Pediatric-type Myoid Neoplasms of Somatic Soft Tissue: A Clinicopathological and Molecular Genetic Study of 78 Tumors, Highlighting Indolent Clinical Behavior and Frequent SRF Gene Rearrangements.

Soft tissue tumors with smooth muscle differentiation are rare in pediatric patients. Despite often showing morphologic features sufficient for classification as "leiomyosarcoma" in adults (e.g.

YAP1::KMT2A-rearranged sarcomas harbor a unique methylation profile and are distinct from sclerosing epithelioid fibrosarcoma and low-grade fibromyxoid sarcoma.

Sclerosing epithelioid fibrosarcoma (SEF) was originally described as a peculiar variant of fibrosarcoma in 1995. Subsequent studies showed that conventional SEF was associated with both immunohistochemical expression of MUC4 and EWSR1/FUS gene rearrangements with CREB3L1 as the predominant fusion partner. Since then, a distinct group of fibrous tumors characterized by YAP1::KMT2A and KMT2A::YAP1 gene rearrangements and SEF-like morphology has been described.

SARCP, a Clinical Next-Generation Sequencing Assay for the Detection of Gene Fusions in Sarcomas: A Description of the First 652 Cases.

An amplicon-based targeted next-generation sequencing (NGS) assay for the detection of gene fusions in sarcomas was developed, validated, and implemented. This assay can detect fusions in targeted regions of 138 genes and BCOR internal tandem duplications. This study reviews our experience with testing on the first 652 patients analyzed.

Utilization of an artificial intelligence-enhanced, web-based application to review bile duct brushing cytologic specimens: A pilot study.

Background: The authors previously developed an artificial intelligence (AI) to assist cytologists in the evaluation of digital whole-slide images (WSIs) generated from bile duct brushing specimens. The aim of this trial was to assess the efficiency and accuracy of cytologists using a novel application with this AI tool.

Methods: Consecutive bile duct brushing WSIs from indeterminate strictures were obtained.

Myoepithelial Tumors of Bone With EWSR1::PBX3 Fusion: A Spectrum From Benign to Malignant.

The EWSR1::PBX3 fusion gene, commonly associated with cutaneous syncytial myoepitheliomas, is also found in myoepithelial tumors (METs) of bone and soft tissue. These tumors typically demonstrate benign histology and favorable outcomes. This study examines 6 previously unreported intraosseous METs harboring the EWSR1::PBX3 fusion, focusing on their histopathologic characteristics, immunophenotype, clinical and radiographic profiles, and patient outcomes.

Disseminated infection in a patient with diffuse large B-cell lymphoma treated with immunotherapy.

Immunotherapies can lead to an immune compromised state that can allow for opportunistic pathogens such as to flourish. The vast majority of infections occur in immunocompromised hosts. Here we describe disseminated infection in a patient with diffuse large B-cell lymphoma treated with immunotherapy.

Myxofibrosarcoma: Outcomes, Prognostic Factors, and Role of Neoadjuvant Radiation Therapy.

Purpose: Myxofibrosarcoma (MFS) is a subtype of soft tissue sarcoma with a highly infiltrative growth pattern that leads to a higher risk of inadvertent positive surgical margins and local relapse. Poorly defined tumor margins also pose a challenge for radiation therapy (RT) planning, in terms of treatment volumes and administration of pre- versus postoperative RT. This study aims to evaluate local control and patterns of recurrence in patients with MFS treated with neoadjuvant RT followed by definitive surgical excision.

DNA Methylation Profiling Distinguishes Adamantinoma-Like Ewing Sarcoma From Conventional Ewing Sarcoma.

Adamantinoma-like Ewing sarcoma (ALES) has traditionally been considered a variant of Ewing sarcoma because it generally harbors EWSR1::FLI1 fusions despite showing diffuse positivity for keratins and p40. However, it has become increasingly recognized that different tumors can have identical translocations, including shared fusions between carcinomas and sarcomas, raising questions as to whether ALES might represent a separate entity. Using methylation profiling, we further explored the relationship between Ewing sarcoma and ALES.

Lipoblastoma-Like Tumor and Fibrosarcoma-Like Lipomatous Neoplasm Represent the Same Entity: A Clinicopathologic and Molecular Genetic Study of 23 Cases Occurring in Both Men and Women at Diverse Locations.

Lipoblastoma-like tumor (LLT) is a benign soft tissue tumor demonstrating mixed morphologic features of lipoblastoma, myxoid liposarcoma, and spindle cell lipoma but lacking genetic alterations associated with those tumors. LLT was originally thought to be specific to the vulva but has since been reported in the paratesticular region. The morphologic features of LLT overlap with those of "fibrosarcoma-like lipomatous neoplasm" (FLLN), a rare, indolent adipocytic neoplasm considered by some to form part of the spectrum of atypical spindle cell and pleomorphic lipomatous tumor.

Revisiting the cytologic features of autoimmune pancreatitis: An institutional experience.

Background: Autoimmune pancreatitis (AIP) is a known mimicker of pancreatic ductal adenocarcinoma both clinically and radiologically. In this study, the authors present their institutional experience in diagnosing AIP on cytology and correlate results with the histologic findings.

Methods: A 14-year computerized search for patients who had histologically confirmed AIP with concurrent or prior cytology was performed.

Metastatic melanoma involving a genetically confirmed angiofibroma of soft tissue: A previously unreported type of tumor-to-tumor metastasis.

Tumor-to-tumor metastases are an uncommon phenomenon and are very rare in the context of malignant melanoma. This case report describes a 73-year-old male who underwent an excision of a melanoma from his forehead. Six months later, he developed metastatic disease, including metastasis to a genetically confirmed angiofibroma of soft tissue of the abdominal wall.

Plexiform fibrohistiocytic tumor: a clinicopathological and immunohistochemical study of 39 tumors, with evidence for a CSF1-producing "null cell" population.

Plexiform fibrohistiocytic tumor (PFHT) is a mesenchymal tumor of intermediate malignancy, typically occurring in the superficial soft tissues of young patients and displaying a biphasic pattern, with nodules of histiocytoid cells surrounded by fascicles of myofibroblastic spindled cells. The pathogenesis of PHFT is unknown. We comprehensively studied 39 PFHT, occurring in 25 females (66%) and 13 males (34%), ranging from 2 to 55 years of age (median 21 years).

Pleomorphic Liposarcoma: A Series of 120 Cases With Emphasis on Morphologic Variants.

Pleomorphic liposarcoma (PLPS) is a highly aggressive sarcoma comprising variable numbers of pleomorphic lipoblasts mixed with undifferentiated pleomorphic sarcoma (UPS)-like areas. Morphologic variants, such as myxofibrosarcoma-like or epithelioid, may cause diagnostic confusion, especially on a core biopsy, but there are few data on the prognostic significance of these features. A total of 120 PLPS biopsies and resection specimens were reviewed and catalogued based on the presence of myxofibrosarcoma-like, UPS-like, and epithelioid foci, in 10% increments.

Desmoid fibromatosis involving the pancreas: A retrospective case series with clinical, cytopathologic and radiologic correlation.

Desmoid-type fibromatosis (desmoid tumors) which involve the pancreas is an infrequent diagnosis which clinically can mimic both neoplastic and non-neoplastic lesions of the pancreas. The cytologic features of loosely cohesive cytologically bland (myo)fibroblastic cells are non-specific, however the long fascicular growth pattern and the presence of β-catenin mutation with positive nuclear immunohistochemical staining or molecular testing allows for definitive diagnosis. While many previously reported desmoid tumors of the pancreas have been surgically resected, conservative management with a "watch and wait" approach is also an effective mode of management for these tumors.

Loss of dimethylated H3K27 (H3K27me2) expression is not a specific marker of malignant peripheral nerve sheath tumor (MPNST): An immunohistochemical study of 137 cases, with emphasis on MPNST and melanocytic tumors.

Introduction: Loss-of-function mutations in EED and SUZ12, core components of the polycomb repressive complex 2 (PRC2), occur in >90% of sporadic and radiation-associated malignant peripheral nerve sheath tumors (MPNST) and in roughly 70% of NF1-related tumors. PRC2 inactivation results in loss of H3K27me3 expression and aberrant downstream transcription. H3K27me3 expression is lost in 40-90% of spindle cell MPNST but is not specific.

Biphasic squamoid alveolar renal cell carcinoma: Cytologic features of a rare entity.

Biphasic squamoid alveolar renal cell carcinoma is a newly described rare morphologic variant of papillary renal cell carcinoma. Its characteristic histomorphology and immunophenotype have been well described in the literature. Namely, BSARCC is composed of a dual-cell population with nests of larger squamoid cells surrounded by a single layer of cuboidal cells in alveolar arrangements.

Mammary analogue secretory carcinoma: A challenging case arising in a young man with radiation exposure.

Mammary Analogue Secretory Carcinoma (MASC) is a recently described salivary gland tumor frequently sampled via fine-needle aspiration. The cytologic features of MASC are not entirely distinctive and can simulate acinic cell carcinoma, but the tumor harbors an ETV6 gene rearrangement resulting in an ETV6-NTRK3 fusion gene. We present a case of MASC arising in a 31 year old man with a history of multiple radio-embolization procedures.

Head and Neck Low-Grade Fibromyxoid Sarcoma: A Clinicopathologic Study of 15 Cases.

Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon mesenchymal tumor usually arising in the lower extremities and trunk. Only rare examples in the head and neck region have been reported. Fifteen cases of head and neck LGFMS were retrieved.

Malignant gastrointestinal neuroectodermal tumor: Cytologic, histologic, immunohistochemical, and molecular pitfalls.

Malignant gastrointestinal neuroectodermal tumor (GNET) is a rare malignant primary gastrointestinal mesenchymal tumor which can be diagnosed via fine-needle aspiration (FNA) cytology. In the context of FNA, the diagnosis requires a cell block and the use of significant resources including immunohistochemical stains and molecular testing. The differential diagnosis of GNET includes clear cell sarcoma (CCS), gastrointestinal stromal tumor (GIST), gastric schwannoma, metastatic melanoma, malignant perivascular epithelioid cell tumor (PEComa) and granular cell tumor, among others.

Bone and soft tissue sarcomas in cerebrospinal fluid and effusion: A 20-year review at our institution.

Background: The literature on bone and soft tissue sarcomas (BSTSs) involving effusions and cerebrospinal fluid (CSF) is very limited.

Methods: A computerized search for fluid cytology with a sarcoma diagnosis from 2000 to 2020 was performed. All available cases, including the clinical follow-up, were reviewed.