meningiomas without a predominant (

Meningioma is a common intracranial tumour which is usually benign. It is well-known to be high grade as atypical or anaplastic with grade II or III. Meningiomas are rarely found in paediatric patients. Extracranial metastasis from brain meningioma is rare but can occur in the lungs, pleura, liver, lymph node and bones. In this paper, we report a 16-year-old female with an extracranial metastasis of grade III meningioma to the lung. She underwent gross total resection along with chemo- and radiotherapy. The outcome and treatment modality would also be discussed.

Extrarenal rhabdoid tumors (ERRTs) are extremely rare neoplasms; of these, colorectal ERRTs are the most rare, and only nine cases have been previously described in the English language literature. The current study reports the pathological features of a case of poorly differentiated cecal adenocarcinoma with prominent rhabdoid feature, which was combined with mucinous cystadenoma of the appendix in a 73-year-old male, and additionally reviews the previously reported cases. Microscopically, the majority of tumor cells were non-cohesive or loosely cohesive, with a polygonal morphology and prominent rhabdoid feature, showing eccentric vesicular nuclei, prominent nucleoli and abundant eosinophilic cytoplasm. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) and vimentin, but negative for CK20, CK7, desmin and smooth muscle actin. This indicated a diagnosis of poorly differentiated adenocarcinoma with prominent rhabdoid features, combined with appendiceal mucinous cystadenoma. At two months following surgery the patient succumbed to peritoneal seeding and metastasis of liver and bone The emergence of the rhabdoid phenotype is invariably associated with an aggressive and almost always fatal clinical course. The present case is the 10th example of such a tumor in the colon, and to the best of our knowledge, this is the first case of colonic rhabdoid tumor coinciding with appendiceal benign mucinous neoplasm.

Highlights • The third case of pure primary malignant rhabdoid tumor of the ovary (MRTO) is described • SMARCA4 and SMARCB1 genetic analysis and immunohistochemistry are necessary for correct diagnosis of MRTO • MRTO and small cell carcinoma of the ovary, hypercalcemic type are essentially the same and should be treated as such

We reported a case of meningioma with rhabdoid morphology but lacking histological features of malignancy in arising from the spinal cord in a 28-year-old male. The tumor showed light microscopic, immunohistochemical evidence of meningothelial differentiation together with diffuse areas exhibiting rhabdoid morphology. The rhabdoid areas were characterized by cells with large cytoplasmic eosinophilic inclusions and eccentric nuclei. Unlike most cases reported in the literature, this case lacked significant mitotic activity and other atypical features. The diagnostic and prognostic significance of this tumor entity is discussed along with a review of the literature.

Meningiomas are common central nervous system tumors with a wide range of morphological variants, assigned World Health Organization (WHO) Grades I - III. We report an extremely rare rhabdoid, papillary and clear cell meningioma (WHO Grade III) in a 29-year-old female, who presented with diplopia and headache over a few days, 2 years ago. Magnetic resonance imaging showed a well-circumscribed, lobulated, predominantly solid and contrast-enhancing lesion in the right temporal, parietal and occipital lobes. On routine staining, the tumor did not display classical meningioma features. A wide immunohistochemical panel ruled out metastasis and endorsed the meningothelial nature of the lesion (positivity for epithelial membrane antigen and vimentin). Electron microscopy did not show usual hallmarks of meningioma but was helpful in excluding other tumors. Even though the three variants are associated with aggressive behavior, the patient is currently asymptomatic. The concurrent use of different techniques was essential for diagnosis.

Astroblastoma is a rare neuroepithelial neoplasm of unknown origin, usually occurring in children and young adults. Here we report a case of astroblastoma with uncommon features in an 18-year-old female. The tumor was a well-circumscribed cystic and solid mass with marked gadolinium enhancement in the right frontal lobe. Cytological examination showed polarized monopolar cells with diminished cohesiveness. Tumor cells possessed eccentric round to oval nuclei with abundant eosinophilic cytoplasm, sometimes having cytoplasmic processes. Histopathologically, the tumor showed perivascular pseudorosettes with prominent vascular sclerosis. Foam cells were frequently infiltrated around blood vessels and among tumor cells. In some areas, a solid growth pattern of plump tumor cells with abundant inclusion-like eosinophilic cytoplasm showing rhabdoid appearance was observed. The immunohistochemical study revealed strong and diffuse positivity for vimentin and epithelial membrane antigen. Tumor cells were focally positive for glial fibrillary acidic protein and cytokeratin AE1/AE3. Nuclear immunoreactivity for INI1 protein was evident. The Ki-67 labeling index was 10.8 %. This tumor was finally diagnosed as low-grade astroblastoma and the patient had no evidence of recurrence without postoperative radiotherapy or chemotherapy during the last 6 months of follow-up. This report describes novel cytological, histopathological, and immunohistochemical features of the rare tumor.

ᅟ Atypical teratoid/rhabdoid tumors are rare and highly malignant central nervous system tumors. They have no specific radiological features and often present several histological components that make a problem in differential diagnosis with medulloblastoma and primitive neuroectodermal tumors. We present the case of a newborn girl complained of a gradual proptosis of the left eye secondary to an expansive lesional process of the optic nerve. The location at the optic nerve, reported only twice in the literature, and an exclusive rhabdoid appearance on biopsy added additional differential diagnosis problems. The proptosis worsened and the infant died few days after two cycles of chemotherapy. Virtual slides The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2037718783145212.

Acantholytic variant of penile squamous cell carcinoma (SCC) is an exceedingly rare and associated with bad prognosis. Histologically it mimics angiosarcoma due to pseudovascular spaces. Vimentin immunopositivity in such cases represent epithelial to mesenchymal transition manifested by cellular discohesion. We describe a case of vimentin positive acantholytic penile SCC in a 55-year-old patient.

BACKGROUND: Rhabdoid meningioma exhibits high mitotic activity, anaplasia, and increased markers of cell proliferation. Here we describe a rhabdoid meningioma with a pattern of growth extending into the subarachnoid space and filled the cortical sulci. CASE DESCRIPTION: A 72-year-old woman presented with headache and was admitted to our hospital. Neurologic and physical examinations revealed no abnormalities. Contrast-enhanced axial T1-weighted images showed a well-enhanced, dural-based mass compressing the right temporal and frontal lobes, and extending into the sylvian cistern and filling the cortical sulci. The patient underwent partial resection and the histologic findings demonstrated rhabdoid meningioma. CONCLUSION: Although this type of tumor is known to be aggressive in its growth, extension into the adjacent cisternal space and the filling of the cortical sulci are rare. The combination of histologic anaplasia with the highest reported proliferation rate, loss of cohesion of neoplastic cells, and the location of the tumor led to the unique growth pattern.

Melanoma with rhabdoid features is an uncommon variant of malignant melanoma. Here, we describe a rare case of primary rhabdoid malignant melanoma. A 54-year-old man presented with a black tumor measuring 3×4 cm on the right forearm. Histologic sections showed a tumor mass with rhabdoid features composed entirely of polygonal neoplastic cells with eccentric nuclei, prominent nucleoli, and large hyaline cytoplasmic inclusions. The tumor cells were immunoreactive with HMB-45, S100, Fontana-Masson silver and vimentin, and negative for smooth muscle actin, CD68, CD34, CD99, synaptophysin, desmin, and PAS. The differential diagnosis for this tumor included malignant peripheral nerve sheath tumor, malignant peripheral neuroectodermal tumor and rhabdomyosarcoma. The patient was treated with a wide excision and a local skin graft. The excised tumor was entirely composed of rhabdoid tumor cells. No recurrence or metastasis was evident 4 months after removal. This article is relevant to rare cases of primary malignant melanomas showing rhabdoid tumor cells over the entire excised lesion.

Rhabdoid tumor, first described in kidneys of infants and children, is an aggressive tumor that has been reported in several extrarenal locations. In this report, we describe the case of a 40-year-old patient with gastric adenocarcinoma composed of histologically well-differentiated glandular areas and focal rhabdoid zones. The rhabdoid component showed typical features such as abundant eosinophilic cytoplasm, eccentric nuclei, prominent nucleoli and intense focal positive immunohistochemical cytoplasmic reaction for vimentin. Recognition of the rhabdoid phenotype in gastrointestinal tract neoplasms is important because this feature is associated with poor prognosis and unresponsiveness to conventional therapy.

Primary rhabdoid tumor of lung is a rare histological and clinical entity. Lung tumors with rhabdoid features have been included as variants of large-cell carcinoma in the 1999 World Health Organization (WHO) classification of lung tumors. A large-cell carcinoma with a rhabdoid phenotype (LCCRP) is unusual, with only 38 cases reported till date. We report the clinical details of one such case that was treated with pneumonectomy and adjuvant chemotherapy. We also present a review of the literature. To identify relevant articles, we searched PubMed, Ovid, and IngentaConnect databases using the key words ′rhabdoid,′ ′lung cancer,′ and ′primary rhabdoid tumor of lung.′