Fascicular Growth Pattern Research Articles

Primary Malignant Peripheral Nerve Sheath Tumor in the Liver with Glandular Differentiation

Abstract Introduction/Objective Malignant peripheral nerve sheath tumors (MPNST) most commonly affect the proximal extremities and paraspinal region. Primary hepatic MPNST is extremely rare. Here we report a primary hepatic MPNST with heterologous glandular differentiation in a patient with Neurofibromatosis type 1 (NF1). Methods/Case Report Review of the clinical features and histopathological findings of the resected specimen. A review of all the published cases of primary liver MPNST. Results (if a Case Study enter NA) A 69-year-old male patient with a history of NF1, Gastrointestinal Stromal Tumor and treated hepatitis C without pre-existed neurofibroma presented with jaundice. Imaging revealed an ill-defied hypodense mass in the left hepatic lobe. A segmentectomy of the liver revealed an infiltrating 10 cm heterogenous yellow-white-pink slightly firm tumor with 5% necrosis. The tumor showed biphasic histology composed of predominantly spindle cells and clusters of glandular components. The spindle cells showed fascicular growth pattern with vaguely marbled appearance. Focal osteoclast-like multinucleated cells were seen. The glands were well defined, mostly appeared to be low grade, and lined by cuboidal to columnar cells, with a bile-duct and intestinal-like appearance. However, focal malignant glands with hepatic differentiation were also noted. Immunohistochemistry showed patchy loss of H3K27me3 in the spindle cells. The glandular cells were positive for AE1/AE3, CK7 and CK20. The tumor cells showed rare reactivity to TLE1 and were negative for S-100, SOX10, CD34, CD117 and DOG1. These findings supported the diagnosis of MPNST with glandular differentiation. 13 cases of primary MPNST of liver have been reported, and only one case described epithelioid differentiation. Conclusion The differential diagnoses of a primary hepatic biphasic tumor include sarcomatoid carcinoma, carcinosarcoma, biphasic synovial sarcoma and MPNST. Our case illustrates a rare biphasic hepatic MPNST. The morphology and loss of H3K27me3 expression by immunohistochemistry in a patient with NF1 support this challenging diagnosis.

Uterine Leiomyosarcoma Associated With Perivascular Epithelioid Cell Tumor: A Phenomenon of Differentiation/Dedifferentiation and Evidence Suggesting Cell-of-Origin.

Perivascular epithelioid cell tumor (PEComa) is a mesenchymal tumor thought to originate from perivascular epithelioid cells (PECs). The normal counterpart to PEC, however, has not been identified in any human organ, and the debate as to whether PEComa is related to smooth muscle tumors has persisted for many years. The current series characterizes 4 cases of uterine leiomyosarcoma (LMS) coexisting with PEComas. All cases exhibited an abrupt transition from the LMS to PEComa components. The LMS component displayed typical spindled morphology and fascicular growth pattern and was diffusely positive for desmin and smooth muscle myosin heavy chain, completely negative for HMB-45 and Melan A, and either negative or had focal/weak expression of cathepsin K and GPNMB. In contrast, the PEComa tumor cells in case 1 contained glycogen or lipid-distended cytoplasm with a foamy appearance (low grade), and in cases 2, 3, and 4, they displayed a similar morphology characterized by epithelioid cells with eosinophilic and granular cytoplasm and high-grade nuclear atypia. Different from the LMS component, the epithelioid PEComa cells in all cases were focally positive for HMB-45, and diffusely immunoreactive for cathepsin K and GPNMB. Melan A was focally positive in cases 1 and 3. Loss of fumarate hydratase expression (case 1) and RB1 expression (cases 2, 3, 4) was identified in both LMS and PEComa components, indicating that they are clonally related. In addition, both components showed an identical TP53 p.R196* somatic mutation and complete loss of p53 and ATRX expression in case 2 and complete loss of p53 expression in case 3. We hypothesize that LMSs containing smooth muscle progenitor cells may give rise to divergent, lineage-specific PEComatous lesions through differentiation or dedifferentiation. While we do not dispute the recognition of PEComas as a distinct entity, we advocate the hypothesis that modified smooth muscle cells represent the origin of a subset of PEComas, and our case series provides evidence to suggest this theory.

A148 OSTEOSARCOMA GASTROINTESTINAL METASTASIS: A RARE ENTITY IN ADULTS

Abstract Background Osteosarcoma is highly aggressive and is the most common primary bone malignancy for both children and adults with a bimodal age distribution. The first peak coincides with pubertal growth spurt and the second is in the seventh and eighth decade of life. They frequently metastasize to the lungs. Metastasis to the gastrointestinal tract is extremely rare and to our knowledge, there have only been 15 cases reported in the literature since 1987, of those only three in the second peak. Aims Describe a case of 61-year-old female with periampullary metastatic osteosarcoma. Describe the demographics of osteosarcoma patients who develop gastrointestinal metastasis. Methods Search Pubmed using the terms: ("Osteosarcoma"[MeSH Terms] OR "Osteosarcoma"[Title/Abstract]) AND ("Gastrointestinal Tract"[MeSH Terms] OR "Gastrointestinal Tract"[Title/Abstract] AND "Case Reports"[Publication Type]. 113 articles were identified and screened by title. 15 articles were further screened by abstract or full text. 7 articles were identified. the remainder 7 articles were located by screening the references of the previously identified articles. Results A 61-year-old woman with a medical history significant for metastatic Osteosarcoma was referred to Gastroenterology clinic July 2023 for anemia investigation. Her Osteosarcoma was first diagnosed in the left femur in 2009. She was known for extensive bilateral lung metastasis, subcutaneous metastatic deposits, and distant bone metastasis. She had undergone over 37 surgeries and multiple sessions of radiotherapy. Aside from neoadjuvant and adjuvant chemotherapy for the primary tumor and the first occurrence of lung metastasis, she refused to undergo further cycles of chemotherapy. She had a 60 mg/dl hemoglobin drop from a previous one in December 2023 and intermittent melena. On gastroscopy, she was found to have a 2 cm bleeding mass in the periampullary area. The pathology report of the biopsies was consistent with metastatic osteosarcoma. It showed fragments of ampullary mucosa incorporating a malignant spindle cell neoplasm with a fascicular growth pattern, including scattered osteoclast-like giant cells, morphologically consistent with the known history of metastatic osteosarcoma. Of the 15 cases published, 9 were in patients 27 years old and younger, 3 were in patients 50 and older, and 3 were only available as titles. 50% of cases presented with intussusception while the rest had anemia or melena. The site of metastasis was the jejunum in the majority of patients (58%). Other sites included the ileum, stomach, colon, and esophagus. Only one other patient had periampullary metastasis. All patients had lung metastasis. Conclusions Gastrointestinal metastasis of osteosarcoma remains a rare occurrence. Our case report describes the second case reported in the literature of periampullary metastasis and the first case reported in older patients Funding Agencies None

Diagnostic challenges of gastrointestinal stromal tumour during transurethral resection of the prostate: A case report

Mesenchymal prostate tumours are relatively rare compared to epithelial tumours. To diagnose mesenchymal tumours on transurethral resection of the prostate (TURP) specimen, doctors have to consider a few differential diagnoses, including gastrointestinal stromal tumour (GISTs). We reported a 63 years-old male patient, presented with urinary retention in one week. Based on an initial scan of the abdomen, a large lobulated mass in the pelvic cavity from the prostate pushed up the urinary bladder. Histopathologic examination demonstrated cellular spindle cell neoplastic proliferation, a moderate degree of atypia, and a mitotic count of >5 per 50 high-power fields (HPFs) with a fascicular growth pattern. Immunohistochemically, the tumour had positive expression for CD117 (c-KIT), CD34, and discovered on Gist-1 (DOG-1), while smooth muscle actin (SMA) and S-100 were negative. The pathological report was consistent with a high-risk group of GISTs in the prostate. Subsequent imaging revealed that the tumour mass was centrally located between the rectum and prostate, infiltrating bladder and liver metastases. Comprehensive differential diagnoses of mesenchymal tumours involving the prostate are necessary because of the inadequacy of specific clinical signs, symptoms, and unexpected location. Diagnoses of GISTs was performed based on spindle cell pattern and the positive immunohistochemistry expression for CD117, CD34, and DOG-1. The tumour mass involved in the prostate with spindled morphology should be considered as a GIST, assisted with appropriate immunohistochemistry marker panel. It is a challenge to diagnose the GIST particularly involving the prostate.

Synovial Sarcoma of the Descending Colon: Report of a Rare Case and Review of the Literature

Abstract Introduction/Objective Synovial Sarcoma is a mesenchymal malignancy that occurs primarily in the deep soft tissue near large joints of the extremities in young adults. Synovial sarcoma of the gastrointestinal tract is extremely rare. There is not enough literature to establish a consensus on management and treatment for colorectal synovial sarcoma. Methods/Case Report An 85-year-old male preresented with a positive cologuard test and the colonoscopy revealed a 12 mm polyp in the descending colon. Polypectomy was preformed. Histological examination exhibits spindle cell proliferation with fascicular growth pattern and with small nucleoli. There are collagen deposition, variable size of thick wall vessels and mixed inflammatory cells including lymphocytes, eosinophils and neutrophils in the background. Mitosis are identified. Immunohistochemical stains show tumor cells are negative for CD34, S100, DOG1, CD117, STAT6, Bcl-2, Desmin, and AE1/AE3, and focal positive for EMA, SMA and ALK. Immunohistochemical stain for SS18-SSX fusion protein is positive. Archer fusionplex targeted RNA sequencing (M23-1377) showed SS18:SSX2 fusion. A structural genomic alteration between the SS18 and SSX2 genes is detected [t(18;X)(q12.1;p11.22)]. These findings confirmed the diagnosis of synovial sarcoma. Results (if a Case Study enter NA) NA Conclusion Here we report a rare case of descending colon primary synovial sarcoma. Synovial sarcoma is generally considered as an aggressive and high-grade lesion with metastatic potential and its management is different from other colorectal neoplasms. This case report emphasies a wide differential diagnosis for colorectal lesions and prompt diagnosis and early management is important for better patient outcome.

Primary cutaneous extraskeletal osteosarcoma: a series of 16 cases

Extraskeletal osteosarcoma (EOS) is a high grade soft tissue tumour characterised by the production of malignant osteoid, without attachment/involvement of underlying bone/periosteum. Rarely, EOS presents as a cutaneous tumour. The clinical behaviour of primary cutaneous EOS (PC-EOS) remains incompletely characterised. Herein we present the largest case series of PC-EOS reported to date. Sixteen PC-EOS cases from the archives/consultation files were retrieved (male:female 1:1; age 31-96 years, mean age 66 years). The tumours measured 1-10 cm (mean 3.2 cm) and were located on the lower extremity (7), head (6), upper extremity (2), and trunk (1). They consisted of pleomorphic, spindled-to-epithelioid cells, with fascicular, nodular, or sheet-like growth patterns and foci of malignant osteoid. Immunohistochemistry did not reveal specific lines of differentiation, and there was no evidence of other tumour types. A literature review was conducted to identify all well characterised cases of PC-EOS. A combined analysis of present and past cases was performed to determine overall trends in clinical characteristics and outcomes. The mean follow-up period was 23.9 months, during which 67.5% of patients experienced progression-free survival and 18% of patients died of disease. Rates of local recurrence and metastasis were 10% and 25%, respectively, approximately double past estimates. These data suggest that the prognosis of PC-EOS is less favourable than previously thought. The differential diagnosis includes benign entities (e.g., ossifying pyogenic granuloma) and malignant neoplasms with heterologous osteosarcomatous differentiation (e.g., carcinosarcoma, transdifferentiated melanoma). Wide excision remains the standard of care, and the role of chemotherapy and radiation remains inconclusive. Recognition of this rare entity can facilitate prompt diagnosis and appropriate treatment.

S2125 Short Time Recurrence of Retroperitoneal Desmoid Tumor in Patient With Familial Adenomatous Polyposis

Introduction: A Desmoid Tumor (DT) is a locally invasive, non-metastatic mesenchymal stem cell tumor that typically manifests as a soft tissue mass occurring in muscles, fasciae and aponeuroses. We present a case of a patient with recurrence of a retroperitoneal DT shortly after resection. Case Description/Methods: A 34-year-old male presented with abdominal pain found to have a large (11 × 14.4 * 14 cm) intrabdominal mass. IR transcatheter biopsy of the mass confirmed DT. He underwent bidirectional endoscopy and found to have more than hundred adenomatous colon polyps. Genetic testing confirmed APC mutation. Patient was diagnosed with DT associate with Familial Adenomatous Polyposis (FAP). He underwent radical resection of mesenteric mass and small bowel (20 cm of terminal ileum), omentectomy as well as total colectomy with ileorectal anastomosis. There was no evidence of lymphoid involvement. About 3 months later, he was re-admitted for increased abdominal girth with abdominal pain. MRI scans demonstrated a new, extensive, lobulated soft tissue mass occupying the entire abdominal cavity measuring 23.4 × 12.5 × 24.2 cm. Biopsy of the mass confirmed recurrent DT. Given the large size and proximity to the superior mesenteric artery, the mass was deemed to be unresectable. Patient was initially started on palliative systemic treatment with liposomal Doxorubicin. Due to lack of response, he was then switched to weekly methotrexate and Vinblastine (Figure). Discussion: DTs are rare neoplasms, making up only 0.03% of all neoplasms and 3% of soft tissue tumors. They typically include the abdominal wall, extremities, and mesentery. Although the etiology of DTs is not well known, there are several risk factors that are associated with their occurrence. Genetic syndromes such as FAP and Gardner syndrome have a well-known association with DTs. Other associations include antecedent trauma to the site of the lesion, pregnancy, and female sex. Numerous studies have been done assessing the efficacy of surgery, radiotherapy, and chemotherapy in managing DTs. However, none have shown conclusive benefit. The recurrence rate, particularly following surgical management, has been found to be as high as 77%. Given the lack of definitive management and high recurrence rates, treatment options should likely include combination of both surgical intervention and systemic treatment after discussing options and adverse effects of treatment with the patient.Figure 1.: A, Contrast enhanced CT axial through the lower abdomen demonstrating recurrence of large mass now occupying the majority of the abdominal cavity (black star); B, Spindle cell lesion, with fascicular and loose storiform growth patterns (H&E, 40×) prior to resection; C, Recurrent tumor with pathology demonstrating spindle cell lesion with more edema and/or myxoid stroma.

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. Herein, we report the largest case series of pancreatic desmoid tumors with clinical, cytopathologic, and radiologic correlation.

Vulvar Squamous Cell Carcinoma With Sarcomatoid Features are HPV-independent Lesions: A Subset are Also Associated With TP 53-independent Lesions and Radiation Therapy.

Vulvar squamous cell carcinoma of the vulva (VSCC) with sarcomatoid features is a rare variant characterized by spindle-cell morphology and occasional heterologous elements. They are difficult to evaluate due to rarity and lack unified nomenclature and histopathologic criteria. Eight cases of sarcomatoid VSCC were retrieved from archival electronic medical records from 2013 to 2021. Patients often presented at a mean age of 78-yr-old at stage FIGO (2018) III or above. The mean greatest diameter was 4.5 cm and mean depth of invasion was 11.5 mm. Spindle cells exhibited fascicular, nested, and cord-like growth patterns, though a haphazard arrangement or a mix of patterns was frequently observed. The sarcomatoid component frequently arose in the context of prior conventional VSCC treated with radiation therapy (n=6, 75% and chemotherapy (n=5, 63%) with latency periods of 5.2 and 5.4 yr, respectively. Associated lesions included differentiated vulvar intraepithelial neoplasia (n=4, 50%), lichen sclerosus (n=5, 63%), and vulvar acanthosis with altered differentiation (n=1, 13%). Immunohistochemistry showed that VSCC with sarcomatoid features aberrantly expressed p53 (n=4, 60%) through diffuse overexpression or null-type patterns. P16 was invariably negative in all cases. These findings suggest that VSCC with sarcomatoid features does not arise from the HPV-related carcinogenic pathway, and that a subset may also arise from the TP53-independent pathway. Recognizing sarcomatoid morphology in VSCC is important since it may confer an elevated risk of nodal metastasis and poorer survival. Larger studies are required to assess the etiology and prognostic implications of VSCC with sarcomatoid features.

When an old pigmented lesion becomes serious: the problematic diagnosis of low-grade skin malignancies – Bednar tumor with fibrosarcomatous transformation

Abstract Bednar tumor is a rare cutaneous neoplasm, regarded as a variant of dermatofibrosarcoma protuberans with melanotic colonization and it usually affects young and middle-aged adults or children. This lesion is considered a low-grade malignant tumor, which can be associated with multiple local recurrences after surgical excision. Although a rare phenomenon, these lesions may undergo fibrosarcomatous transformation, which implies a poorer prognosis of the disease, as the tumor has a more locally aggressive behavior and patients might also develop distant metastases. We present the case of a 53-year-old female patient, with no significant medical history, who presented with a subcutaneous nodule on her upper back, for which a wide surgical excision was performed. The gross examination of the specimen showed a solitary protuberant grey-white nodule with a bluish shade and flecked with pigment. The microscopic examination revealed a malignant proliferation with a predominantly fascicular growth pattern, composed of spindle cells with highly pleomorphic nuclei and high mitotic rate, as well as the presence of dendritic cells with abundant melanin. Upon immunohistochemical analysis, the proliferation showed negative staining for CD 34 and AE 1/3, whereas the scattered dendritic cells stained positive with S100 protein. Ki 67 was positive in 15% of the tumor cells and the absence of p53 expression was noted. Thus, the diagnosis of Bednar tumor with fibrosarcomatous transformation was established. The aim of this paper was to gain further knowledge about the histopathological and immunohistochemical features, as well as about the treatment of Bednar tumor, especially considering its rarity.

Fibrosarcoma pada anjing golden retriever di Rumah Sakit Hewan Pendidikan Universitas Airlangga

The dog named Agra (Golden Retriever) is suspected of having an axillary tumor. After surgery and examination of the pathology laboratory, it was found that the dog had fibrosarcoma in the axillaries. Fibrosarcoma is a malignant neoplasm that originates from mesenchymal cells, where the dominant cell histology is fibroblast cells that divide excessively and uncontrollably, can attack local tissues, and can move to other locations in the body (metastatic). The histopathological features of fibrosarcoma have fusiform or spindle-shaped cell fascicular growth patterns. The boundary between cells appears unclear with little cytoplasm and collagen fibers form parallel webbing. Grading histology is mainly based on the degree of cellularity, cell differentiation, mitotic features, and the amount of collagen produced by the cell necrosis. Surgery until now is the first and foremost thing in tumor therapy. Benign tumors can be removed with various surgical techniques depending on the location of the tumor. As for malignant tumors, surgery can be carried out by following other additional therapies to inhibit tumor growth.

BIPHENOTYPIC SINONASAL SARCOMA OF THE NASOPHARYNX: CASE REPORT

Biphenotypic sinonasal sarcoma is a rare and recently recognized entity. It is a low-grade sarcoma which exhibits both neural and myogenic differentiation. The objective of this study is to report a case of a 25-year-old male patient with nasal congestion and bleeding. Computed tomography showed a tumor mass in the nasopharynx. Microscopic analysis showed a cellular proliferation of spindle cells, forming mainly a herringbone-like fascicular growth pattern. Immunohistochemical analysis showed focal positivity for S100, alpha-smooth muscle actin, and calponin, and negativity for desmin, SOX 10, and FXIIIA. We present an uncommon case of biphenotypic sinonasal sarcoma of the nasopharynx and emphasize the importance of recognizing rare entities with impact on the health of these patients.

Clinicopathological features and prognosis of ALK-positive Spitz tumors

Objective: To investigate the clinicopathologic features and prognosis of ALK-positive Spitz tumors. Methods: Thirteen patients with ALK-positive Spitz tumors diagnosed at Shanghai Cancer Center, Fudan University from October 2016 to December 2017 were collected. All cases were routinely evaluated histopathological features in HE staining and detected ALK protein expression by immunohistochemistry. The ALK fusions of 7 cases were confirmed by fluorescence in situ hybridization (FISH).Follow-up data was collected. Results: The age of patients including 2 males and 11 females ranged from 4 to 47 years (mean 25 years). 12 patients were diagnosed with atypical Spitz tumors and 1 patient was diagnosed with Spitz nevus. Clinically, most lesions presented as papules or nodules, while a few lesions presented as plaques. Histologically, most tumors were exophytic (9/13). More than half of the tumors were amelanotic and the junctional component was mainly composed of melanocytic nests. Kamino bodies were not found. The bases of the tumors were mainly wedge-shaped (5/13) and flat (7/13). Eight tumors displayed mixed cell types, while 5 tumors were composed of only spindle cells. All the tumors showed a plexiform and/or intersecting fascicular growth pattern, and perineural extension was observed in 3 tumors. ALK immunohistochemistry showed diffuse and intense cytoplasmic staining in 13 cases, and 7 of them were detected by FISH to confirm the presence of ALK fusions. All patients were followed up for 7 to 21 months (median=12), with no recurrence or lymph node dissemination. Conclusions: Spitz tumors with ALK fusions have their special histopathologic features.ALK fusions mainly occur in Spitz nevi and atypical Spitz tumors. The follow-up data of the existing literatures and our research indicates that the prognosis of ALK-positive Spitz tumors may be good.

Mucosal Schwann cell hamartomas do occur the gastric mucosa \u2013 report of two cases mimicking fundic gland polyps

Mucosal Schwann cell hamartomas (MSCHs) are recently characterized benign spindle cell lesions of the colon and rectum. There is only one report of MSCHs in the stomach (antrum). Herein, we present the first reports of MSCHs occurring in the fundic mucosa as lesions that endoscopically mimicked a typical fundic gland polyp. Case 1. A 56-year-old woman sought medical attention due to epigastric pain. A small polypoid lesion in the fundic mucosa was removed with an endoscopic impression of a fundic gland polyp. Case 2. A 66-year-old man sought medical attention due to epigastric pain. The patient underwent antral and corporal biopsies that showed mild non-active gastritis without Helicobacter pylori infection. Small polypoid lesions in the fundic mucosa were seen; one was removed with an endoscopic impression of the fundic gland polyp. At the microscope, both lesions were entirely intramucosal, ill-defined spindle cell aggregations, suggesting a fascicular growth pattern. Both lesions were strongly and diffusely positive for S100. Awareness of this lesion is relevant to avoid the diagnosis of other benign spindle cell lesions that are associated with familial syndromes.

A case of a malignant peripheral nerve sheath tumor in a guinea pig

Here, we describe the clinical and histopathological characteristics of a malignant peripheral nerve sheath tumor (MPNST) extending from the dorsal subcutis to the periphery of the spine in a female guinea pig aged 3 years 7 months. The patient presented with pleural and blood-like pericardial effusion and died. The tumor had invaded the spine and the surrounding muscles and had grown in hypercellular and hypocellular arrangements of round, broad-spindle, and elongated-spindle cells. We observed a fascicular growth pattern, nuclear palisading, and perivascular accumulations of cells that responded positively to anti-S100, sox10, and CD56 antibodies. This is the first report of a MPSNT in a guinea pig.

Establishment and Characterization of a Novel Human Clear-cell Sarcoma of Soft-tissue Cell Line, RSAR001, Derived from Pleural Effusion of a Patient with Pleural Dissemination.

Clear cell sarcoma (CCS) of soft tissue is exceedingly rare and frequently exhibits aggressive behavior. Toward the goals of improving the aggressive course and poor prognosis of CCS, and establish new therapeutic methods, molecular genetic and biological characterizations of CCS are required. A new human CCS cell line (designated RSAR001) was established from the pleural effusion of a 44-year-old man with multiple lung metastases and pleural dissemination. The cell line and its xenograft were characterized including their morphology, immunohistochemistry, cytogenetic analysis, reverse transcription-polymerase chain reaction, direct sequencing analysis, and fluorescence in situ hybridization analysis. The cell line has been maintained for over 12 months with more than 50 passages. RSAR001 cells exhibited a fascicular or diffuse growth pattern of short spindle- or oval-shaped cells with clear cytoplasm in heterotransplanted tumor, that was similar to the primary tumor. Immunophenotypically, RSAR001 cells in vitro and in vivo exhibited almost the same characteristics as the primary tumor. Cytogenetic analyses revealed a translocation, t(12;22)(q13;q12). Reverse transcription-polymerase chain reaction and direct sequencing analysis detected transcripts of the Ewing sarcoma breakpoint region 1-activating transcription factor 1 (EWSR1-ATF1) type 1 fusion gene. Fluorescence in situ hybridization using a break-apart probe for the EWSR1 gene on 22q12 showed a rearrangement. These findings indicate that the RSAR001 cell line harbors EWSR1-ATF1 type 1 chimeric fusion gene, which is specific to CCS. RSAR001 cells might be useful for investigating biological behaviors and developing new treatments such as molecular-targeting antitumor drugs or immunological drugs for CCS.

Inflammatory Myofibroblastic Tumor in Female Genital Tract.

Inflammatory myofibroblastic tumor is a mesenchymal neoplasm of low malignant potential. It was first described in lung, but is known to occur in many extrapulmonary sites including female genital organs, most commonly the uterus. It has a high recurrence rate and a low risk for metastasis. A more recently described aggressive variant, epithelioid myofibroblastic sarcoma with a predilection for the abdominal cavity of males, has also been recently reported to occur in the ovary. This tumor is composed of spindled and epithelioid myofibroblasts in a variably myxoid stroma and commonly shows a fascicular growth pattern with positive staining for desmin, smooth muscle actin, and CD10, which may mimic a smooth muscle or endometrial stromal neoplasm. In the female genital tract it has the potential for being misdiagnosed as a leiomyoma, endometrial stromal tumor, or as a myxoid leiomyosarcoma, resulting in undertreatment or overtreatment. It harbors rearrangements in the ALK gene, resulting in abnormal expression of ALK protein. Immunostaining for ALK is a helpful diagnostic tool. To provide a brief review of clinical, histologic, immunohistochemical, and molecular features of inflammatory myofibroblastic tumor with emphasis on possible diagnostic pitfalls in the female genital tract. Review of pertinent literature on inflammatory myofibroblastic tumor occurring in the female genital tract and personal experience of the authors. Inflammatory myofibroblastic tumor in the female genital tract can mimic other more common benign and malignant tumors like leiomyoma, leiomyosarcoma, and endometrial stromal sarcoma. Familiarity with clinical and histologic features and use of ALK immunostaining can be critical for correct diagnosis.

First Reported Case of Endoscopic Ultrasound-Guided Core Biopsy Yielding Diagnosis of Primary Adrenal Leiomyosarcoma

Introduction Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) or core biopsy (EUS-CB) is a safe, effective modality for sampling adrenal lesions [1]. We present the first case of primary adrenal leiomyosarcoma diagnosed by EUS-CB. Case Description 50 year old male presented with abdominal pain and weight loss for a year. Physical exam and labs were normal. Computed Tomography (CT) abdomen showed an 8.1 cm heterogeneous left adrenal mass and several hypodense liver lesions concerning for metastatic disease. Positron Emission Tomography (PET) scan showed FDG avid left adrenal mass and mildly avid lung and liver lesions suggestive of metastatic disease. Pheochromocytoma was ruled out with negative urine metanephrines and catecholamines. There was no clinical evidence of Cushing's Syndrome. Adrenal cortical carcinoma was considered but as there was no evidence of precursor steroids being produced, EUS-CB of the left adrenal mass was performed. This revealed a spindle cell neoplasm with extensive necrosis. Tumor cells stained positive for desmin, cytokeratin Mak6, and S-100, and negative for CD34 and chromogranin. Based on these findings, a diagnosis of primary leiomyosarcoma of the left adrenal gland was made. Adriamycin and olaratumab with palliative radiation for pain was then initiated as metastatic disease precluded surgery. Discussion Primary adrenal leiomyosarcomas are extremely rare, with less than 35 cases reported [2]. They grow rapidly, do not produce any adrenal hormonal derangements, and lack characteristic tumor markers or imaging findings, making preoperative diagnosis difficult. Diagnosis is usually made on surgical resection or autopsy [2]. To our knowledge, this is the first case of primary adrenal leiomyosarcoma diagnosed by EUS. In our case, in which metastatic disease was noted, this diagnosis affected clinical management and prevented further invasive procedures.Figure: CT abdomen showing 8.1 cm heterogeneous left adrenal mass.Figure: EUS showing irregular, hypoechoic left adrenal mass measuring 63 x 44 mm.Figure: Spindle cell neoplasm with extensive tumor necrosis (A). High power view showing fascicular growth pattern and cytological pleomorphism (B).

Phenotypic variation of thymic epithelial cells and partial spontaneous regression in thymoma of a cow

Thymoma was recognized in a 12-year-old Holstein dairy cow presenting with no significant clinical signs. The animal was conventionally slaughtered at an abattoir and, on postmortem examination, a spherical tumor mass was found in the anterior region of the mediastinum. Histologically, the tumor was fibrously encapsulated and exhibiting varying-sized cystoid cavities containing serous fluid and necrotic and hemorrhagic foci. No architectural features showing distinct characteristics to a sufficient degree to allow identification of the thymus or other organs could be seen. The tumor showed diffuse solid sheet-like or nodular patterns of proliferation and consisted of a dual cell population: one was neoplastic epithelial cells that were immunohistochemically positive for cytokeratin, and the other was T lymphocytes that exhibited positive immunohistochemical staining with CD3. This finding enabled a diagnosis of mixed thymoma to be made. Neoplastic epithelial cells represented a wide spectrum of phenotypic expression, including (1) spindle shaped cells with a chiasmus-like, interlacing fascicular, or storiform growth pattern; (2) small, round to oval cells with scant cytoplasm showing indistinct boundary of cells; (3) large cells arranged in a solid sheet-like pattern; (4) vacuolated cells similar to signet ring cells; (5) clear cells that had defined cell membranes; and (6) occasional formation of micronodules composed of neoplastic epithelial cells. In addition, some areas of the tumor exhibited features of partial spontaneous regression characterized by collapse or disintegration of tumor tissues in close association with fibrocollagenous connective tissue deposition. Even if the morphology of thymic epithelial cells in thymoma is known to display variable appearance, it is likely to be unusual that, in the current bovine case, such thymic epithelial cells exhibited a wider spectrum of phenotypic expression within a single tumor. This salient histomorphological heterogeneity shown by thymic epithelial cells might have presumably been associated with innate characteristics specific to pluripotent thymic epithelial cells during thymoma tumorigenesis.

Malignant gastrointestinal neuroectodermal tumor: A case report and review of the literature.

Malignant gastrointestinal neuroectodermal tumor (GNET) is a rare soft tissue sarcoma, previously referred to as clear cell sarcoma-like gastrointestinal tumor (CCSLGT) and also commonly reported in the literature as clear cell sarcoma of the gastrointestinal tract (CCS-GI). The current study reports a case of GNET arising in the stomach of a 17-year-old male, who presented with symptoms of fatigue, anemia and low temperature. Examination with positron emission tomography-computed tomography revealed a soft tissue mass in the gastric antrum. Subsequently, radical distal gastric resection was performed, and the mass measured 6.0×4.0×3.5 cm3. Histopathological analysis revealed that the tumor cells were arranged in nests and focally formed fascicular, pseudopapillary, pseudoalveolar and rosette-like growth patterns. Osteoclast-like giant cells were also observed. Immunohistochemically, the tumor cells were positive for S-100 protein, vimentin and BCL-2, and negative for HMB45, Melan-A, CD117, CD34 and CD99. Additionally, the osteoclast-like giant cells were positive for CD68. Fluorescence in situ hybridization demonstrated EWSR1 gene rearrangement. After 10 months of follow-up, no evidence of recurrence or metastasis was observed. As GNET is currently classified differently and under various names in the literature, the information provided by this case study and review is predicted to be useful towards the accurate diagnosis, treatment and prognosis of this rare tumor type.