Histopathological, immunohistochemical and molecular cytogenetic analysis of 21 spindle cell/sclerosing rhabdomyosarcomas

Tongue Spindle Cell Rhabdomyosarcoma: A Rare Case Report and Literature Review

Rhabdomyosarcoma (RMS) is a malignant soft tissue neoplasm with its origin in the skeletal muscle and is extremely rare in adults. By the World Health Organization (WHO), a new variant of RMS has been classified, i.e. the spindle cell (Sc) and sclerosing (S) RMS. While the Sc-RMS shows intersecting fascicles of nonpleomorphic spindle cells, the S-RMS is characterized by a marked hyalinization in a pseudovascular growth pattern associated with round-to-spindled tumour cells. According to the analysed data, the Sc/S-RMS variant has a worse outcome than other variants. The new classification of the Sc/S-RMS variant is valuable to the clinical practice. There are not many oral Sc/S-RMS cases reported. The aim of this paper is to demonstrate that an early diagnosis, an adequate treatment and a multidisciplinary approach have a positive effect on the prognosis of the patient. In this study, we analyse a new case of Sc-RMS variant in a young adult with an early diagnosis and a favourable outcome as a result of an appropriated multidisciplinary treatment: early surgery, radiotherapy and chemotherapy treatment.

Establishment and characterization of NCC-ssRMS2-C1: a novel patient-derived cell line of spindle cell/sclerosing rhabdomyosarcoma

Spindle cell/sclerosing rhabdomyosarcoma (ssRMS) is a rare subtype of rhabdomyosarcoma (RMS) that has fascicular spindle cell and/or sclerosing morphology. SsRMS has a diverse molecular background and is categorized into three groups: congenital/infantile ssRMS with a gene fusion involving the NCOA2 and VGLL2, ssRMS with the MYOD1 mutation, and ssRMS with no recurrent identifiable genetic alterations. Because ssRMS is a newly defined disease concept of RMS, the optimal treatment methods have not been determined. This results in unfavorable prognosis and consequently signals the urgent need for continuous research. Patient-derived cell lines are essential tools in basic and translational research. However, only two ssRMS cell lines with the MYOD1 mutation have been reported to date. Thus, we established a novel ssRMS cell line named NCC-ssRMS2-C1 using a surgically resected tumor tissue from an adult ssRMS patient. NCC-ssRMS2-C1 cells retained the copy number alterations corresponding to the original tumor and are categorized into the group with no recurrent identifiable genetic alterations. NCC-ssRMS2-C1 cells demonstrated constant proliferation, spheroid formation, and capability for invasion in vitro, reflecting the malignant features of the original tumor tissue. In a drug screening test, ssRMS demonstrated remarkable sensitivity to romidepsin, trabectedin, actinomycin D, and bortezomib. Hence, we conclude that the NCC-ssRMS2-C1 cell line is the first ssRMS cell line which belongs to the group with no recurrent identifiable genetic alterations, and it will be a useful resource in both basic and translational studies for ssRMS.

Establishment and Characterization of a Sclerosing Spindle Cell Rhabdomyosarcoma Cell Line with a Complex Genomic Profile

Sclerosing spindle cell rhabdomyosarcoma (SSRMS) is a rare rhabdomyosarcomas (RMS) subtype. Especially cases bearing a myogenic differentiation 1 (MYOD1) mutation are characterized by a high recurrence and metastasis rate, often leading to a fatal outcome. SSRMS cell lines are valuable in vitro models for studying disease mechanisms and for the preclinical evaluation of new therapeutic approaches. In this study, a cell line established from a primary SSRMS tumor of a 24-year-old female after multimodal chemotherapeutic pretreatment has been characterized in detail, including immunohistochemistry, growth characteristics, cytogenetic analysis, mutation analysis, evaluation of stem cell marker expression, differentiation potential, and tumorigenicity in mice. The cell line which was designated SRH exhibited a complex genomic profile, including several translocations and deletions. Array-comparative genomic hybridization (CGH) revealed an overall predominating loss of gene loci. The mesenchymal tumor origin was underlined by the expression of mesenchymal markers and potential to undergo adipogenic and osteogenic differentiation. Despite myogenic marker expression, terminal myogenic differentiation was inhibited, which might be elicited by the MYOD1 hotspot mutation. In vivo tumorigenicity could be confirmed after subcutaneous injection into NOD/SCID/γ_c^null mice. Summarized, the SRH cell line is the first adult SSRMS cell line available for preclinical research on this rare RMS subtype.

Therapeutic outcome and prognostic factors in sinonasal rhabdomyosarcoma: a single-institution case series

BACKGROUND

The purpose of this study was to explore the demographics, multimodality therapeutic outcomes*** and prognostic factors in sinonasal rhabdomyosarcoma (SNRMS).

METHODS

We conducted a retrospective analysis of 40 patients who underwent treatment of SNRMS from March 2007 to March 2018. The Kaplan-Meier method and the log-rank test were used to assess survival rates. The Cox regression model was used for multivariate survival analysis.

RESULTS

In total, 25 males and 15 females were included in the study; the median age was 33 years (range, 2-67 years). All patients underwent surgical resection, and surgery prior to or after adjuvant therapy (chemotherapy and radiotherapy) was performed in 91.4% of the patients. The overall 1-, 3- and 5-year survival rates were 77.0%, 46.5% and 46.5%, respectively, during a mean follow-up time of 27.9 (range, 2-128) months in all patients. The log-rank test showed Intergroup Rhabdomyosarcoma Study (IRS) group and infiltration of the skull base influenced overall survival (p = 0.001; p = 0.022). Advanced IRS stage, lymph node metastasis and tumor size ≥ 5 cm were also associated with an unfavorable outcome on overall survival (p = 0.01; p = 0.035; p = 0.02). The results of multivariate regression analysis showed patients with IRS group I were associated with better prognosis outcome on overall survival.

CONCLUSION

Patients with SNRMS have poor 5-year overall survival, and IRS group is the independent prognostic factor for overall survival.

Ear and Temporal Bone Pathology: Neural, Sclerosing and Myofibroblastic Lesions

Neural, sclerosing, and myofibroblastic lesions of the ear and temporal bone present diagnostic challenges for both clinicians and pathologists due to significant overlap in their clinical presentations, histologic appearances, and immunohistochemical profiles. While some of these lesions, such as schwannomas, are relatively common, others are rendered even more difficult because they are encountered very rarely in routine surgical pathology practice. This review is intended to provide an update on the pathology of some of the most commonly encountered primary diagnostic entities for the ear and temporal bone, and includes the following neural lesions: schwannoma, meningioma, and encephalocele/meningocele. Sclerosing lesions that will be discussed include spindle cell and sclerosing rhabdomyosarcoma, sclerosing epithelioid fibrosarcoma, and sclerosing paraganglioma. Finally, myofibroblastic lesions that will be reviewed are nodular fasciitis, IgG4-related disease, and solitary fibrous tumor. For each of these lesions, the differential diagnosis and useful ancillary tests will be discussed in the context of a broad range of additional primary and secondary lesions.

Spindle cell/sclerosing rhabdomyosarcoma with intracranial invasion without destroying the bone of the skull base: a case report and literature review

Spindle cell/sclerosing rhabdomyosarcoma (ssRMS) is a new subtype of rhabdomyosarcoma included in the World Health Organization soft tissue and bone tumor classification in 2013. Despite the increasing number of reported cases of ssRMS, the imaging characteristics of ssRMS are not established. Herein, we present the case of an elderly Japanese woman with ssRMS of the masticator space with intracranial invasion without destruction of the adjacent bone. Attention should be paid to the presence of intracranial infiltration that may indicate a worse prognosis. Tumor growth without bone destruction could be a key finding to differentiate ssRMSs from conventional subtypes of rhabdomyosarcoma.

MYOD1 (L122R) mutations are associated with spindle cell and sclerosing rhabdomyosarcomas with aggressive clinical outcomes

Recurrent mutations in the myogenic transcription factor MYOD1 and PIK3CA were initially described in a subset of embryonal rhabdomyosarcomas. Recently, two independent studies demonstrated presence of MYODI (L122R) mutations as the basis to re-classify a spindle cell rhabdomyosarcoma, along with a sclerosing rhabdomyosarcoma, distinct from an embryonal rhabdomyosarcoma. We analyzed a much larger cohort of 49 primary rhabdomyosarcoma tumor samples of various subtypes, collected over a period of 9 years, for the presence of MYOD1 (L122R), PIK3CA (H1047), and PIK3CA (E542/E545) mutations, along with immunohistochemical analysis of desmin, myogenin, and MYOD1. Although activating PIK3CA mutations were absent across the sample set analyzed, we report 20% MYOD1 (L122R) mutation in rhabdomyosarcomas, found exclusively in 10 of 21 spindle cell and sclerosing rhabdomyosarcomas, occurring mostly in the head and neck region along with extremity sites (64%), than the paratesticular and intra-abdominal sites. Furthermore, while all 10 MYOD1 mutant spindle cell and sclerosing rhabdomyosarcoma samples showed diffuse and strong MYOD1 immunoexpression, 7 of 31 samples of rhabdomyosarcoma with wild-type MYOD1 were negative for MYOD1 expression. Clinically, a striking correlation was found between MYOD1 mutation and the clinical outcomes available for 15 of 21 cases: 5 of 7 patients with spindle cell and sclerosing rhabdomyosarcomas, harboring MYOD1 mutation, were alive-with-disease and 2 of 8 patients with spindle cell and sclerosing rhabdomyosarcomas, with mutant MYOD1, were free-of-disease. Taken together, we present the first report of MYOD1 (L122R) mutation in the largest cohort of 49 rhabdomyosarcomas reported so far, that are associated with a relatively aggressive clinical course. Moreover, consistent with the earlier two studies, this study further reinforces a relationship between spindle cell and the sclerosing rhabdomyosarcoma-now recognized as a single subtype, distinct from an embryonal rhabdomyosarcoma.