Extrarenal rhabdoid tumors of soft tissue: Clinicopathological and molecular genetic review and distinction from other soft-tissue sarcomas with rhabdoid features

Targeting epigenetic aberrations of sarcoma in CRISPR era

Sarcomas are rare malignancies that exhibit diverse biological, genetic, morphological, and clinical characteristics. Genetic alterations, such as gene fusions, mutations in transcriptional machinery components, histones, and DNA methylation regulatory molecules, play an essential role in sarcomagenesis. These mutations induce and/or cooperate with specific epigenetic aberrations required for the growth and maintenance of sarcomas. Appropriate mouse models have been developed to clarify the significance of genetic and epigenetic interactions in sarcomas. Studies using the mouse models for human sarcomas have demonstrated major advances in our understanding the developmental processes as well as tumor microenvironment of sarcomas. Recent technological progresses in epigenome editing will not only improve the studies using animal models but also provide a direct clue for epigenetic therapies. In this manuscript, we review important epigenetic aberrations in sarcomas and their representative mouse models, current methods of epigenetic editing using CRISPR/dCas9 systems, and potential applications in sarcoma studies and therapeutics.

CT and MR imaging features of soft tissue rhabdoid tumor: compared with rhabdomyosarcoma in children

Objective

To assess the computed tomography (CT) and magnetic resonance (MR) imaging characteristics of soft tissue rhabdoid tumors (RT) and compare them with those of rhabdomyosarcoma (RMS).

Methods

We conducted a retrospective analysis of 49 pediatric patients from 2011 to 2022, comprising 16 patients with soft tissue RT and 33 patients with RMS who underwent CT or MRI scans. Key imaging features, as well as clinical and pathological data, were compared between the two groups. The multivariate logistic regression analysis was used to determine independent differential factors for distinguishing soft tissue RT from RMS, and the model was established. The final prediction model was visualized by nomograms and verified internally by using a bootstrapped resample 1,000 times. The diagnostic accuracy of the combined model was assessed in terms of discrimination, calibration, and clinical utility.

Results

Age, sex, number of lesions, and primary locations were similar in both groups. The imaging characteristics, including margin, calcification, surrounding blood vessels, and rim enhancement, were associated with the two groups of soft tissue tumors, as determined by univariate analysis (all p < 0.05). On multivariate logistic regression analysis, the presence of unclear margin (p-value, adjusted odds ratio [95% confidence interval]: 0.03, 7.96 [1.23, 51.67]) and calcification (0.012, 30.37 [2.09, 440.70]) were independent differential factors for predicting soft tissue RT over RMS. The presence of rim enhancement (0.007, 0.05 [0.01, 0.43]) was an independent differential factor for predicting RMS over soft tissue RT. The comprehensive model established by logistic regression analysis showed an AUC of 0.872 with 81.8% specificity and 81.3% sensitivity. The decision curve analysis (DCA) curve displayed that the model achieved a better net clinical benefit.

Conclusion

Our study revealed that the image features of calcification, indistinct margins, and a lack of rim enhancement on CT and MRI might be reliable to distinguish soft tissue RT from RMS.

Extrarenal malignant rhabdoid tumor infiltrating the brachial plexus and spinal canal

Extrarenal malignant rhabdoid tumors are rare, aggressive lesions that primarily affect infants and children with characteristic SMARCB1/INI1 mutations. While rhabdoid tumors are most commonly found in the kidneys and central nervous system, they have been reported in virtually every soft tissue in the body. A 20-year-old previously healthy male presented with a 4-month history of left upper extremity weakness and pain and a 1-week history of lower extremity weakness. MRI showed a combined intradural and extradural mass arising from the C8 root and involving the lower trunk of the brachial plexus. CT guided biopsy followed with onsite cytologic analysis initially concerning for plasma cell etiology. Full body PET/CT showed no evidence of metastases. The tumor was surgically resected and debulked. Extensive immunohistochemical testing on the resected specimen revealed a diagnosis of extrarenal malignant rhabdoid tumor. Recurrence invading paraspinous muscles, left lateral paravertebral space, left apical lung, and brachial plexus was noted within 2 months. Radiation and chemotherapy were initiated. Here we present imaging findings, image-guided biopsy, surgical management, and pathologic diagnosis of a rare case of extrarenal, extracranial malignant rhabdoid tumor of the brachial plexus and surrounding paraspinous muscles in a young adult male.

Extrarenal rhabdoid tumour of axillary soft tissue: a diagnostic challenge resolved by immunohistochemistry

Extrarenal rhabdoid tumour of soft tissue in children is a rare tumour associated with poor prognosis. It is a heterogeneous group of aggressive tumours with distinct histopathological and immunohistochemistry findings. The tumour is characterised by diffuse proliferation of rhabdoid cells with hyaline like inclusion bodies. Defining feature is aberration of INI1/SMARCB1 gene located at chromosome 22q11.2. We report one such rare case in a female infant presenting as left axillary mass.

YM155 and chrysin cooperatively suppress survivin expression in SMARCB1/INI1-deficient tumor cells

SMARCB1/INI1 deficiency is seen in several malignant tumors including malignant rhabdoid tumor (MRT), a highly aggressive pediatric malignancy. Loss of SMARCB1/INI1 function alters diverse oncogenic cellular signals, making it difficult to discover effective targeting therapy. By utilizing an in vitro drug screening system, effective therapeutic agents against SMARCB1/INI1-deficient tumors were explored in this study. In the in vitro drug sensitivity test, 80 agents with various actions were screened for their cytotoxicity in a panel of five SMARCB1/INI1-deficient tumor cell lines. The combination effect was screened based on the Bliss independent model. The growth-inhibitory effect was determined in both the conventional two-dimensional culture and the collagen-embedded three-dimensional culture system. Survivin expression after agent exposure was determined by Western blot analysis. All five cell lines were found to be sensitive to YM155, a selective survivin inhibitor. In the drug combination screening, YM155 showed additive to synergistic effects with various agents including chrysin. Chrysin enhanced YM155-induced apoptosis, but not mitochondrial depolarization upon exposure of SMARCB1/INI1-deficient tumor cells to the two agents for 6 h. YM155 and chrysin synergistically suppressed survivin expression, especially in TTN45 cells in which such suppression was observed as early as 6 h after exposure to the two agents. Survivin is suggested to be a therapeutic target in MRT and other SMARCB1/INI1-deficient tumors. Chrysin, a flavone that is widely distributed in plants, cooperatively suppressed survivin expression and enhanced the cytotoxicity of YM155.

Establishment and characterization of NCC-MRT1-C1: a novel cell line of malignant rhabdoid tumor

Malignant rhabdoid tumor (MRT) is a sarcoma histologically characterized by rhabdoid cells and genetically characterized by loss of function of the chromatin remodeling complex SWI/SNF induced by SMARCB1 gene deficiency. MRT mainly occurs in children, may arise in various locations, but is predominantly in the central nervous system (CNS) and kidney. Although MRT exhibits poor prognosis, standard treatment has not yet been established due to its extreme rarity. Patient-derived cancer cell lines are critical tools for basic and pre-clinical research in the development of chemotherapy. However, none of the MRT cell lines was derived from adult patients, and only one cell line was derived from the MRT of a soft tissue, despite the clinical behavior of MRT varying according to patient age and anatomic site. Herein, we reported the first cell line of MRT isolated from the soft tissue of an adult patient and named it NCC-MRT1-C1. NCC-MRT1-C1 cells showed a biallelic loss of the SMARCB1 gene. NCC-MRT1-C1 cells demonstrated rapid proliferation, spheroid formation, invasion capability in vitro, and tumorigenesis in nude mice. Screening of antitumor agents in NCC-MRT1-C1 cells resulted in the identification of six effective drugs. In conclusion, we report the first MRT cell line from the soft tissue of an adult patient. We believe that NCC-MRT1-C1 is a useful tool for developing novel chemotherapies for MRT.

Update of pediatric soft tissue tumors with review of conventional MRI appearance-part 2: vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas

There are numerous soft tissue tumors and tumor-like conditions in the pediatric population. Magnetic resonance imaging is the most useful modality for imaging these lesions. Although certain soft tissue lesions exhibit magnetic resonance features characteristic of a specific diagnosis, most lesions are indeterminate, and a biopsy is necessary for diagnosis. We provide a detailed update of soft tissue tumors and tumor-like conditions that occur in the pediatric population, emphasizing each lesion's conventional magnetic resonance imaging appearance, using the recently released 5^th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors as a guide. In part one of this review, pediatric tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors are discussed. In part two, vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas are reviewed. Per the convention of the WHO, these lesions involve the connective, subcutaneous, and other non-parenchymatous organ soft tissues, as well as the peripheral and autonomic nervous system.

Primary adult sellar SMARCB1/INI1-deficient tumor represents a subtype of atypical teratoid/rhabdoid tumor

Loss of function in SMARCB1/INI1 has been observed in a group of malignancies collectively defined as SMARCB1/INI1-deficient neoplasms. Primary intracranial SMARCB1/INI1-deficient tumors in adults are extremely rare. We collected eight primary adult sellar SMARCB1/INI1-deficient tumors to study their clinicopathological and (epi)genetic characteristics. We performed a comprehensive assessment of the clinical, radiological, morphological and immunohistochemical features. FISH analysis for the SMARCB1 locus and target exome sequencing for 425 cancer relevant genes were performed. Furthermore, six bona fide proximal epithelioid sarcoma (PES), fourteen atypical teratoid/rhabdoid tumors (ATRT) in brain and five pediatric poorly differentiated chordomas (PDC) in the clivus were collected for comparative analysis of differential diagnostic maker expression and DNA methylation profile. The median age was 47.1 years, ranging from 26 to 73 years. On morphology, tumors were characterized by sheets of monomorphic larger epithelioid-like cells, in two cases with rhabdoid cells. "Stag-horn" vasculatures were observed in five cases. The loss of INI1 protein expression, co-expression of epithelial makers and mesenchymal markers were observed in all cases. CD34 expression was observed in six cases. Heterozygous deletion of SMARCB1/INI1 was confirmed using FISH in six cases. The results of target exome sequencing showed three patients harbored heterozygous point mutations in SMARCB1. The epigenetic features of the primary adult sellar SMARCB1/INI1-deficient tumors resembled the ATRT-MYC subgroup, but clustered apart from PES and PDC. Based on epigenetic characteristics, primary adult sellar SMARCB1/INI1-deficient tumors represent a subtype of ATRT with similar epigenetic characteristics of ATRT-MYC subgroup. Our findings suggest that DNA methylation profiling should be utilized for differential diagnosis for the majority of epithelioid sarcoma and (sellar) rhabdoid tumor.

Advances in the Diagnosis and Management of Neonatal Sarcomas

Neonatal sarcomas comprise a heterogeneous group of rare soft tissue neoplasms that present unique diagnostic and therapeutic challenges. Recent advances in molecular profiling have improved diagnostic capabilities and reveal novel therapeutic targets. Clinical trials demonstrate differences in behavior between sarcoma subtypes that allow for better clinical management. Surgical resection has been replaced with a multimodal approach that includes chemotherapy and radiotherapy. Despite these advances, neonates with sarcoma continue to fare worse than histologically similar sarcomas in older children, likely reflecting differences in tumor biology and the complexities of neonatal medicine. This review focuses on recent advances in managing neonatal sarcomas.

Functional dissection of the KRAS G12C mutation by comparison among multiple oncogenic driver mutations in a lung cancer cell line model

The development of molecular targeted therapy has improved clinical outcomes in patients with life-threatening advanced lung cancers with driver oncogenes. However, selective treatment for KRAS-mutant lung cancer remains underdeveloped. We have successfully characterised specific molecular and pathological features of KRAS-mutant lung cancer utilising newly developed cell line models that can elucidate the differences in driver oncogenes among tissues with identical genetic backgrounds. Among these KRAS-mutation-associated specific features, we focused on the IGF2-IGF1R pathway, which has been implicated in the drug resistance mechanisms to AMG 510, a recently developed selective inhibitor of KRAS G12C lung cancer. Experimental data derived from our cell line model can be used as a tool for clinical treatment strategy development through understanding of the biology of lung cancer. The model developed in this paper may help understand the mechanism of anticancer drug resistance in KRAS-mutated lung cancer and help develop new targeted therapies to treat patients with this disease.

Imaging Findings of a Malignant Rhabdoid Tumor in the Stomach: A Case Report

악성 횡문근양 종양은 주로 영유아의 신장에서 발생하는 공격적인 종양이다. 신장 이외의 조직에서 발생한 경우 신외성 악성 횡문근양 종양이라 하고 중추신경계, 간, 뇌, 피부, 연조직 등에서 드물게 보고되었다. 위에서 발생한 악성 횡문근양 종양은 매우 드물다. 저자들은 흑색변을 주소로 내원한 72세 남자의 위에서 발견된 악성 신외성 횡문근양 종양이 림프종과 유사한 영상 소견을 보인 예를 경험하여 보고한다.

SMARCB1/INI1-Deficient Extrarenal Rhabdoid Tumor: A Case Report of a Rare and Aggressive Soft Tissue Sarcoma

Malignant SMARCB1/INI1-deficient extrarenal rhabdoid tumors are aggressive tumors that are extremely rare in adults. A 56-year-old male presented with the chief complaints of unilateral lower abdominal and pelvic pain. He underwent urgent surgical intervention and mass resection with tissue sampling. After pathology confirmed the diagnosis, systemic chemotherapy with vincristine, doxorubicin plus ifosfamide, and mesna was administered. Following treatment, he experienced a durable and long-lasting response to therapy for this aggressive and rare soft tissue sarcoma. To date, the patient remains in complete remission following the cessation of chemotherapy. Malignant SMARCB1/INI1-deficient extrarenal rhabdoid tumors are aggressive neoplasms that are extremely rare in adults. We report a rare case of such a tumor and review the literature for its molecular, clinical, and imaging features.

Isolated Pure Malignant Rhabdoid Tumor (MRT) of the Bladder: Case Report and Lessons Learned

Pediatric extrarenal malignant rhabdoid tumors (MRTs) are rare, aggressive tumors with a poor prognosis (20% 5-year survival). There are currently fewer than 10 published case reports of primary MRT of the bladder. We report the case of an 18-month-old female with an isolated MRT of the bladder which was initially misdiagnosed as an inflammatory myofibroblastic tumor on biopsy. We review the history, tumor biology, histology, and current management of extrarenal MRT, along with lessons learned from the difficulty with the patient's initial diagnosis.

[Epithelioid, biphasic and mixed tumors of soft tissue]

Epithelioid soft tissue tumors consist exclusively of epithelioid tumor cells. Biphasic tumors are composed of both a spindle-cell and an epithelioid component. The rare mixed tumors of soft tissue show a broader variety of cellular and stromal differentiation but also include at least one, possibly several, epithelioid portions.The close morphological similarity of some of these entities with each other, as well as with the more frequent soft tissue metastases of carcinomas, carcinosarcomas, and melanomas, to malignant mesothelioma and certain lymphomas, can often make the correct diagnosis extremely difficult. Recent advances in the detection of certain molecular alterations (mostly chromosomal translocations) have contributed to changes in tumor classification but also to improved pathological diagnostics (e.g. through the development of potent diagnostic antibodies) and biological understanding.The present overview should help the pathologist in the diagnosis of these rare tumors through the classical approach of morphological pattern recognition. The most important entities are discussed and illustrated in more detail, with the incorporation of the latest immunohistochemical and molecular aspects and the differential diagnosis of similar tumors.

Malignant rhabdoid tumor of the musk gland and systemic T-cell lymphoma in a masked palm civet (Paguma larvata)

A 21-year-old male masked palm civet died after 2 months of continuous abdominal distention and poor appetite. Grossly, both musk glands were markedly swelled. Microscopically, round, polygonal and spindle neoplastic cells proliferated diffusely in the right musk gland and a metastatic focus was observed in the lung. The neoplastic cells had abundant cytoplasm with faintly eosinophilic inclusions that ultrastructurally corresponded to whorl aggregates of intermediate filaments. Immunohistochemically, these cells were positive for vimentin, cytokeratins and glial fibrillary acidic protein and negative for desmin. Based on these findings, the tumor was diagnosed as malignant rhabdoid tumor. Papillary adenoma was seen in the opposite musk gland. T-cell lymphoma of the lymph nodes, small intestine and liver was considered as the cause of death.

Proximal-type epithelioid sarcoma of the oral cavity: a case report and literature review

Proximal-type epithelioid sarcoma (PES) is an exceedingly rare malignant tumor of soft tissue; PES within the oral cavity is even rarer. Pathologic examination is the primary diagnostic modality, and surgical treatment is recommended as the preferred method for the treatment of PES. Currently, there is a paucity of literature that systematically reports on PES in the oral cavity. Here, we describe a 42-year-old man with PES in the oral cavity, which showed positivity for vimentin, cytokeratin, CD31, S-100 but did not express BCL-2, HMB-45, or desmin. We performed a wide excision and neck dissection, and then used the free anterolateral thigh flap to reconstruct the defect in the soft tissue. Furthermore, we review the current literature with regard to diagnosis and treatment of PES.

SMARCB1/INI1/BAF47- deficient pleural malignant mesothelioma with rhabdoid features

Malignant mesothelioma (MM) with rhabdoid features is an MM variant. Fifteen cases have been reported previously, all of which were combined with other types of MM. Herein, we report an autopsy case of pleural MM with monomorphic rhabdoid features. The patient was a 62-year-old male without a history of asbestos exposure. An autopsy revealed a soft, granular tumor that replaced the entire left pleura and had invaded to the diaphragm and lower lobe of the lung. The tumor cells, which had eosinophilic plump cytoplasm and eccentric nuclei, were loosely cohesive. Immunohistochemistry showed that the cells were diffusely positive for calretinin, D2-40, vimentin, CAM5.2, and AE1/AE3; and negative for WT-1, TTF-1, CK7, CEA, desmin, CD34, BCL-2, S100 protein, and p40. Neither homozygous deletion of p16 nor BAP-1 protein loss was observed. Loss of INI1/BAF47 protein, an indicator of malignant rhabdoid tumor, was observed. Therefore, MM with rhabdoid features was confirmed.

Intradural lumbosacral malignant extrarenal rhabdoid tumor: a case report

BACKGROUND

Rhabdoid tumors are highly malignant tumors predominantly affecting the pediatric population. When these tumors occur outside of the kidneys, they are referred to as malignant extrarenal rhabdoid tumors (MERT), a rare highly aggressive subtype. Less commonly, these tumors involve the neuro-axis.

OBJECTIVE

Here we present a case of a 15-year-old girl with intradural MERT of the lumbosacral spine who presented with back pain, sudden worsening of lower extremity strength, and complete loss of bowel and bladder control.

RESULTS

The patient's tumor showed loss of INI-1 and negative staining for cytokeratin AE1AE3, CD99, and SOX10.

CONCLUSIONS

To our knowledge, there are no previous case reports of MERT with intradural lumbosacral spinal involvement.

Extrarenal rhabdoid tumor presented with an immobile arm in a one-year-old boy

Infants with an immobile arm may be easily overlooked in primary care settings. Differential diagnoses include injuries, infections, neuropathies, ischemia and rarely, neoplasms. We report the case of a one-year-old boy with weakness in his left arm after minor trauma with a diagnosis of brachial plexus palsy initially. After rehabilitation for 2months, his weakness progressed to unsteady gait and quadriparesis. MRI revealed a huge solid tumor in the left supraclavicular fossa, which also involved the left brachial plexus, upper thoracic cavity, and left paravertebral space with invasion into the spinal canal. Microscopically, the medium-large polygonal tumor cells had an eccentric eosinophilic cytoplasm and immunostaining showed a loss of nuclear INI1 expression. Array comparative genomic hybridization of the tumor tissue confirmed a segmental deletion at chromosome region 22q11.23 involving the SMARCB1 gene. The final diagnosis was cervical paravertebral malignant rhabdoid tumor with intraspinal epidural and intradural invasion, a rare case of extrarenal extracranial rhabdoid tumor (ERRT). The intraspinal part of the tumor was resected followed by interval-compressed chemotherapy with vincristine-doxorubicin-cyclophosphamide alternating with ifosfamide-etoposide (VDC/IE). The tumor showed very good partial response to four cycles of chemotherapy with gradual recovery of neurological symptoms. ERRT is a very rare and aggressive tumor that mainly occurs in infants and children and may manifest with vague neurological symptoms when it involves the spinal cord and/or peripheral nerves. A neoplasm such as ERRT originating from or involving the brachial plexus should be considered in the differential diagnosis of an immobile arm in infancy.

INI Expressing Epithelioid Sarcoma with Osteoclastic Giant Cells in a Child: A Case Report with Summary of Prior Published Cases

BACKGROUND

Epithelioid sarcoma is a heterogeneous tumor with 2 subtypes, classic and proximal. The proximal variant is more aggressive and occurs in proximal location in young adults.

CASE REPORT

We present a proximal epithelioid sarcoma in the leg of an 8 year old girl with rhabdoid morphology and scattered osteoclastic giant cells. Nuclear INI-1 was retained. Despite wide local excision, local recurrence occurred at 8 months. Following re-excision, she developed a chest wall metastasis after 9 months.

CONCLUSION

Epithelioid sarcoma, proximal type with osteoclastic giant cells in the pediatric age group has not been reported previously and should be considered in the differential diagnoses of tumors with epithelioid cell morphology and scattered osteoclastic giant cells. Retained INI expression helped to differentiate this tumor from malignant rhabdoid tumor.

Primary Osteosarcoma of the Bone with Rhabdoid Features: A Rare, Previously Undescribed Primary Malignant Tumor of Bone

Primary osteosarcoma of the bone with rhabdoid features is a rare malignant tumor of bone, not previously described in the literature. Here we report a 69-year-old female who originally presented with a right femur pathologic fracture. Radiographs of the injury showed an aggressive-appearing lesion of the distal femur. Initial biopsy was done, which was not diagnostic; additional advanced imaging studies were performed, which failed to show any other site within the body with detectable disease process. Accordingly, the patient underwent radical resection of the distal femur and reconstruction with endoprosthesis. Histopathology obtained from the operative specimen showed osteosarcoma with rhabdoid features. Two months after surgery, the patient is symptom-free and doing well; she is currently pending adjuvant chemotherapy. Although rhabdoid features have been described in extraskeletal osteosarcoma, this appears to be the first mention of osteosarcoma of bone with rhabdoid features in the literature.

The molecular pathogenesis of schwannomatosis, a paradigm for the co-involvement of multiple tumour suppressor genes in tumorigenesis

Schwannomatosis is characterized by the predisposition to develop multiple schwannomas and, less commonly, meningiomas. Despite the clinical overlap with neurofibromatosis type 2 (NF2), schwannomatosis is not caused by germline NF2 gene mutations. Instead, germline mutations of either the SMARCB1 or LZTR1 tumour suppressor genes have been identified in 86% of familial and 40% of sporadic schwannomatosis patients. In contrast to patients with rhabdoid tumours, which are due to complete loss-of-function SMARCB1 mutations, individuals with schwannomatosis harbour predominantly hypomorphic SMARCB1 mutations which give rise to the synthesis of mutant proteins with residual function that do not cause rhabdoid tumours. Although biallelic mutations of SMARCB1 or LZTR1 have been detected in the tumours of patients with schwannomatosis, the classical two-hit model of tumorigenesis is insufficient to account for schwannoma growth, since NF2 is also frequently inactivated in these tumours. Consequently, tumorigenesis in schwannomatosis must involve the mutation of at least two different tumour suppressor genes, an occurrence frequently mediated by loss of heterozygosity of large parts of chromosome 22q harbouring not only SMARCB1 and LZTR1 but also NF2. Thus, schwannomatosis is paradigmatic for a tumour predisposition syndrome caused by the concomitant mutational inactivation of two or more tumour suppressor genes. This review provides an overview of current models of tumorigenesis and mutational patterns underlying schwannomatosis that will ultimately help to explain the complex clinical presentation of this rare disease.

Reclassification of rhabdoid tumor and pediatric undifferentiated/unclassified sarcoma with complete loss of SMARCB1/INI1 protein expression: three subtypes of rhabdoid tumor according to their histological features

Rhabdoid tumor is characterized by rhabdoid cells and shows complete loss of SMARCB1/INI1 protein expression. In existing classifications, the diagnostic synonyms vary depending on the anatomic site: rhabdoid tumors in the central nervous system or extra-central nervous system are, respectively, classified as atypical teratoid/rhabdoid tumor or malignant rhabdoid tumor. In this study, we analyzed the histological, immunohistochemical, microRNA, and clinicopathological statuses of tumors initially diagnosed as malignant rhabdoid tumor (n=33), atypical teratoid/rhabdoid tumor (n=11), and pediatric undifferentiated/unclassified sarcoma (n=8) with complete loss of SMARCB1/INI1 expression, and considered the possibility of their histological reclassification. Our analysis indicated that the tumors could be histologically reclassified into three groups: conventional-type tumors resembling malignant rhabdoid tumor, atypical teratoid/rhabdoid-type tumors resembling atypical teratoid/rhabdoid tumor, and small cell-type tumors resembling malignant lymphoma. The reclassified conventional type was composed of 27 malignant rhabdoid tumors and 9 atypical teratoid/rhabdoid tumors (36 cases). The atypical teratoid/rhabdoid type consisted of six malignant rhabdoid tumors, two atypical teratoid/rhabdoid tumors, and two undifferentiated/unclassified sarcomas (10 cases). The six cases of small cell type were made up of six undifferentiated/unclassified sarcomas. All of the available tumor specimens were positive for vimentin and epithelial marker (EMA, CAM5.2, or AE1/AE3). MicroRNA profiles were not significantly different between the conventional- and small cell-type tumors (Pearson's correlation coefficient: 0.888300 or 0.891388). There was no significant difference in overall survival between atypical teratoid/rhabdoid tumor and malignant rhabdoid tumor (P=0.16). In addition, there were no significant differences in survival between any of the reclassified combinations. In conclusion, we could classify eight tumors initially diagnosed as undifferentiated/unclassified sarcomas into two cases of atypical teratoid/rhabdoid type and six cases of small cell type. We suggest that reclassification of malignant rhabdoid tumors into three groups according to their histologic features rather than the traditional classification by sites of origin would be favorable for their histopathological diagnosis.

Disseminated Malignant Rhabdoid Tumor of the Head and Neck

Disseminated extrarenal malignant rhabdoid tumors of the head and neck are very rare, but aggressive tumors. Although the features on radiological imaging may be nonspecific, the imaging is useful for assessing the extent of tumor involvement. Key pathologic features are those of a cellular "blue cell tumor" with variable rhabdoid appearance. These cells express a combination of markers usually viewed as characteristic of diverse lines of differentiation, including EMA, cytokeratins, smooth muscle markers, and GFAP, and occasionally synaptophysin. At a molecular level, the entity is defined by mutations or alterations in the SMARB1/INI1 gene resulting in loss of INI1 expression. Diagnostic features include rhabdoid cells, expression of keratin with absence of desmin, S100 protein and CD34, and loss of INI1 expression. These features are exemplified in this sine qua non radiology-pathology correlation article.

Management of Anesthesia in a Child with a Large Neck Rhabdoid Tumor

OBJECTIVE

The aim of this paper was to report the management of anesthesia of a child with a large neck rhabdoid tumor.

CLINICAL PRESENTATION AND INTERVENTION

A 9-month- old female patient underwent urgent neck tumor excision due to intratumoral bleeding from a large tumor that compressed and dislocated the trachea; therefore, intubation was expected to be difficult. Sevoflurane inhalation induction was utilized to maintain spontaneous respiration. Oral laryngoscopy revealed Cormack-Lehane grade 3 laryngeal view. The trachea was intubated using a reinforced tube on the third attempt. Fiberoptic bronchoscope-assisted intubation was planned as an alternative in case of conventional intubation failure. Anticipation of massive blood loss necessitated central venous catheterization.

CONCLUSION

Establishing a safe airway, intubation during spontaneous breathing and invasive hemodynamic monitoring are crucial factors in the anesthetic management of pediatric patients with a large neck tumor.

Regulated lysosomal exocytosis mediates cancer progression

Understanding how tumor cells transition to an invasive and drug-resistant phenotype is central to cancer biology, but the mechanisms underlying this transition remain unclear. We show that sarcomas gain these malignant traits by inducing lysosomal exocytosis, a ubiquitous physiological process. During lysosomal exocytosis, the movement of exocytic lysosomes along the cytoskeleton and their docking at the plasma membrane involve LAMP1, a sialylated membrane glycoprotein and target of the sialidase NEU1. Cleavage of LAMP1 sialic acids by NEU1 limits the extent of lysosomal exocytosis. We found that by down-regulation of NEU1 and accumulation of oversialylated LAMP1, tumor cells exacerbate lysosomal exocytosis of soluble hydrolases and exosomes. This facilitates matrix invasion and propagation of invasive signals, and purging of lysosomotropic chemotherapeutics. In Arf (-⁄-) mice, Neu1 haploinsufficiency fostered the development of invasive, pleomorphic sarcomas, expressing epithelial and mesenchymal markers, and lysosomal exocytosis effectors, LAMP1 and Myosin-11. These features are analogous to those of metastatic, pleomorphic human sarcomas, where low NEU1 levels correlate with high expression of lysosomal exocytosis markers. In a therapeutic proof of principle, we demonstrate that inhibiting lysosomal exocytosis reversed invasiveness and chemoresistance in aggressive sarcoma cells. Thus, we reveal that this unconventional, lysosome-regulated pathway plays a primary role in tumor progression and chemoresistance.

Vulvar sarcomas: Short guideline for histopathological recognition and clinical management. Part 1

Malignant tumors of the female reproductive system are a serious health and social problem, as they are the second most common cause of death among women, after breast cancer. Their incidence has increased dramatically during recent years, probably due to the different sexual habits and changes in the prevalence of HIV/ AIDS and HPV virus carriers, among other factors. Vulvar tumors represent only 4% of all gynecological neoplasms, and they are fourth in frequency after tumors of the cervix, uterus, and ovary. Ninety eight percent of all vulvar tumors are benign and only 2% are malignant. The overall incidence of tumors with vulvar location is between two and seven cases per 100,000 women, and it increases with age, while the death rate is estimated at 0.7 per 100,000 women. Sarcomas of the vulva comprise approximately 1-3% of all vulvar cancers, with leiomyosarcomas, epithelioid sarcomas, and rhabdomyosarcomas being the most common among them. They are characterized by rapid growth, high metastatic potential, frequent recurrences, aggressive behavior, and high mortality rate. In this paper, we present the most common forms of sarcomas of the vulva (leiomyosarcoma, epithelioid sarcoma, malignant rhabdoid tumor, rhabdomyosarcoma) in order to emphasize the broad differential diagnosis, rare appearance, non-specific clinical picture, aggressive course, and high mortality.

A rapid progression of disease after surgical excision of a malignant rhabdoid tumor of the bladder

Extrarenal malignant rhabdoid tumors (MRTs) are rare tumors with a poor prognosis. Five-year overall survival for patients with MRTs is poor at approximately 20%.(1) There are 5 case reports of histologically confirmed primary MRT of the bladder in pediatric patients. Herein, we report a case of an MRT of the bladder in a 14-year-old boy and discuss the preoperative evaluation, treatment options, and possible etiologies of metastasis after radical surgery.

Extra-cranial Malignant Rhabdoid Tumor in Children: A Single Institute Experience

Purpose

Malignant rhabdoid tumor (MRT) is a rare and highly aggressive tumor that affects young children. Due to its extreme rarity, most of the available data are based on retrospective case series. To add to the current knowledge of this disease, we reviewed the patients treated for extra-cranial MRT in our institute.

Materials and Methods

A retrospective medical record review was conducted on children treated for pathologically confirmed extra-cranial MRT at Seoul National University Children’s Hospital between January 2003 and May 2013.

Results

Eleven patients (7 boys, 4 girls) were diagnosed with extra-cranial MRT at a median age of 9 months old. INI1 staining was important in the pathological confirmation. Six patients (55%) had renal MRT and five (45%) had soft tissue MRT. Five patients (45%) had metastases at diagnosis. All patients underwent chemotherapy, eight patients (73%) underwent surgery, six patients (55%) received therapeutic radiotherapy, and four patients (36%) underwent high dose chemotherapy with autologous stem cell rescue (HDCT/ASCR) with melphalan, etoposide, and carboplatin. Five patients (45%) died of disease following progression (n=3) or relapse (n=2), however, there was no treatment related mortality. The overall survival of the cohort was 53.0% and the event-free survival was 54.5% with a median follow-up duration of 17.8 months (range, 2.3 to 112.3 months).

Conclusion

Extra-cranial MRT is still a highly aggressive tumor in young children. However, the improved survival of our cohort is promising and HDCT/ASCR with melphalan, etoposide, and carboplatin may be a promising treatment option.

Malignant Rhabdoid Tumor with Cervical Vertebra Involvement in a Teenage Child: Case Report and Review of the Literature

Malignant rhabdoid tumor (MRT) is a highly malignant and aggressive tumor associated with the kidney that is mainly seen in children under 5 years old, resulting in a rapid fatal outcome. MRT invasion of the cervical vertebra is an extremely rare form of this malignancy. This study presents a case of MRT involving the C4 vertebra and its appendix. A 13-year-old girl was found to have vague neck pain and a mass in the left neck area of the mid-cervical spine. Percutaneous needle biopsy was performed and the histological and immunohistochemical analysis pointed towards a rhabdoid tumor. Chemotherapy and radiotherapy were performed, but the tumor mass progressively enlarged. Tumorectomy was conducted followed by another 6 courses of chemotherapy and (125)I radioactive seed implantation. Unfortunately, the C4 vertebra and its appendix were found to be abnormal 3 months after the end of therapy. The patient received an additional tumorectomy, internal fixation with C4 reconstruction by a combined anterior and posterior approach, and 6 courses of consolidation chemotherapy. She is still alive 40 months since the initial diagnosis and remains asymptomatic 31 months after the surgery.

Good response to chemotherapy spares irradiation for extrarenal rhabdoid tumor conferring better activities of daily living

A 7-year-old girl with stage IIA extrarenal rhabdoid tumor near the left cubital fossa received preoperative chemotherapy and surgical resection with median nerve reconstruction followed by postoperative high-dose chemotherapy. As preoperative chemotherapy resulted in decreased tumor size, disappearance of fluorodeoxyglucose-uptake, and pathologic complete response with total tumor resection, irradiation was successfully spared to avoid injury to the reconstructed nerve and inhibition of normal bone development. Two years after diagnosis, recurrence has not been observed and median nerve palsy is improving. This case suggests that radiation therapy could be spared for clinically and pathologically chemotherapy-good-responders in case total surgical resection is achieved.

Magnetic Resonance Imaging Features of Rhabdoid Glioblastomas

PURPOSE

Rhabdoid glioblastoma (rGB) is a recently described, highly aggressive brain tumor, in which glioblastoma (GB) is associated with a rhabdoid component. So far only 21 cases have been reported and its imaging findings have not been studied in detail. In this paper, we present 11 additional cases and aim to depict detailed magnetic resonance imaging (MRI) features of this tumor in comparison with the previous cases of rGBs and our cohort of typical GBs.

METHODS

Retrospective evaluation of the glass slides of 249 GB patients disclosed 14 cases with rhabdoid morphology. Eleven of these cases with available MRI were included in the study. Immunohistochemistry was also performed. MRI and clinicopathologic findings were compared with those of previous rGBs and typical GBs.

RESULTS

(1) rGB is usually a large, well-delineated solid tumor with extensive necrosis, heterogeneous contrast enhancement, occasional hemorrhage, and cysts, (2) rGB may present at an older age than previously reported, but still in younger individuals compared with typical GB patients, (3) tumor dissemination in the form of leptomeningeal seeding and more rarely extracranial metastases is a feature of rGBs, although leptomeningeal seeding may not be as high as previously reported, (4) prognosis is poor in rGBs.

CONCLUSIONS

rGB is a new entity which has not yet appeared in the WHO classification of central nervous system (CNS) tumors. Understanding its clinical and imaging features may help to distinguish it from other tumors of CNS.

MicroRNA signatures as biomarkers and therapeutic target for CNS embryonal tumors: the pros and the cons

Embryonal tumors of the central nervous system represent a heterogeneous group of childhood cancers with an unknown pathogenesis; diagnosis, on the basis of histological appearance alone, is controversial and patients’ response to therapy is difficult to predict. They encompass medulloblastoma, atypical teratoid/rhabdoid tumors and a group of primitive neuroectodermal tumors. All are aggressive tumors with the tendency to disseminate throughout the central nervous system. The large amount of genomic and molecular data generated over the last 5–10 years encourages optimism that new molecular targets will soon improve outcomes. Recent neurobiological studies have uncovered the key role of microRNAs (miRNAs) in embryonal tumors biology and their potential use as biomarkers is increasingly being recognized and investigated. However the successful use of microRNAs as reliable biomarkers for the detection and management of pediatric brain tumors represents a substantial challenge. This review debates the importance of miRNAs in the biology of central nervous systemembryonal tumors focusing on medulloblastoma and atypical teratoid/rhabdoid tumors and highlights the advantages as well as the limitations of their prospective application as biomarkers and candidates for molecular therapeutic targets.

Clinicopathological characteristics of anaplastic carcinoma of the pancreas with rhabdoid features

Undifferentiated (anaplastic) carcinoma with rhabdoid features is a rare and aggressive subtype of pancreatic carcinoma. Here, we report the clinical, histological, and immunohistochemical phenotypes in six autopsy cases of anaplastic carcinoma with rhabdoid features. The patients ranged between 44 and 76 years of age (median, 61 years) and consisted of four males and two females. All patients except one case died within 3 months of diagnosis, as these tumors were found at an advanced stage and were chemoresistant. At autopsy, tumor masses measuring 4-22 cm in maximum diameter were mainly located in the pancreatic body and tail. Microscopically, all cases showed anaplastic carcinoma with rhabdoid features that were discohesive with round to polygonal eosinophilic cytoplasm with occasional inclusions, and that had vesicular nuclei, and prominent nucleoli. Immunohistochemistry showed that the rhabdoid cells, particularly the inclusions, were strongly positive for pan-cytokeratin (AE1/AE3) and vimentin. Meanwhile, downregulation or aberrant cytoplasmic localization with focal aggregation of E-cadherin, β-catenin, and EMA were frequently observed in the rhabdoid cells. Moreover, the intracytoplasmic inclusions were labeled with selective autophagy-related molecules including p62/SQSTM1, ubiquitin, and kelch-like ECH-associated protein 1 (KEAP1). In addition, nuclear factor erythroid 2-related factor 2 (NRF2) and overexpression of its target molecule multidrug resistance-associated protein 1 (MRP1) were commonly observed in the rhabdoid cells. Therefore, these results suggest that p62-mediated aggregation of ubiquitinated intermediate filaments and membranous proteins is an important phenomenon in the rhabdoid phenotype. Indeed, the ubiquitinated aggregates of p62 and KEAP1 would induce activation of NRF2 and upregulation of MRP1, leading to potential chemoresistance of anaplastic carcinoma with rhabdoid features.

Subcutaneous soft tissue sarcoma with rhabdoid features in a dog

A nine-year-old male beagle dog had a white spherical mass in the subcutis of the left lumbar region. Microscopically, spindle to oval cells diffusely proliferated in the fibrous and myxoid stroma. Many neoplastic cells showed rhabdoid features or vacuolated cytoplasm. Immunohistochemically, the neoplastic cells were positive for vimentin and S100 and partly positive for neuron-specific enolase and glial fibrillary acidic protein but were negative for von Willebrand factor, desmin and α-smooth muscle actin. Ultrastructurally, the neoplastic cells had abundant cytoplasmic processes and desmosome-like structures. Cytoplasmic inclusions of rhabdoid-featured cells in HE sections were composed of aggregates of intermediate filaments, and cytoplasmic vacuoles were identified as an invagination of cytoplasm. Although malignant peripheral nerve sheath tumor was suggested according to these results, the present case was diagnosed as a soft tissue sarcoma with rhabdoid features due to a lack of identification of the basal lamina under electron microscopy.

Malignant rhabdoid tumor of the tongue: A rare occurrence

Malignant rhabdoid tumors (MRTs) are highly aggressive neoplasms that most commonly occur in the kidneys of young children. Malignant rhabdoid tumor of the tongue is an extremely rare entity and very few have been reported in the literature. The course of extra-renal MRT is short and its prognosis is very poor. A 19-year-old female presented with a progressive swelling and restricted mobility of the tongue for over 3 months duration. We present here a locally advanced case of MRT of the tongue, its diagnosis, management and review of the literature related to it.

Malignant extra renal rhabdoid tumour presenting as central airway obstruction

Rhabdoid tumours are one of the most aggressive childhood neoplasms associated with high mortality. The commonest age group affected is children less than five years of age. Rhabdoid tumour presenting as an endoluminal tracheal mass leading to central airway obstruction has not been previously reported. We describe the case of a 17-year-old male patient where malignant rhabdoid tumour masqueraded as bronchial asthma leading to a delayed diagnosis of upper airway obstruction by tracheal growth. Histopathological examination and immunohistochemistry confirmed the diagnosis of malignant rhabdoid tumour.

Cutaneous Pleomorphic Rhabdomyosarcoma Occurring on Sun-Damaged Skin: A Case Report

Rhabdomyosarcoma (RMS) is a malignant soft tissue tumor with skeletal muscle differentiation that can rarely present as a primary cutaneous tumor. There are 3 main subtypes of RMS: embryonal, alveolar, and pleomorphic. Primary cutaneous pleomorphic RMS is extremely rare, there being only 9 reported cases in the literature, 2 of which are radiation induced. We present a case of primary pleomorphic RMS occurring on the sun-damaged skin of the face of an 89-year-old woman. The tumor was diagnosed by histology, immunohistochemistry, and electron microscopy. The patient was treated by surgery and adjuvant radiotherapy. The tumor recurred rapidly after surgical excision. She died 2 months after the diagnosis from complications of treatment, local symptoms of tumor, and concurrent illnesses. Primary cutaneous pleomorphic RMS is a rare tumor of adults and pursues an aggressive clinical course.

Malignant rhabdoid tumor of the floor of mouth: first reported case in the oral cavity of an adult

Malignant rhabdoid tumors (MRTs) are exceedingly rare lesions. To our knowledge, only 2 cases have been reported in the oral cavity, with both examples occurring in infants. The current case is the third reported case of MRT of the oral cavity and the first reported case to occur in an adult at this location. The following report describes the clinical, histologic and immunohistochemical features of this tumor.

Primary sinonasal mucosal melanoma with aberrant diffuse and strong desmin reactivity: a potential diagnostic pitfall!

The broad morphologic spectrum, inherent immunophenotypic heterogeneity of malignant melanoma and its rarity in the sinonasal tract are major challenges in eliciting the correct diagnosis, which may lead to misclassification and inadequate medical management. Herein, we describe a single case of a 70 year-old male with sinonasal mucosal melanoma, exhibiting varying histologic phenotypes including small round blue cell morphology, epithelioid and focal rhabdoid morphology and strong, diffuse desmin immunoreactivity. These constellation of features initially prompted the diagnosis of rhabdomyosarcoma. The differential diagnosis in this anatomic area includes other malignant small round blue cell tumors of the sinonasal mucosa such as rhabdomyosarcoma, olfactory neuroblastoma, sinonasal undifferentiated carcinoma, and lymphoma. We reviewed precedent literature and further discuss the potential pitfalls to which pathologists may be prone.