Klotho Overexpression Is Frequently Associated With Upstream Rearrangements in Fusion-Negative Phosphaturic Mesenchymal Tumors of Bone and Sinonasal Tract.

Phosphaturic mesenchymal tumors (PMT) are uncommon neoplasms that cause hypophosphatemia/osteomalacia mainly by secreting fibroblast growth factor 23. We previously identified FN1::FGFR1/FGF1 fusions in nearly half of the PMTs and frequent KL (Klotho or α-Klotho) overexpression in only those with no known fusion. Here, we studied a larger cohort of PMTs for KL expression and alterations. By FN1 break-apart fluorescence in situ hybridization (FISH) and reappraisal of previous RNA sequencing data, 6 tumors previously considered "fusion-negative" (defined by negative results of FISH for FN1::FGFR1 fusion and FGF1 break-apart and/or of RNA sequencing) were reclassified as fusion-positive PMTs, including 1 containing a novel FN1::ZACN fusion. The final cohort of fusion-negative PMTs included 33 tumors from 32 patients, which occurred in the bone (n = 18), soft tissue (n = 10), sinonasal tract (n = 4), and brain (n = 1). In combination with previous work, RNA sequencing, RNA in situ hybridization, and immunohistochemistry showed largely concordant results and demonstrated KL/α-Klotho overexpression in 17 of the 28 fusion-negative and none of the 10 fusion-positive PMTs studied. Prompted by a patient in this cohort harboring germline KL upstream translocation with systemic α-Klotho overexpression and multifocal PMTs, FISH was performed and revealed KL rearrangement in 16 of the 33 fusion-negative PMTs (one also with amplification), including 14 of the 17 cases with KL/α-Klotho overexpression and none of the 11 KL/α-Klotho-low fusion-negative and 11 fusion-positive cases studied. Whole genomic sequencing confirmed translocation and inversion in 2 FISH-positive cases involving the KL upstream region, warranting further investigation into the mechanism whereby these rearrangements may lead to KL upregulation. Methylated DNA immunoprecipitation and sequencing suggested no major role of promoter methylation in KL regulation in PMT. Interestingly, KL-high/-rearranged cases seemed to form a clinicopathologically homogeneous group, showing a predilection for skeletal/sinonasal locations and typically matrix-poor, cellular solitary fibrous tumor-like morphology. Importantly, FGFR1 signaling pathways were upregulated in fusion-negative PMTs regardless of the KL status compared with non-PMT mesenchymal tumors by gene set enrichment analysis, perhaps justifying FGFR1 inhibition in treating this subset of PMTs.

Clinicopathological and treatment response characteristics of updated rhabdomyosarcoma histomolecular subtypes: An Asian population-based study.

AIM: New histomolecular subtypes of rhabdomyosarcoma have recently been defined but their corresponding clinical characteristics are not well described. Also, these clinical phenotypes vary greatly by age and ethnicity but have not been profiled in Asian populations. Thus, we sought to determine the landscape of rhabdomyosarcoma subtypes in a national Asian cohort and compare clinical characteristics among age groups and molecular subtypes. METHODS: We performed a retrospective population-based study of all rhabdomyosarcoma patients in Singapore public hospitals from 2004 to 2014 (n = 67), and assigned histomolecular subtypes according to the updated 2020 WHO classification of soft tissue tumors following central pathology review and molecular profiling. RESULTS: Age-specific prevalence followed a tri-modal peak. There were significantly more embryonal and alveolar (p = 0.032) and genitourinary (non-bladder/prostate) tumors (p = 0.033) among children. Older age was associated with complete resection among spindle cell/sclerosing tumors (p = 0.027), with the omission of chemotherapy among embryonal tumors (p = 0.001), and with poorer survival among embryonal and alveolar tumors (p = 0.026, p = 0.022, respectively). Overall survival differed with stage, group, and surgical resection, adjusted for age group (p = 0.004, p = 0.001, p = 0.004, respectively). Spindle-cell/sclerosing tumors showed an indolent phenotype with a significantly lower incidence of nodal metastasis (p = 0.002), but two of 15 patients with MYOD1 mutations had a contrastingly aggressive disease. CONCLUSION: Disease and treatment response profiles of rhabdomyosarcoma subtypes vary significantly between adults and children, especially surgical resectability. In our Asian population, poorer outcomes were observed in adults with embryonal and alveolar tumors, while activating mutations influence the behavior of otherwise favorable spindle cell/sclerosing tumors.

Expanding the spectrum of GLI1-altered mesenchymal tumors-A high-grade uterine sarcoma harboring a novel PAMR1::GLI1 fusion and literature review of GLI1-altered mesenchymal neoplasms of the gynecologic tract.

GLI1-altered mesenchymal tumors comprise a group of seemingly unrelated entities, including pericytoma with t(7;12) translocation, plexiform fibromyxoma, gastroblastoma, malignant epithelioid neoplasm with GLI1 rearrangements, and GLI1-amplified mesenchymal neoplasms. Herein, we report a high-grade uterine sarcoma harboring a novel PAMR1::GLI1 fusion and present a literature review of GLI1-altered mesenchymal neoplasms of the gynecologic tract. A 57-year-old female presented with an abdomino-pelvic mass, felt since a decade prior. Magnetic resonance imaging showed a heterogenous myometrial mass extending beyond the serosa. The patient underwent oncologic surgical resection. Gross examination revealed a perforated multi-nodular uterine tumor (21 cm) with a firm white and soft fleshy cut surface, featuring hemorrhage and necrosis. The tumor was morphologically heterogenous, disclosing frankly sarcomatous areas composed of pleomorphic spindle and focally epithelioid cells, intermingled with a component of low-grade spindle cells arranged in fascicles. There was a rich vascular network and zones of necrosis with peripheral amianthoid-like collagen plaques. Lymphovascular invasion and metastasis to lymph nodes and omentum were present. The tumor was immunopositive for CD10 and cyclinD1, and negative for cytokeratins, myogenic, melanotic, and hormonal markers. ArcherTM Fusion Sarcoma Assay detected PAMR1(exon1)::GLI1(exon4) fusion, confirmed on RT-PCR and Sanger sequencing. The patient received chemo-radiotherapy, however, developed metastatic recurrence and demised 18 months post-surgery. Altogether, this is a rare and diagnostically challenging case of a uterine sarcoma harboring a novel GLI1 fusion. Emerging GLI/Hedgehog inhibitors provide clinical relevance to recognizing these tumors in modern pathology.

Inflammatory myofibroblastic tumour of the rectum with a novel anaplastic lymphoma kinase fusion diagnosed on cytology: Not just another submucosal gastrointestinal stromal tumour!

Inflammatory myofibroblastic tumours (IMT) are spindle cell neoplasms most commonly seen in the lungs, with a wide variety of less common extrapulmonary sites including the mesentery, omentum, and intrabdominal sites. On cytological evaluation, these tumours can be difficult to diagnose, given the morphological mimics of other submucosal spindle cell neoplasms, which may be compounded by the relatively small amount of tissue and the uncommon nature of the diagnosis. Immunohistochemical staining and molecular studies for the ALK gene can prove useful for diagnosing this tumour. We present the cytological features of an IMT occurring in the rectum, the differential diagnoses, useful immunohistochemical staining patterns, and the additional finding of a novel ALK-fusion in this entity.

Expanding the Spectrum of Adult NTRK3-Rearranged Spindle Cell Neoplasms: A Recurrent NTRK3-SQSTM1 Fusion Spindle Cell Tumor With Deceptively Bland Morphology.

OBJECTIVES: NTRK-rearranged spindle cell neoplasms (other than infantile fibrosarcoma) are an emerging entity of tumors that demonstrate wide variation in clinical and histopathologic features. We report a case of an NTRK-rearranged spindle cell neoplasm bearing a deceptively bland morphology. METHODS: We performed histopathologic, immunohistochemical, and molecular evaluation on resection tissue. We also conducted a literature review on adult NTRK3-rearranged spindle cell neoplasms. RESULTS: The tumor presented as a recurrent ankle mass in an elderly patient. Histologically, it was composed of bland spindle cells set in a fibrous to edematous stroma. Blood vessels were interspersed with subtle perivascular hyalinization and scattered lymphoid aggregates. Immunohistochemically, the spindle cells expressed CD34 and S100 while being negative for SOX10. The tumor also showed cytoplasmic reactivity for pan-tyrosine receptor kinase immunohistochemistry. Next-generation sequencing identified an NTRK3-SQSTM1 fusion. To the best of our knowledge, this fusion pair has not been previously reported in adult NTRK-rearranged mesenchymal tumors. CONCLUSIONS: Altogether, this rare and diagnostically challenging case of an NTRK3-rearranged spindle cell tumor with low-grade morphology is in contrast to many of the reported adult NTRK3-rearranged mesenchymal tumors. Recognition of low-grade NTRK-rearranged tumors demands close attention to clues in morphology and immunoprofiles.

Breast metastasis from endometrial clear cell carcinoma: A case report and review of the literature.

Metastasis to the breast from extra-mammary malignancies are rare, accounting for less than 1% of all breast cancers. Endometrial cancer, a common gynecological malignancy, often spreads to the pelvis, abdominal lymph nodes, peritoneum or the lungs. Endometrial metastasis to the breast is extremely rare, and while there have been isolated case reports of endometrial serous carcinoma with breast metastasis, it has not been reported in the case of clear cell carcinoma. We present a rare case of a 70 year old Chinese lady who had a metastatic endometrial clear cell carcinoma with metastasis to the breast, mimicking an inflammatory breast cancer clinically. We reviewed the current literature and describe the challenges in differentiating primary from metastatic breast lesions, as well as clinical, radiological and histopathological features that may help to differentiate the two. Tumour metastasis to the breast via lymphatic or hematogenous route can affect their radiological features: the former mimicking inflammatory breast cancer and the latter with features similar to benign breast lesions. Regardless, histological features with immunohistochemical staining is still the gold standard in diagnosing metastatic breast lesions and determining their tissue of origin. Breast metastases from extra-mammary malignancies are uncommon and it is even rarer for endometrial clear cell carcinoma to spread to the breast. Nonetheless, this case highlights the importance of keeping an open mind and engaging a multidisciplinary team for the care of complex patients.

Giant Cell Tumor of Bone With Cartilage Matrix: A Clinicopathologic Study of 17 Cases.

Giant cell tumor of bone (GCT) is a benign locally aggressive neoplasm composed of mononuclear cells admixed with innumerable osteoclast-type giant cells. H3F3A gene mutations producing mutant histone protein product H3.3 have been identified in 96% of GCT; mutant H3.3 is reliably demonstrated by immunohistochemistry. GCT may contain woven bone and rarely, neoplastic cartilage nodules which causes diagnostic challenges with aggressive neoplasms such as osteosarcoma. We describe the features of GCT with cartilage matrix and report the next-generation sequencing findings in a subset of tumors. Seventeen cases of GCT with cartilage matrix form the cohort: 7 males and 10 females, 13 to 55 (mean: 25) years old. Tumors involved the fibula (6), femur (6), and patella, tibia, humerus, S1, and scapula (1 case each). Tumors were radiolucent, circumscribed, lytic, and expansile. All contained classic GCT, foci of cartilage matrix, and trabeculae of woven bone. Immunohistochemistry showed diffuse staining for H3.3 in 9/9 cases and 1 case was positive for S100 and SOX9 in the cartilage areas. Next-generation sequencing showed a mutation in the H3F3A gene in 6/6 cases. On follow-up, 2 patients who underwent resection showed no disease after 12, and 7 months, respectively. Three patients had recurrences 10, 12, and 27 months after curettage; there were no metastases. GCT with cartilage matrix is uncommon. The cartilage matrix is associated with woven bone suggesting the neoplastic cells may differentiate into chondrocyte-like and osteoblast-like cells. Recognition of this neoplasm is important to prevent misdiagnosis and overtreatment of affected patients.

Malignant transformation in a sciatic plexiform neurofibroma in Neurofibromatosis Type 1 - imaging features that aid diagnosis.

A 41-year-old Asian male with NF1 and bilateral sciatic plexiform neurofibromas, presented with unintentional weight loss, increasing size of a left thigh mass associated with increasing pain and radiculopathy. MRI of the left thigh demonstrated imaging features suspicious of malignant transformation. The patient had a new left lung mass, demonstrating avid FDG uptake, raising suspicion for metastasis. Surgical resection of the left thigh mass confirms malignant transformation in a preexisting sciatic plexiform neurofibroma. Diagnosis of malignant transformation in a nerve sheath tumour can be challenging. MRI remains the main preferred imaging modality in the evaluation of these tumours. Imaging features that raise suspicion for malignant transformation are discussed. Although none of these are specific for malignant transformation, studies suggest that the presence of two to four of these features should prompt further investigations.

Frequent overexpression of klotho in fusion-negative phosphaturic mesenchymal tumors with tumorigenic implications.

Phosphaturic mesenchymal tumors (PMT) are tumors that cause hypophosphatemia/osteomalacia chiefly by secreting FGF23. We have identified FN1-FGFR1/FGF1 fusion genes in nearly half of PMT, suggesting a central role of FGFR1 pathways in the pathogenesis of PMT. Tumorigenic drivers are unknown for tumors where previous study detected neither fusion, including many in bone, where FISH failed because of tissue decalcification. To identify alternative fusions in PMT without known fusions, as well as to validate the positive FISH results and characterize the fusion junctions, 34 PMT were studied, including 12 with known FN1-FGFR1 fusion by FISH (Group A), 2 with FN1-FGF1 (B), 12 with neither fusion (C), and 8 with previous acid-based decalcification and hence unknown fusion status (D). In total, 23 archival samples were subjected to anchored multiplex PCR-based RNA-sequencing (AMP-seq) with primers targeting FN1, genes encoding the FGF/FGFR families, and KL (α-Klotho); five Group C cases were also studied with whole-transcriptomic and exome-captured RNA sequencing, respectively. The AMP-seq results were consistent with previous FISH and/or transcriptomic sequencing data, except in one old Group A sample. One case had a novel FGFR1 exon 9 breakpoint, confirmed by genomic DNA sequencing. One Group D bone tumor was found to harbor FN1-FGF1. All 3 RNA-sequencing platforms failed to identify convincing fusion genes in Group C (N = 10), which instead expressed significantly higher levels of either KL or KLB. This result was further confirmed with KL and KLB RNA CISH semi-quantification (RNAscope). Our results demonstrated the utility of AMP-seq, which was compromised by decalcification and prolonged archiving. Of potential importance, fusion-negative PMT frequently overexpressed α-Klotho (or instead ß-Klotho less commonly), whose role as an obligatory co-receptor for FGF23-FGFR1 binding suggests its aberrant expression in osteocytes/osteoblasts might result in an FGF23-FGFR1 autocrine loop that in turn drives the overexpression of FGF23 and tumorigenesis through activated FGFR pathways.

Biological significance and prognostic relevance of peripheral blood neutrophil-to-lymphocyte ratio in soft tissue sarcoma.

Peripheral blood indices of systemic inflammation such as the neutrophil-lymphocyte ratio (NLR) have been shown to be prognostic in various cancers. We aim to investigate the clinical significance of these indices in patients with soft tissue sarcoma (STS). Seven hundred and twelve patients with available blood counts at diagnosis and/or metastatic relapse were retrospectively examined. An optimal cutoff for NLR-high (>2.5) in predicting overall survival (OS) was determined using receiver operating curve analyses. Survival analyses were performed using the Kaplan-Meier method and multivariate Cox proportional models. Our results show that NLR was significantly higher in patients with distant metastasis at diagnosis (n = 183) compared to those without (n = 529) (median: 4.36 vs 2.85, p < 0.0001). Progression of localized disease at diagnosis to metastatic relapse within the same patients was associated with an interval increase in NLR (median: 3.21 vs 3.74, p = 0.0003). In multivariate analysis, NLR-high was the only consistent factor independently associated with both worse OS (HR 1.53, 95% CI 1.10-2.13, p = 0.0112) and relapse-free survival (HR 1.41, 95% CI 1.08-1.85, p = 0.0125) in localized disease, as well as OS (HR 1.82, 95% CI 1.16-2.85, p = 0.0087) in metastatic/unresectable disease. In conclusion, high NLR is an independent marker of poor prognosis among patients with STS.

Proximal Ulna: A Rare Location for Solitary Intraosseous Hemangioma.

Intraosseous hemangiomas are rare, benign bone tumors usually affecting the bones of the axial skeleton. Its incidence in the long bones is extremely rare. We report a 19-year-old boy with solitary intraosseous hemangioma of the proximal ulna. Radiographs and computed tomography images showed a well-defined osteolytic lesion involving the right proximal ulna. Magnetic resonance imaging showed intermediate signal intensity on T1-weighted images and increased signal intensity on T2-weighted images with internal trabeculae and peripheral post-contrast enhancement. Postcurettage histologic diagnosis of intraosseous hemangioma was made.

Primary Bone Anaplastic Large Cell Lymphoma Masquerading as Ewing Sarcoma: Diagnosis by Anchored Multiplex PCR.

A 3-year-old boy presented with pathologic fracture of the left proximal femur. Magnetic resonance imaging revealed an aggressive expansile bony mass associated with cortical destruction and surrounding myositis. Computed tomography-guided biopsy revealed a monomorphic small round blue cell tumor by histology. CD99 immunoreactivity and low-level EWSR1 gene translocation by break-apart fluorescent in situ hybridization initially favored a diagnosis of Ewing sarcoma and chemotherapy commenced. Subsequent molecular evaluation by an anchored multiplex polymerase chain reaction-based assay (Archer FusionPlex Sarcoma Panel) revealed a nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) gene fusion. The diagnosis was then amended to primary bone ALK-positive anaplastic large cell lymphoma and the chemotherapy regimen was modified accordingly. This report illustrates the value of this molecular assay in establishing the correct diagnosis of a very rare malignancy masquerading as another tumor type.

Treatment and outcomes of melanoma in Asia: Results from the National Cancer Centre Singapore.

BACKGROUND: Acral melanoma (AM) and mucosal melanoma (MM) make up more than half of melanomas in Asia but comprise only 5% of cases in Caucasians, where cutaneous melanoma (CM) predominates. AM and MM are thought to be genetically and biologically distinct from CM. We report the characteristics and outcomes of melanoma patients from the National Cancer Centre Singapore. METHODS: Case records of 210 patients treated between 2002 and 2014 were reviewed. RESULTS: Median follow-up was 2.5 years. CM, AM and MM made up of 37.6%, 33.8% and 16.2% of cases, respectively, with 6.2% each having ocular melanoma and unknown primary. Caucasians made up 16.2% of patients, accounting for 36.7% of CM but only 2.8 of AM and 2.9% of MM. Patients with MM (2.9% stage I, 14.7% stage IV) presented with higher American Joint Committee on Cancer (AJCC) stage than those with AM (16.9% stage I, 5.6% stage IV) or CM (24.1% stage I, 8.9% stage IV) (P = 0.01). Median overall survival (OS) was 5.7 years for all patients, and 1.0 year for metastatic disease. Considering stage I-III disease, multivariable Cox regression analysis demonstrated age ≥60 years and higher stage to be independent adverse prognostic factors for RFS and OS. Sentinel lymph node biopsy, undertaken for 56 stage I-III patients (25 AM, 31 CM) did not influence outcome. CONCLUSION: Our study reinforces the known unique clinicopathologic features of melanomas in Asians where AM and MM predominate. Age and stage remain the most critical prognostic factors across all subtypes.

Pulmonary sclerosing pneumocytoma with mediastinal lymph node metastasis.

Pulmonary sclerosing pneumocytoma is a rare tumour with 23 cases reported to have metastasis to lymph nodes, but to date, only 6 had involved mediastinal nodal stations. Our patient was a 40-year-old Asian female with a 2.5 cm nodule in her right lower lobe. Positron-emission tomography suggested no nodal disease; but after resection, the intra-lobular, hilar and subcarinal nodes were all found to be involved. As prognosis of this rare disease is uncertain, we aim to report our findings against available literature and similar cases.

Characterization of FN1-FGFR1 and novel FN1-FGF1 fusion genes in a large series of phosphaturic mesenchymal tumors.

Phosphaturic mesenchymal tumors typically cause paraneoplastic osteomalacia, chiefly as a result of FGF23 secretion. In a prior study, we identified FN1-FGFR1 fusion in 9 of 15 phosphaturic mesenchymal tumors. In this study, a total of 66 phosphaturic mesenchymal tumors and 7 tumors resembling phosphaturic mesenchymal tumor but without known phosphaturia were studied. A novel FN1-FGF1 fusion gene was identified in two cases without FN1-FGFR1 fusion by RNA sequencing and cross-validated with direct sequencing and western blot. Fluorescence in situ hybridization analyses revealed FN1-FGFR1 fusion in 16 of 39 (41%) phosphaturic mesenchymal tumors and identified an additional case with FN1-FGF1 fusion. The two fusion genes were mutually exclusive. Combined with previous data, the overall prevalence of FN1-FGFR1 and FN1-FGF1 fusions was 42% (21/50) and 6% (3/50), respectively. FGFR1 immunohistochemistry was positive in 82% (45/55) of phosphaturic mesenchymal tumors regardless of fusion status. By contrast, 121 cases of potential morphologic mimics (belonging to 13 tumor types) rarely expressed FGFR1, the main exceptions being solitary fibrous tumors (positive in 40%), chondroblastomas (40%), and giant cell tumors of bone (38%), suggesting a possible role for FGFR1 immunohistochemistry in the diagnosis of phosphaturic mesenchymal tumor. With the exception of one case reported in our prior study, none of the remaining tumors resembling phosphaturic mesenchymal tumor had either fusion type or expressed significant FGFR1. Our findings provide insight into possible mechanisms underlying the pathogenesis of phosphaturic mesenchymal tumor and imply a central role of the FGF1-FGFR1 signaling pathway. The novel FN1-FGF1 protein is expected to be secreted and serves as a ligand that binds and activates FGFR1 to achieve an autocrine loop. Further study is required to determine the functions of these fusion proteins.

Brain metastasis in sarcoma: Does metastasectomy or aggressive multi-disciplinary treatment improve survival outcomes.

AIM: Brain metastasis is rare in sarcoma. Prognostic factors, optimal management strategies and therapeutic outcomes of such patients are not well studied. We aimed to evaluate the incidence, clinical characteristics and treatment outcomes of parenchymal brain metastasis in sarcoma patients. METHODS: This is a single center retrospective analysis. Overall survival (OS) was calculated from the time of diagnosis of brain metastasis to time of death. RESULTS: Sixteen patients (2.1%) with complete electronic medical records treated at our institution from 2002 to 2010 were identified. Median age was 52 years; 88% had additional sites of metastases. Eight different subtypes of soft tissue and bone sarcoma were identified. Eighty-one percent of the patients developed metachronous brain metastasis at a median of 14 months after initial sarcoma diagnosis. Thirty-eight percent of patients had solitary brain metastasis and 44% underwent aggressive therapy for brain metastasis, defined as either surgical resection or multimodality treatment. The remaining 56% received conservative treatment (either whole brain radiation alone, chemotherapy alone or best supportive care). Median OS for the entire cohort was 3.5 months (95% CI 1.1-6.3 months). A trend toward improved OS was observed with an aggressive treatment approach, 3.7 months versus 1.2 months (P = 0.077) and the usage of chemotherapy (P = 0.071). CONCLUSION: Brain metastasis in sarcoma is rare, usually coexists with significant systemic disease and is associated with a grave prognosis. Use of chemotherapy and an aggressive treatment approach in well-selected patients may be associated with improved survival. Prospective studies are needed to confirm these findings.