Assessment of The Utility of The Sarcoma DNA Methylation Classifier In Surgical Pathology

Diagnostic classification of soft tissue tumors is based on histology, immunohistochemistry, genetic findings, and radiologic and clinical correlations. Recently, a sarcoma DNA methylation classifier was developed, covering 62 soft tissue and bone tumor entities. The classifier is based on large-scale analysis of methylation sites across the genome. It includes DNA copy number analysis and determines O6 methylguanine DNA methyl-transferase methylation status. In this study, we evaluated 619 well-studied soft tissue and bone tumors with the sarcoma classifier. Problem cases and typical examples of different entities were included. The classifier had high sensitivity and specificity for fusion sarcomas: Ewing, synovial, CIC-rearranged, and BCOR-rearranged. It also performed well for leiomyosarcoma, malignant peripheral nerve sheath tumors (MPNST), and malignant vascular tumors. There was low sensitivity for diagnoses of desmoid fibromatosis, neurofibroma, and schwannoma. Low specificity of matches was observed for angiomatoid fibrous histiocytoma, inflammatory myofibroblastic tumor, Langerhans histiocytosis, schwannoma, undifferentiated sarcoma, and well-differentiated/dedifferentiated liposarcoma. Diagnosis of lipomatous tumors was greatly assisted by the detection of MDM2 amplification and RB1 loss in the copy plot. The classifier helped to establish diagnoses for KIT-negative gastrointestinal stromal tumors, MPNSTs with unusual immunophenotypes, and undifferentiated melanomas. O6 methylguanine DNA methyl-transferase methylation was infrequent and most common in melanomas (35%), MPNSTs (11%), and undifferentiated sarcomas (11%). The Sarcoma Methylation Classifier will likely evolve with the addition of new entities and refinement of the present methylation classes. The classifier may also help to define new entities and give new insight into the interrelationships of sarcomas.

Purpose: This study sought to identify β-catenin targets that regulate desmoid oncogenesis and determine whether external signaling pathways, particularly those inhibited by sorafenib (e.g., PDGFRβ), affect these targets to alter natural history or treatment response in patients.

Experimental design: In vitro experiments utilized primary desmoid cell lines to examine regulation of β-catenin targets. Relevance of results was assessed in vivo using Alliance trial A091105 correlative biopsies.

Results: CTNNB1 knockdown inhibited hypoxia-regulated gene expression in vitro and reduced levels of HIF1α protein. ChIP-seq identified ABL1 as a β-catenin transcriptional target that modulated HIF1α and desmoid cell proliferation. Abrogation of either CTNNB1 or HIF1 inhibited desmoid cell-induced VEGFR2 phosphorylation and tube formation in endothelial cell co-cultures. Sorafenib inhibited this activity directly but also reduced HIF1α protein expression and c-Abl activity while inhibiting PDGFRβ signaling in desmoid cells. Conversely, c-Abl activity and desmoid cell proliferation were positively regulated by PDGF-BB. Reduction in PDGFRβ and c-Abl phosphorylation was commonly observed in biopsy samples from patients after treatment with sorafenib; markers of PDGFRβ/c-Abl pathway activation in baseline samples were associated with tumor progression in patients on the placebo arm and response to sorafenib in patients receiving treatment.

Conclusions: The β-catenin transcriptional target ABL1 is necessary for proliferation and maintenance of HIF1α in desmoid cells. Regulation of c-Abl activity by PDGF signaling and targeted therapies modulates desmoid cell proliferation, thereby suggesting a reason for variable biologic behavior between tumors, a mechanism for sorafenib activity in desmoids, and markers predictive of outcome in patients.

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Background: Head and neck fibromatoses (HNFs) are a rare, diverse group of soft tissue tumors characterized by an abnormal proliferation of fibroblasts. Available literature on these tumors is limited to case reports and small single-institutional studies.

Objective: We aim to provide demographic, socioeconomic, tumor-related, and treatment characteristics of HNFs.

Design: Retrospective cohort analysis using the National Cancer Database (NCDB).

Methods: The NCDB was queried for fibromatosis-related histologic codes located within the head and neck region. Various factors were analyzed. Univariate and multivariate survival analyses were performed.

Results: Between 2004 and 2016, 130 patients were included in the analyses. Average age was 57.4 years old with a predominance of White (83.6%) males (61.5%). Non-desmoid HNFs accounted for 60%-70% of the tumors. The salivary gland was the most common location (38.5%) and more than half of the tumors were high grade. The majority were treated surgically (90.8%) and 25% had positive margins. Mean and median overall survival (OS) were 98.9 and 135.4 months, respectively. Surgery is associated with better OS than nonsurgical alternatives. Addition of adjuvant treatments was not associated with differences in survival.

Conclusion: In the largest study to date, we describe demographic, socioeconomic, tumor-related, and treatment patterns of patients with this rare disease. These tumors are most frequently present in middle-aged males with high-grade histology. Most are treated surgically and positive surgical margins are common. Surgery has better OS than nonsurgical alternatives. While adjuvant radiation has become more common, we found no difference in survival compared to surgery alone.

Fibromatosis or desmoid tumors are rare benign fibroblastic lesions that are rarely present in the head and neck regions. When they do occur in these regions, however, they tend to be aggressive toward the surrounding tissue and be associated with heavy morbidity and mortality. We report the case of a 26-year-old Tunisian female who presented with acute obstructive dyspnea and a 3-week history of cervical swelling. The swelling was initially only located in the left submandibular area, it then gradually extended to all the anterior cervical supra- and infrahyoid regions causing a clinical presentation resembling that of obstructive dyspnea, the patient was admitted, and an emergency tracheotomy was performed. Tissue samples were taken, pathological analysis revealed an aggressive case of fibromatosis. The patient was treated with corticosteroids and antihormonal therapy, the fibrous mass shrunk considerably allowing the removal of the tracheotomy cannula, no tumor recurrence was noted during the observation period. Due to the rarity of this disease, especially in the cervical region, there are no therapeutic guidelines available.

Fibromatosis, or desmoid tumour, is characterized by excessive and infiltrative proliferation of connective tissue originating from aponeurotic muscle structures. Mammary fibromatosis is rare in humans and animals and its precise aetiology is unknown. A 10-year-old mixed-breed female dog developed a mass in the right cranial thoracic mammary gland (M1) and underwent lumpectomy. The mass was firm, with an irregular surface and distinct limits. Microscopically, it was a neoplastic proliferation of fusiform cells with low atypia, interspersed with abundant dense collagenous tissue, confirmed by histochemical staining with Gomori’s trichrome and Masson’s trichrome and immunopositivity for vimentin and smooth muscle actin, confirming mammary fibromatosis. Mammary fibromatosis in dogs needs further studies to elucidate its clinical, epidemiological and aetiopathogenic aspects.