Soft Tissue Tumor Immunohistochemistry Update: Illustrative Examples of Diagnostic Pearls to Avoid Pitfalls

Cardiac Magnetic Resonance to Predict Cardiac Mass Malignancy: The CMR Mass Score

BACKGROUND

Multimodality imaging is currently suggested for the noninvasive diagnosis of cardiac masses. The identification of cardiac masses' malignant nature is essential to guide proper treatment. We aimed to develop a cardiac magnetic resonance (CMR)-derived model including mass localization, morphology, and tissue characterization to predict malignancy (with histology as gold standard), to compare its accuracy versus the diagnostic echocardiographic mass score, and to evaluate its prognostic ability.

METHODS

Observational cohort study of 167 consecutive patients undergoing comprehensive echocardiogram and CMR within 1-month time interval for suspected cardiac mass. A definitive diagnosis was achieved by histological examination or, in the case of cardiac thrombi, by histology or radiological resolution after adequate anticoagulation treatment. Logistic regression was performed to assess CMR-derived independent predictors of malignancy, which were included in a predictive model to derive the CMR mass score. Kaplan-Meier curves and Cox regression were used to investigate the prognostic ability of predictors.

RESULTS

In CMR, mass morphological features (non-left localization, sessile, polylobate, inhomogeneity, infiltration, and pericardial effusion) and mass tissue characterization features (first-pass perfusion and heterogeneity enhancement) were independent predictors of malignancy. The CMR mass score (range, 0-8 and cutoff, ≥5), including sessile appearance, polylobate shape, infiltration, pericardial effusion, first-pass contrast perfusion, and heterogeneity enhancement, showed excellent accuracy in predicting malignancy (areas under the curve, 0.976 [95% CI, 0.96-0.99]), significantly higher than diagnostic echocardiographic mass score (areas under the curve, 0.932; P=0.040). The agreement between the diagnostic echocardiographic mass and CMR mass scores was good (κ=0.66). A CMR mass score of ≥5 predicted a higher risk of all-cause death (P<0.001; hazard ratio, 5.70) at follow-up.

CONCLUSIONS

A CMR-derived model, including mass morphology and tissue characterization, showed excellent accuracy, superior to echocardiography, in predicting cardiac masses malignancy, with prognostic implications.

Exploring Solitary Fibrous Tumors at a Tertiary Cancer Center: Clinicopathological and Immunomorphologic Profile

Background Solitary fibrous tumor (SFT) is a distinct fibroblastic tumor that can occur at any anatomical site and can manifest a variety of histopathological features. NAB2-STAT6 gene fusion has recently emerged as a sensitive and specific molecular marker and its surrogate on immunohistochemistry, STAT6 has also displayed considerable efficacy. Nevertheless, its histologic diversity can result in diagnostic challenges, especially when classic features are not apparent. Methods A retrospective study was conducted at a tertiary cancer centre in North India over 3 years to document the clinicopathologic and immunomorphologic profile of SFTs. Immunohistochemical analysis of BCOR and p53 were gauged additionally and patients were stratified according to Modified Demicco and Salas criteria for risk of metastasis. Results Sixteen patients of SFT were identified, affecting middle-aged men and women equally. Though lung/pleura are known to be involved commonly, SFT affects other sites such as the kidney, brain, buccal mucosa, liver, and penis as well. The majority endured localized disease while a lesser number suffered locoregional/distant spread. Two patients revealed features of a malignant profile. Risk stratification according to the Modified Demicco and Salas criteria evinced comparable results. No discernible relationship however was highlighted between the immunohistochemical expression of BCOR, p53, and any significant SFT parameter. Conclusion Although SFTs are very rare substantially benign mesenchymal neoplasms, pathologists must be conversant with their histological diversity and be vigilant of their malignant attributes. The worth of STAT6 immunohistochemistry for precise diagnosis and long-term studies for delineating clinical behavior cannot be overemphasized.

HCC-Check: A Novel Diagnostic Tool for Early Detection of Hepatocellular Carcinoma Based on Cytokeratin-1 and Epithelial Membrane Antigen: A Cross-Sectional Study

Background: Hepatocellular carcinoma is frequently diagnosed in advanced stages, leading to a poorer prognosis. Therefore, early diagnosis and identification of biomarkers may significantly improve outcomes. Methods: This cross-sectional study enrolled 486 participants distributed among 3 groups: F1 to F3 = 184, F4 = 183, and hepatocellular carcinoma = 119. Liver fibrosis staging was performed using FibroScan, while imaging features were used for hepatocellular carcinoma detection. Epithelial membrane antigen and cytokeratin-1 levels in serum were quantified through Western blot and ELISA, respectively. Results: Patients diagnosed with hepatocellular carcinoma exhibited significantly elevated levels of epithelial membrane antigen and cytokeratin-1 compared to non-hepatocellular carcinoma patients, with a highly significant statistical difference (P < .0001). Epithelial membrane antigen demonstrated diagnostic performance with an area under the curve of 0.75, a sensitivity of 69.0%, and a specificity of 68.5%. Cytokeratin-1 for the identification of hepatocellular carcinoma showed a sensitivity of 79.0% and a specificity of 81.4%, resulting in an area under the curve of 0.87. The developed HCC-Check, which incorporates epithelial membrane antigen, cytokeratin-1, albumin, and alpha-fetoprotein, displayed a higher area under the curve of 0.95 to identify hepatocellular carcinoma, with a sensitivity of 89.8% and a specificity of 83.9%. Notably, HCC-Check values exceeding 2.57 substantially increased the likelihood of hepatocellular carcinoma, with an estimated odds ratio of 50.65, indicating a higher susceptibility to hepatocellular carcinoma development than those with lower values. The HCC-Check diagnostic test exhibited high precision in identifying patients with hepatocellular carcinoma, particularly those with small tumor sizes (<5 cm) and a single nodule, as reflected in area under the curve values of 0.92 and 0.85, respectively. HCC-Check was then applied to the validation study to test its accuracy and reproducibility, showing superior area under the curves for identifying different stages of hepatocellular carcinoma. These outcomes underscore the effectiveness of the test in the early detection of hepatocellular carcinoma. Conclusion: The HCC-Check test presents a highly accurate diagnostic method for detecting hepatocellular carcinoma in its early stages.

The Expression of Mucin-4 (MUC4) in Sarcomas Apart From Sclerosing Epithelioid Fibrosarcoma and Low-Grade Fibromyxoid Sarcoma

Background Low-grade fibromyxoid sarcoma (LGFMS) and sclerosing epithelioid fibrosarcoma (SEF) are two rare but aggressive soft tissue sarcomas that can be difficult to distinguish due to histopathological similarities. The present study examines the diagnostic capacities of mucin-4 (MUC4), a transmembrane mucin, in identifying different types of sarcomas and broadens its evaluation to include a wide range of sarcomas. Methods Immunohistochemical (IHC) examination of tissue samples from various sarcomas was performed using a mouse anti-MUC4 monoclonal antibody. IHC was conducted on 4-mm thick formalin-fixed paraffin-embedded tissue sections after pressure cooker antigen retrieval with a mouse anti-MUC4 monoclonal antibody. Results MUC4 was shown to be highly expressed in SEF (n=13) and LGFMS (n=10), while focal positivity in synovial sarcoma (n=1). Other sarcomas, such as malignant peripheral nerve sheath tumors, fibrosarcoma, leiomyosarcoma, liposarcoma, and myxofibrosarcoma, exhibited no expression (n=0). These findings are consistent with previous research and support MUC4 specificity as a SEF and LGFMS marker. This study provides information on the diagnostic efficacy of MUC4, particularly in the context of certain subtypes. It not only helps our understanding of these unique instances, but it also provides context for histopathological and IHC findings in soft tissue sarcoma. Furthermore, this study investigates the influence of age and gender on MUC4 expression in a range of sarcomas, which was typically understudied in the literature and found no relation with expression of MUC4. Conclusion In conclusion, this study adds to our understanding of soft tissue sarcomas by emphasizing the crucial role of MUC4 in certain sarcoma subtypes while acknowledging the complex variety of the sarcoma landscape. Further research is needed to understand the molecular mechanism that governs marker expression patterns, as well as the therapeutic implications.

SS18-SSX Expression in a Contemporary Cohort of Primary Renal Synovial Sarcoma: A Multi-Institutional Experience of Fourteen Patients

Primary renal synovial sarcoma is a rare aggressive mesenchymal neoplasm of the kidney that accounts for less than 1% of renal sarcomas. Herein, we describe the clinicopathologic and molecular findings of 14 renal synovial sarcoma patients in one of the largest case series to date and to our knowledge, the only renal synovial sarcoma series to use novel SS18-SSX IHC. Clinicopathologic, IHC, molecular, management, and follow-up data were reviewed and analyzed. Macroscopically, the tumors had either homogeneous, tan-white, and solid (n = 10), variegated and solid (n = 3), or variegated and solid-cystic (n = 1) cut surfaces. Spindle cell (n = 10), round cell (n = 3), and round to epithelioid morphologies (n = 1) were observed. SS18-SSX IHC was positive in all 14 tumors (diffuse, n = 10; multifocal, n = 2; focal, n = 2). All the tumors harbored SS18::SSX1/2 gene rearrangement. Metastases to the liver, brain, and lung (n = 1); liver and bone (n = 1); liver and diaphragm (n = 1) were identified. Adjuvant chemotherapy was administered in 11/12 patients. Follow-up was available for 10 patients (time period range: 5 to 24 months). Four patients died of disease, and six patients are alive with no recurrence or metastasis. As SS18-SSX IHC showed an excellent concordance with the FISH results, this may reliably be used in the IHC panel of spindle/round cell sarcomas of the kidney and as a molecular surrogate for renal synovial sarcoma, particularly in a resource-limited setting. Also, the tumors with focal SS18-SSX expression had lower break apart signals in the FISH assay (19% and 23% in two tumors with focal SS18-SSX IHC positivity).

Intermediate filament proteins are reliable immunohistological biomarkers to help diagnose multiple tissue-specific diseases

Cytoskeletal networks are proteins that effectively maintain cell integrity and provide mechanical support to cells by actively transmitting mechanical signals. Intermediate filaments, which are from the cytoskeleton family and are 10 nanometres in diameter, are unlike actin and microtubules, which are highly dynamic cytoskeletal elements. Intermediate filaments are flexible at low strain, harden at high strain and resist breaking. For this reason, these filaments fulfil structural functions by providing mechanical support to the cells through their different strain-hardening properties. Intermediate filaments are suitable in that cells both cope with mechanical forces and modulate signal transmission. These filaments are composed of fibrous proteins that exhibit a central α-helical rod domain with a conserved substructure. Intermediate filament proteins are divided into six groups. Type I and type II include acidic and basic keratins, type III, vimentin, desmin, peripheralin and glial fibrillary acidic protein (GFAP), respectively. Type IV intermediate filament group includes neurofilament proteins and a fourth neurofilament subunit, α-internexin proteins. Type V consists of lamins located in the nucleus, and the type VI group consists of lens-specific intermediate filaments, CP49/phakinin and filen. Intermediate filament proteins show specific immunoreactivity in differentiating cells and mature cells of various types. Various carcinomas such as colorectal, urothelial and ovarian, diseases such as chronic pancreatitis, cirrhosis, hepatitis and cataract have been associated with intermediate filaments. Accordingly, this section reviews available immunohistochemical antibodies to intermediate filament proteins. Identification of intermediate filament proteins by methodological methods may contribute to the understanding of complex diseases.

Primary Epithelioid Sarcoma of the Conchal Bowl in a 64-Year-Old Male: A Case Report and Review of the Literature

ABSTRACT

Epithelioid sarcoma (ES) is a distinctive malignant mesenchymal neoplasm with atypical epithelioid cells palisading around a central zone of necrosis. ES is a rare entity even in soft tissue pathology. Immunohistochemically, tumors usually show diffuse epithelial membrane antigen and cytokeratin expression and loss of nuclear INI1 (SMARCB1) expression. Here, we report a case of a 64-year-old man with ES arising in the left conchal bowl. Given the clinical presentation including patient's age, sun-exposed area of skin, and slow-growing, asymptomatic, small pink pearly papule, this patient was initially misdiagnosed with basal cell carcinoma clinically and treated with topical imiquimod at an outside facility. The lesion continued to grow and eventually became symptomatic despite the treatment after which biopsy was obtained. Despite the unusual anatomic site and the patient's age, the microscopic and immunohistochemical findings were characteristic of conventional-type ES. Our case shows that ES can arise in rare locations and in older adults where it may be more easily misdiagnosed clinically and pathologically as a nonmelanoma skin cancer.

Metastatic sarcomas to pleural effusion: a 10-year large tertiary care center experience with emphasis on clinical features and cytomorphologic characteristics

INTRODUCTION

Metastatic sarcomas to pleural effusion are extremely rare, accounting for <1% of all malignant pleural effusions. We aim to present our experience with pleural effusion specimens containing metastatic sarcomas over a 10-year period.

METHODS

We performed a 10-year retrospective search of cytopathology archives to identify all pleural effusions that were involved by metastatic sarcoma. All available cytopathology and surgical pathology specimens were retrieved and reviewed.

RESULTS

Twenty-eight pleural fluids from 22 patients with metastatic sarcoma were identified in our search. The patients' ages ranged from 12 to 73 years. The pleural fluid volumes ranged from 10 to 1500 ml. Rhabdomyosarcoma was the most commonly encountered metastatic sarcoma to pleural effusion (n = 7). Other metastatic sarcomas were as follows: epithelioid angiosarcoma (n = 4), Ewing sarcoma (n = 3), clear cell sarcoma (n = 2), high grade conventional osteosarcoma (n = 2), undifferentiated pleomorphic sarcoma (n = 1), epithelioid sarcoma, proximal type (n = 1), dedifferentiated liposarcoma (n = 1), and conventional chondrosarcoma (n = 1). The time between initial diagnosis and effusion varied from 3 months to 25 years. Two patients are alive with disease at 6 and 21 months of follow-up. All other patients were dead of disease and the survival after a malignant pleural effusion ranged from <1 month to 18 months.

CONCLUSIONS

Metastatic bone and soft tissue sarcomas to pleural effusions are rare and their cytologic features can be mistaken for carcinoma, melanoma, or mesothelioma. Careful review of the patient's medical history, comparison of the previous pathology and the use of ancillary studies are crucial for the evaluation of pleural effusions involved by metastatic sarcomas.

Giant retroperitoneal liposarcoma measuring 27 × 29 × 36 cm: a case report

Retroperitoneal tumors are rare neoplasms that can reach great dimensions due to a slow growth pattern. Although these tumors rarely metastasize, they have a great risk of recurrence, and majority of times these lesions are a challenge for the surgeon. We report the case of a 63-year-old woman who presented with symptoms of large bowel obstruction and was diagnosed with a large heterogenous mass located in the retroperitoneal space. The fine needle biopsy revealed the histology of liposarcoma. The purpose of this article is to report our approach in management of this kind of tumor. Tumor size (27.1 × 29.1 × 36.1 cm) and involvement to the adjacent organs was a challenge for us in order to reach safe oncological margins. In these cases, the risk of recurrence is high; therefore, the patient should be screened at 6, 12 and 24 months post procedure. Chemotherapy or radiotherapy for this tumor is not yet defined, and if operable, surgery is the treatment of choice.

The clinicopathological challenges of symptomatic and incidental pulmonary hamartomas diagnosis

Pulmonary hamartomas (PHs) are the most common benign lung tumors. Usually, they are asymptomatic and incidentally discovered during assessment for other diseases or during the autopsy exam. In this context, we have performed a retrospective analysis of surgical resections in a 5-year series of patients diagnosed with PHs in the Clinic of Pulmonary Diseases, Iaşi, Romania, aiming to evaluate their clinicopathological features. A total of 27 patients with PH (40.74% males and 59.26% females) were evaluated. 33.33% of patients were asymptomatic, while the others exhibited variable symptoms, such as chronic cough, dyspnea, chest pain or weight loss. In most cases, PHs presented as solitary nodules, predominantly disposed in the right upper lobe (40.74% of cases), followed by the right lower lobe (33.34%), and left lower lobe (18.51%). The microscopic examination revealed a mixture of mature mesenchymal tissue, such as hyaline cartilage, adipose tissue, fibromyxoid tissue, and smooth muscle bundles, in variable proportions, associated with clefts of entrapped benign epithelium. A dominant adipose tissue component was observed in one case. PH was associated with a history of extrapulmonary cancer diagnosis, in one patient. Although considered benign lung tumors, PHs diagnosis and therapy may be challenging. Having in mind the possibility of recurrence or their occurrence as a part of specific syndromes, PHs should be thoroughly investigated for an appropriate patients' management. Their complex significance and the correlation with other types of lesions, including malignancies, may be further studied, by more extensive studies of surgical and necroptic cases.

Investigating the role of signal transducer and activator of transcription 3 in feline injection site sarcoma

BACKGROUND

Feline injection-site sarcomas (FISSs) are malignant mesenchymal tumors of different histotypes. The pathogenesis of FISS has been correlated with chronic inflammation, resulting in neoplastic transformation. Activation of the Janus kinase-signal transducer and activator of transcription 3 (STAT3) have been demonstrated to play a critical role in tumor development by regulating signaling pathways involved in cell proliferation, survival, metastasis, and angiogenesis in human medicine. To characterize the role of STAT3 in FISS, we first detected STAT3 and phosphorylated STAT3 in formalin-fixed and paraffin-embedded (FFPE) FISS tissues using immunohistochemical staining.

RESULTS

STAT3 was detected in 88.9% (40/45) of FISS cases, and phosphorylated STAT3 was detected in 53.3% (24/45) of cases. However, the expression levels of both forms of STAT3 were not correlated with tumor grade. To study the role of STAT3 in tumor survival, two primary cells derived from FISSs of two cats exhibiting consistent immunophenotypes with their parental FFPE tissues were established. A dose-dependent inhibitory effect on cell proliferation was observed in both primary FISS cells treated with the STAT3 inhibitor, 5-hydroxy-9,10-dioxo-9,10-dihydroanthracene-1-sulfonamide.

CONCLUSIONS

The STAT 3 may play an important role in the tumorigenesis of FISS and be a potential molecular therapeutic target for FISS.

Paediatric gingival extra-axial chordoma: an extremely rare entity

Extra-axial chordomas are rare malignant tumours. As a subcategory of axial chordomas, these tumours arise outside the axial skeleton. This report describes the case of a 13-year-old male patient with a gingival mass in the left upper jaw, who was referred to Hannover Medical School with a preliminary diagnosis of a calcifying epithelial odontogenic tumour (CEOT). Pathological examination of the enucleated tumour led to the final diagnosis of a chordoma. Thereafter, a stepwise radical resection was performed with the aim of complete resection of the tumour with wide safety margins. The main tumour mass was found to be located on the maxillary gingiva, with focal infiltration into the maxillary bone. Following resection, reconstruction was performed with a free latissimus dorsi flap. Follow-up after 1 year revealed no signs of recurrence or metastasis. This case highlights that although extremely rare, extra-axial chordoma may occur at sites distant from the midline and as such must be included in the differential diagnosis of bone and soft tissue tumours in the maxillofacial region.

Spindle cell lesions of the breast: a diagnostic approach

Spindle cell lesions of the breast comprise a heterogeneous group of lesions, ranging from reactive and benign processes to aggressive malignant tumours. Despite their rarity, they attract the attention of breast pathologists due to their overlapping morphological features and diagnostic challenges, particularly on core needle biopsy (CNB) specimens. Pathologists should recognise the wide range of differential diagnoses and be familiar with the diverse morphological appearances of these lesions to make an accurate diagnosis and to suggest proper management of the patients. Clinical history, immunohistochemistry, and molecular assays are helpful in making a correct diagnosis in morphologically challenging cases. In this review, we present our approach for the diagnosis of breast spindle cell lesions, highlighting the main features of each entity and the potential pitfalls, particularly on CNB. Breast spindle cell lesions are generally classified into two main categories: bland-appearing and malignant-appearing lesions. Each category includes a distinct list of differential diagnoses and a panel of immunohistochemical markers. In bland-appearing lesions, it is important to distinguish fibromatosis-like spindle cell metaplastic breast carcinoma from other benign entities and to distinguish fibromatosis from scar tissue. The malignant-appearing category includes spindle cell metaplastic carcinoma, stroma rich malignant phyllodes tumour, other primary and metastatic malignant spindle cell tumours of the breast, including angiosarcoma and melanoma, and benign mimics such as florid granulation tissue and nodular fasciitis.

Recurrent Fusion of the GRB2 Associated Binding Protein 1 (GAB1) Gene With ABL Proto-oncogene 1 (ABL1) in Benign Pediatric Soft Tissue Tumors

BACKGROUND/AIM

Fusions of the ABL proto-oncogene 1 gene (ABL1 in 9q34) are common in leukemias but rare in solid tumors. The most notable is the t(9;22)(q34;q11)/BCR-ABL1 coding for a chimeric tyrosine kinase. We herein report an ABL1-fusion in a pediatric tumor.

MATERIALS AND METHODS

G-banding, fluorescence in situ hybridization, reverse transcription polymerase chain reaction and Sanger sequencing were performed on a soft tissue perineurioma found in the left musculus erector spinae of a child.

RESULTS

A der(4)t(4;9)(q31;q34) and a fusion of the GRB2 associated binding protein 1 (GAB1 in 4q31) gene with ABL1 were found. A literature search revealed 3 more cases with similar genetic and clinicopathological characteristics: a soft tissue perineurioma with t(2;9;4)(p23;q34;q31) and ABL1 rearrangement, a soft tissue angiofibroma with a GAB1-ABL1 chimeric gene, and a solitary fibrous tumor carrying a der(4)t(4;9)(q31.1;q34).

CONCLUSION

GAB1-ABL1 is a recurrent fusion gene in benign pediatric tumors.

Small Round Cell Tumors of Soft Tissue and Bone

CONTEXT.—

Small round cell tumors of soft tissue and bone constitute a divergent group of neoplasms. These lesions often demonstrate overlapping clinical and radiologic characteristics and share histomorphologic and sometimes immunophenotypic similarities, but they typically have diverse prognostic outcomes, thus warranting different clinical management. Recent advances in molecular and cytogenetic techniques have identified a number of novel molecular alterations contributing to the diversity of these lesions. This state-of-the-art knowledge has enhanced our understanding of these diseases.

OBJECTIVE.—

To provide an overview of the current concepts in the classification and diagnosis of small round cell tumors of soft tissue and bone, focusing on salient histologic features, key immunophenotypic characteristics, and recent molecular genetic advancements.

DATA SOURCES.—

Data were obtained from pertinent peer-reviewed English-language literature and firsthand experience from the authors as practicing bone and soft tissue pathologists.

CONCLUSIONS.—

Immunohistochemistry plays a vital role in rendering a specific diagnosis or narrowing the differential diagnosis in small round cell tumors of soft tissue and bone. Molecular genetic studies are often needed, especially for those lesions with unusual histologic features, an uncommon immunoprofile, and/or unusual clinical presentation. Accurate diagnosis of these tumors necessitates recognition of salient histologic features, judicious and astute use of ancillary studies, and correlation with the clinical and radiologic characteristics to guide clinical decision-making.

Embryonal Rhabdomyosarcoma Presenting as Lung Metastasis in an Adult: An Uncommon Presentation

Rhabdomyosarcoma (RMS) is one of the most common soft tissue sarcomas of adolescents and young adults. Histologically, rhabdomyosarcoma is classified into embryonal, alveolar, pleomorphic, and spindle cell/sclerosing rhabdomyosarcomas with further subcategorization. More than 50% of embryonal rhabdomyosarcoma occur within head and neck. The retroperitoneum and pelvis are less common sites of involvement. Embryonal rhabdomyosarcomas affect mainly, but not exclusively, children between birth and 15 years of age. Alveolar rhabdomyosarcoma tends to affect older patients. The usual metastatic sites include lung, lymph nodes, and bone marrow. We are presenting a case of a 25-year-old male patient with symptoms of breathlessness, easy fatigability, and weight loss. On chest imaging, there were multiple lung nodules. A primary diagnosis of undifferentiated malignant neoplasm was made on lung biopsy. On immunohistochemistry, the malignant cells were positive for myogenin, myoblast determination protein 1 (MyoD1), and desmin. They were negative for neuroendocrine, germ cell, epithelial, melanocytic, and lymphoid markers. Further workup showed an abdominopelvic retroperitoneal mass on abdominal computed tomography (CT) scan. The biopsy on the retroperitoneal mass showed similar morphology and immunohistochemical profile. Unfortunately, the patient's condition deteriorated rapidly in the following weeks, and he passed away.

Monophasic spindle cell myxoid synovial sarcoma of the hand: promising results with marginal resection

Synovial sarcomas are deep-seated, genetically distinct, malignant neoplasms seen in young adults, with a male preponderance. They have unusual clinical and pathological presentation and mimic many other sarcomas and carcinomas, making the diagnosis quite challenging. Although four variants are identified, occurrence in the hand is extremely rare and leads to significant morbidity. There is a high incidence of local recurrence and distant metastasis within the first 2 years. We report the case of an elderly woman with monophasic spindle cell synovial sarcoma who presented with painless swelling in her palm and underwent local excision of the neoplasm. At 2-year follow-up, she remains totally asymptomatic with normal function of the hand. We also attempt to give an overview about monophasic spindle cell synovial sarcoma with the differentials, which would help surgeons in prompt diagnosis and appropriate management.

Epithelioid Sarcoma of the External Auditory Canal: An Uncommon Tumor at an Unusual Site and a Brief Overview of the Literature

We present a case (41 years old pregnant female) with epithelioid sarcoma arising in the left external auditory canal. On immunohistochemistry, the tumor cell diffusely expressed cytokeratins and showed patchy expression of ERG and CD34. The neoplastic cells demonstrated uniform loss of INI1-expression. Epithelioid sarcoma arising in the external auditory canal is rare. Awareness that ES may rarely arise at unusual sites is of critical importance in order to apply a broad enough panel in the immunohistochemical study, so a misdiagnosis of carcinoma can be avoided.

Metaplastic carcinomas of the breast without evidence of epithelial differentiation: a diagnostic approach for management

AIMS

Although rare, malignant sarcomatoid breast tumours without evidence of epithelial differentiation comprise a diagnostic challenge with management implications. Earlier studies have generally considered these to be primary breast sarcomas; however, supporting evidence is lacking and management remains variable. This study aimed to provide an evidence-based approach to improve the consistency of diagnosis and management for such cases.

METHODS AND RESULTS

A large series (n = 140) of metaplastic breast carcinoma (MBC) diagnosed in Nottingham over 18 years was analysed. Only cases with available data on immunohistochemical expression of cytokeratins (CKs) were included. The prevalence and pattern of expression for various CKs were assessed and details of tumours negative for CKs were collected. A diagnostic approach based on our experience is provided. Forty-seven cases (34%) showed foci of conventional type invasive breast carcinoma or ductal carcinoma in situ (DCIS), while 93 cases (66%) were diagnosed as MBC based on morphology and/or CK expression. Ninety-seven cases (69%) were negative for one or more CKs, with 18 cases (13%) negative for five or more CKs. Eight cases (6%) lacked expression of all CKs tested. Further examination showed evidence of carcinomatous nature in five cases, and three were diagnosed as MBC following extensive diagnostic work-up and based on our experience.

CONCLUSION

This study suggests that MBC represents a spectrum of neoplasms, with some lacking CK expression. Sarcomatoid neoplasms of the breast lacking evidence of carcinomatous morphology and CK expression may represent an extreme end of differentiation that can be considered as carcinomas rather than sarcomas for management purposes (following extensive work-up).

Primary angiosarcoma of the oral cavity in a young adult

Angiosarcoma is a rare neoplasm, constituting only 2% of all the soft tissue tumors and most frequently involves the skin of the head and neck region in elderly males. They are extremely aggressive tumors with high rates of metastasis and poor outcomes. We report a unique case of angiosarcoma involving an unusual site – upper alveolus and maxilla in a young patient highlighting the diagnostic challenges in such a scenario. A 29 years old female presented with a non-healing wound of the oral cavity, which had progressed to the current maximum size of 6.4 cm within one month. Magnetic resonance imaging (MRI) scan revealed the involvement of maxilla up to the floor of the orbit and adjacent soft tissue. However, no distant metastasis was detected on Positron Emission Tomography (PET) scan. Biopsy of the lesion showed an irregular, highly pleomorphic, and mitotically active epithelioid soft tissue tumor conclusively diagnosed as angiosarcoma.

Diagnostic Value of Contrast-Enhanced Ultrasound for Differential Diagnosis of Malignant and Benign Soft Tissue Masses: A Meta-Analysis

This meta-analysis was aimed at investigating the value of using contrast-enhanced ultrasound (CEUS) in the differential diagnosis of benign and malignant soft tissue masses (STMs). Relevant studies published before March 24, 2020 were identified through a comprehensive search of PubMed, Ovid, Cochrane and Web of Science. According to the inclusion criteria, five studies were selected comprising 746 patients. In the differential diagnosis of benign and malignant STMs, the pooled sensitivity and specificity of CEUS were 76% (95% confidence interval [CI]: 71%-81%; heterogeneity [I²] = 74.5%) and 67% (95% CI: 62%-71%; I² = 36.5%), respectively. The diagnostic odds ratio was 7.37 (95% CI: 3.78%-14.35; I² = 66.6%). The overall area under the curve was 0.77 (standard error: 0.0392). Subgroup analysis revealed that different index tests of CEUS resulted in different diagnostic performance. Importantly, CEUS is an effective method for the differential diagnosis between benign and malignant STMs.

Amelanotic melanoma recurrence diagnosed by fine-needle aspiration cytology: A case report

Amelanotic melanoma is a variant of malignant melanoma. Amelanotic melanoma has similar morphology of a wide variety of epithelial and non-epithelial malignant tumours, variable cytomorphology of melanoma has been described on exfoliative and fine-needle aspiration cytology (FNAC). Aim of index study to describe FNAC of a rare case of recurrent amelanotic melanoma of right lateral knee swelling. Case: A 37-year-old male presented right lateral knee multi-nodular swelling last for 1 month with history of similar swelling 6 months back and operated. Histologically it was reported amelanotic malignant melanoma. FNAC revealed mordantly pleomorphic malignant cells predominantly plasmacytoid, plump shaped, prominent single to multiple nucleoli along with bi-nucleated and multi-nucleated tumour giant cells were also noted. Histology and immunohistochemistry (IHC) slides were reviewed and confirm the diagnosis. Concluded amelanotic melanoma has highly varied cytomorphology with multiple differential diagnosis and IHC markers are of great value for final diagnosis of it.

Testicular leiomyoma and spermatogenic failure syndrome in a seabass from broodstock

Testicular leiomyomas and gonadal dysfunctions are not commonly reported in teleost and particularly in broodstock fish. In the present work, a testicular leiomyoma related to an unusual case of spermatogenic failure syndrome, in a broodstock seabass coming from an Italian aquaculture farm, is reported. At gross pathology, the circumscribed neoplasia showed several white nodular masses, originating from the gonad, deforming the anatomo-physiological shape. From light microscopy, the presence of neoplastic tissue islands with spindle cells with a whirling pattern and the low presence of connective tissue were evident and originated from smooth muscle cells. Seminiferous tubules showed severe azoospermia with the absence of sperm cells even closer to the neoplastic area. Immunohistochemical analysis was positive for alpha-SMA, desmin and vimentin but negative for S-100, confirming a diagnosis of leiomyoma. This is the first report of spermatogenic failure syndrome associated with a testicular leiomyoma in fish from broodstock. More efforts should be made in studying broodstock fish pathologies related to fish maintenance and hormonal treatments that could economically affect aquaculture production.

Sarcoma treatment in the era of molecular medicine

Sarcomas are heterogeneous and clinically challenging soft tissue and bone cancers. Although constituting only 1% of all human malignancies, sarcomas represent the second most common type of solid tumors in children and adolescents and comprise an important group of secondary malignancies. More than 100 histological subtypes have been characterized to date, and many more are being discovered due to molecular profiling. Owing to their mostly aggressive biological behavior, relative rarity, and occurrence at virtually every anatomical site, many sarcoma subtypes are in particular difficult-to-treat categories. Current multimodal treatment concepts combine surgery, polychemotherapy (with/without local hyperthermia), irradiation, immunotherapy, and/or targeted therapeutics. Recent scientific advancements have enabled a more precise molecular characterization of sarcoma subtypes and revealed novel therapeutic targets and prognostic/predictive biomarkers. This review aims at providing a comprehensive overview of the latest advances in the molecular biology of sarcomas and their effects on clinical oncology; it is meant for a broad readership ranging from novices to experts in the field of sarcoma.

Diagnostic Utility of a Custom 34-Gene Anchored Multiplex PCR-Based Next-Generation Sequencing Fusion Panel for the Diagnosis of Bone and Soft Tissue Neoplasms With Identification of Novel USP6 Fusion Partners in Aneurysmal Bone Cysts

CONTEXT.—

Bone and soft tissue tumors are heterogeneous, diagnostically challenging, and often defined by gene fusions.

OBJECTIVE.—

To present our experience using a custom 34-gene targeted sequencing fusion panel.

DESIGN.—

Total nucleic acid extracted from formalin-fixed, paraffin-embedded (FFPE) tumor specimens was subjected to open-ended, nested anchored multiplex polymerase chain reaction and enrichment of 34 gene targets, thus enabling detection of known and novel fusion partners.

RESULTS.—

During a 12-month period, 147 patients were tested as part of routine clinical care. Tumor percentage ranged from 10% to 100% and turnaround time ranged from 3 to 15 (median, 7.9) days. The most common diagnostic groups were small round blue cell tumors, tumors of uncertain differentiation, fibroblastic/myofibroblastic tumors, and adipocytic tumors. In-frame fusion transcripts were identified in 64 of 142 cases sequenced (45%): in 62 cases, the detection of a disease-defining fusion confirmed the morphologic impression; in 2 cases, a germline TFG-GPR128 polymorphic fusion variant was detected. Several genes in the panel partnered with multiple fusion partners specific for different diagnoses, for example, EWSR1, NR4A3, FUS, NCOA2, and TFE3. Interesting examples are presented to highlight how fusion detection or lack thereof was instrumental in establishing accurate diagnoses. Novel fusion partners were detected for 2 cases of solid aneurysmal bone cysts (PTBP1-USP6, SLC38A2-USP6).

CONCLUSIONS.—

Multiplex detection of fusions in total nucleic acid purified from FFPE specimens facilitates diagnosis of bone and soft tissue tumors. This technology is particularly useful for morphologically challenging entities and in the absence of prior knowledge of fusion partners, and has the potential to discover novel fusion partners.

Primary superficial synovial sarcoma: clinical and histopathological characteristics in eight cases with molecular confirmation

BACKGROUND AND AIMS

Synovial sarcoma (SS) is a spindled cell sarcoma demonstrating varying degrees of epithelial differentiation and characterized by a pathognomonic t(X;18) translocation. SS most frequently involves deep soft tissue of the extremities in young adults. Superficial SS involving dermis and/or subcutaneous tissue is exceedingly rare.

METHODS AND RESULTS

We identified eight cases of primary superficial synovial sarcomas across three tertiary institutions. All cases were confined to the dermis/subcutis based on imaging or gross and microscopic examination. The average patient age was 36 years (range 14-50). The average tumor size was 2.4 cm (range 0.9-3.9 cm) and lesions showed classic monophasic (n = 4) or biphasic (n = 4) morphology. All tumors expressed keratin AE1/AE3 and/or epithelial membrane antigen (EMA), but were negative for CD34. The diagnosis for each case was confirmed by molecular detection of t(X;18). Six of the eight cases were treated with curative excision while the other two received additional radiotherapy. Follow-up was available for six patients (mean 68 months, range 2-108 months) and no patient experienced recurrence or metastatic disease.

CONCLUSIONS

We present the largest series to date of primary superficial SS with molecular confirmation for all cases. SS should be considered when evaluating a cutaneous monomorphic spindle cell neoplasm.

Intravascular schwannoma: A review of a rare diagnosis

While schwannoma is one of the most common types of benign peripheral nerve tumors in adults, a very unique and specific variant of schwannoma, the intravascular variant, is exceedingly rare. There have only been three previously published cases of intravascular schwannomas. Here we describe a fourth case of an intravascular schwannoma in a 47-year-old man with an enlarging subcutaneous nodule on his posterior calf. This is the second case of an intravascular schwannoma contained within a vein. Also included is an overview of intravascular schwannomas, including a description and discussion of the histopathological diagnosis, differential diagnoses, and schwannoma variants.

Abdominal perivascular epithelioid cell tumor (PEComa) without visible fat: a clinicopathologic and radiological analysis of 16 cases

OBJECTIVE

To retrospectively review the clinicopathological features and computed tomography (CT) and magnetic resonance imaging (MRI) findings of abdominal perivascular epithelioid cell tumor without visible fat (PEComa_wvf).

MATERIALS AND METHODS

Sixteen patients with surgically and pathologically confirmed perivascular epithelioid cell tumor without visible fat were enrolled. Their clinicopathological data and imaging findings were retrospectively reviewed. The CT and MRI features, including location, size, shape, margin, density, calcification, cystic necrosis and enhancement pattern, were analyzed.

RESULTS

There were 4 males and 12 females (median age, 46 years; range, 21-65 years) in this study. All 16 patients were diagnostic asymptomatic unenhanced CT or MRI and revealed a well-defined (n = 13), oval (n = 10), mass with heterogeneous (n = 6) or homogeneous density/signal intensity (n = 7), calcification and hemorrhage was no found in any cases. On enhanced CT/MRI, markedly enhancement patterns (n = 14) were observed. The "peripheral enhancement" sign was observed in 13 cases. One in 16 cases recurrence was discovered during the follow-up period.

CONCLUSIONS

Dynamic CT, MRI and pathology of PEComa_wvf had some characteristics of non-aggressive pattern of performance, and MRI would provide beneficial detection of microscopic fat. Enhanced imaging showed PEComa_wvf is characterized by a "peripheral enhancement" with a marked enhancement pattern. Knowing these characteristics could contribute to improving the understanding abdominal PEComa_wvf and related palliative care.

Classification and Clinicopathologic Study of Orofacial Mesenchymal Tumors: A Retrospective Study

Aim:

To determine the prevalence of orofacial mesenchymal neoplasms and classify them using the WHO criteria while appraising its applicability.

Materials and Methods:

This was a retrospective study involving a total sample of 192 entries diagnosed as mesenchymal tumors for the period 1990-2018 at the Oral Pathology Department, University College Hospital, Ibadan. The histopathology records were examined and clinicopathological data were obtained. Hematoxylin and Eosin slides of the cases were assessed to confirm the diagnosis. Tumors were classified using the WHO 2013 classification. Data were analyzed and presented using descriptive statistics.

Results:

Orofacial mesenchymal tumors constituted 7.9% of 2402 biopsies. There were 26 diagnoses in 161 tumors of the WHO classification. Male-to-female ratio was 1.1:1. Peak age group was in the third decade. Soft tissue tumors were 61.5%, while bone tumors were 38.5%. Benign tumors constituted 49.5%, while sarcomas and intermediate tumors were 45.8% and 4.7%, respectively. The mandibular region (29.7%) was the most commonly affected site. Adipocytic and osteogenic tumors were the most prevalent tumors in the soft tissue and osteoarticular series, respectively, representing 19.8% and 32.3% of all cases, while orofacial sarcomas constituted 3.6% of all lesions seen.

Conclusion:

The findings in this study are in line with those of previous studies. However, the WHO classification may not be suited for the orofacial region. Crafting of a classification system for mesenchymal tumors of the orofacial region would thus be necessary.

Primary pancreatic Ewing sarcoma: a cytomorphologic and histopathologic study of 13 cases

INTRODUCTION

Ewing sarcoma (ES) is a small, round cell sarcoma that rarely occurs in solid organs, including the pancreas. A diagnostic overlap exists with other primary pancreatic neoplasms, especially for specimens from small biopsies and fine needle aspiration (FNA). To improve the diagnosis of this rare pancreatic tumor, we have reported a series of 13 cases of primary pancreatic ES and reviewed the cytopathologic, surgical pathology, clinical, and radiologic features of these neoplasms.

MATERIALS AND METHODS

We performed a retrospective case review of 13 patients with a diagnosis of pancreatic ES from 2 tertiary academic medical centers. A combination of cytology and histopathologic slides were reviewed, and the patient demographics, clinical information, somatic genetics, and radiologic findings were obtained from the electronic medical records.

RESULTS

Five FNA specimens from 5 patients and 8 surgical biopsy or resection specimens were identified and reviewed. The patients included 9 males and 4 females, with a median age of 27 years (range, 15-78 years). The cytology smears were highly cellular and showed a combination of complex tissue fragments and singly dispersed small round blue cells. The final diagnosis was ES for all 5 FNA specimens in accordance with the characteristic cytomorphology, diffuse and/or strong membranous immunolabeling for CD99, membranous β-catenin, and molecular confirmation of EWSR1 using fluorescence in situ hybridization or reverse transcriptase polymerase chain reaction.

CONCLUSIONS

The cytologic diagnosis of ES is challenging, especially in unusual locations such as the pancreas. However, the correct cytologic diagnosis is important because these patients will require neoadjuvant therapy before surgery. Confirmatory molecular studies should be required to render the diagnosis of pancreatic ES.

Survey of pathology reports with no definitive diagnosis in oral lesions: the necessary skills for the clinicians

Purpose

Biopsy plays a crucial role in definitive diagnosis of lesions and consequently, appropriate treatment of them. Clinicians should correctly do the biopsy in accordance to the existing principles and guidelines to prevent adverse effects on the pathologist's diagnosis. This study aimed to determine the frequency and reasons for not providing definitive histopathological diagnosis of the biopsy samples belong to the laboratory of the Department of Oral and Maxillofacial Pathology, Faculty of Dentistry, Hamadan University of Medical Sciences.

Methods

Archival reports belong to 2006–2016 period of the related laboratory were studied to determine the reports with no definitive histopathological diagnosis.

Results

Out of 1018 archived reports; 90 reports (8.84%) had no definitive diagnosis. The most common reasons found were incompatibility between the clinical/radiographical diagnosis and histopathological findings for 42 cases (46.66%), absence of adequate information about the clinical/radiographical findings for 17 cases (18.88%) and inappropriate quality of samples for 13 cases (14.44%), respectively.

Conclusion

The reasons for not providing definitive histopathological diagnosis of the biopsy samples in present study indicated that preparation, assessment and diagnosis of microscopic slide by pathologists do not separate from the clinician performance.

Mesenchymal neoplasms: Is it time for cytology? New perspectives for the pre-operative diagnosis of soft tissue tumors in the molecular era

Soft tissue tumors comprise a great variety of common and rare entities with overlapping features. Their diagnosis is based on the evaluation of several histological parameters which are difficult to assess on small incisional biopsies. Useful diagnostic markers in the field of soft tissue tumors include: 1) molecular biomarkers detecting pathogenetically relevant, distinctive alterations; 2) immunohistochemical surrogate biomarkers of pathogenetically relevant, distinctive molecular alterations; 3) highly specific immunohistochemical biomarkers indicating tumor differentiation. Their introduction in clinical practice has revolutionized the pre-operative diagnosis of soft tissue tumors. Cytology has long been considered inadequate as a first-line approach in this setting. However, since the implementation of new immunohistochemical and molecular tests with high diagnostic specificity, fine needle aspiration cytology (FNAC) is starting to gain acceptance for the pre-operative assessment of soft tissue tumors. FNAC represents a versatile, poorly expensive and well-tolerated diagnostic strategy with relevant advantages over histological biopsies. Moreover, evidences suggest that, in expert hands, FNAC can also aim at a definite diagnosis, especially if a cell block is prepared, allowing the application of multiple ancillary techniques.

Comprehensive Review of Abdominopelvic Mesenchymal Tumors with Radiologic Pathologic Correlation and Update on Current Treatment Guidelines - Part 1

Soft-tissue sarcomas are a diverse group of rare mesenchymal malignancies accounting for only 1% of all solid adult malignancies. These have been categorized in 12 broad groups by the World Health Organization (WHO) with their recent update in 2013. Majority of them lack specific imaging features serving as imaging conundrums for a radiologist. These are often large masses at presentation as they are asymptomatic or cause vague clinical symptoms. These tumors are challenging for surgeons as well as they find it difficult to achieve complete resection because of complex intra-abdominal anatomy and their close relationship with critical structures. Often, a multidisciplinary approach is required to decide on the most appropriate management for these complex cases so as to provide optimal patient care. Knowledge of the WHO classification, pathologic features and available treatment options will help the radiologist make a meaningful contribution in multidisciplinary discussions of such cases and overall patient care. Liposarcoma (well-differentiated and dedifferentiated liposarcomas), leiomyosarcoma, and gastrointestinal stromal tumor are the 3 most common primary intra-abdominal sarcomas. In part 1 of this article, general features of soft tissue sarcomas and some of the common tumors from WHO category 1-4 found in abdomen and pelvis are discussed. Part 2 will focus on common tumors from remainder of the WHO categories.

Abdominal wall schwannoma: a case report

Schwannomas or neurilemmomas are benign and slow-growing tumors that arise exclusively from Schwann cells in peripheral nerve sheaths. These neoplasms theoretically can occur anywhere in the body, but they most frequently affect extremities, as well as head and neck region. However, their presentation in the abdominal wall is extremely rare and only few cases have been reported in the literature. Subcutaneous lesions may be asymptomatic and only incidentally discovered upon physical examination or imaging. However, occasionally they induce mass effects on surrounding large nerves. We present the case of a 34-year-old man with abdominal wall pain localized in the right iliac fossa and palpable subcutaneous mass. Ultrasound and CT scan revealed a solid well-defined mass of the abdominal wall. Following surgical excision under general anesthesia, histological examination was consistent with the diagnosis of benign schwannoma.

Ewing Sarcoma With Emphasis on Extra-skeletal Ewing Sarcoma: A Decade's Experience From a Single Centre in India

INTRODUCTION

The diagnosis of Ewing sarcoma family of tumours (ESFT) is challenging, especially in adults and in extra-skeletal or visceral location. Several morphologic mimics with varied treatment options and prognosis confer diagnostic dilemmas. Application of ancillary diagnostic modalities in surgical pathology in clinical routine has enabled accurate diagnosis of ESFT in bone, soft tissues, and viscera.

AIM

The study aims to assess the clinicopathological features including molecular test results of ESFT with emphasis on sex, age, and location, especially extra-skeletal soft tissue and visceral location.

MATERIAL AND METHODS

Data of clinicopathological, molecular tests (wherever performed), diagnosis rendered in 302 ESFT over a decade from our centre were reviewed. Statistical comparison of skeletal and extra-skeletal tumours with reference to age and sex was done using SPSS package. The P value of <.05 was considered significant.

RESULTS

The cohort included 302 ESFTs with 49% skeletal and 51% extra-skeletal tumours. Thigh was most common site among skeletal tumours; chest wall, paraspinal location, and retroperitoneum among soft tissues (39.4%); and kidney, ovary, and cervix among visceral tumours (11.3%). Fluorescence in situ hybridisation for EWSR1 gene rearrangement was positive in 54 patients and reverse-transcriptase polymerase chain reaction in 19 patients. Predominance of male sex, younger age and location in extremities among skeletal tumours and lack of gender predilection, higher age and axial location in extra-skeletal tumours were noted, which were statistically significant. Molecular tests were performed more frequently in extra-skeletal tumours, especially in visceral tumours to establish the diagnosis.

CONCLUSIONS

The study showed statistically significant differences in the age, sex, and location between skeletal and extra-skeletal ESFT. The increased percentage of extra-skeletal tumours especially in viscera was attributed to the increased awareness and availability of ancillary techniques.

Soft tissue tumor diagnosis: A three prong approach utilizing pattern analysis, immunocytochemistry, and molecular diagnostics

Tissue diagnosis of a soft tissue neoplasm is of paramount importance for the development of an appropriate treatment plan. Biopsy technique including approach and biopsy method is important to the success of diagnosis and subsequent treatment. Histologic and cytologic diagnoses are difficult and complicated by the large number of soft tissue lesions described, distinctly different biopotential for morphologically similar lesions, often small biopsy specimen size, and the generally limited experience many pathologists have in the diagnosis of soft tissue neoplasms. While utilized less frequently than core-needle biopsies, fine-needle aspiration is a valuable initial approach for the classification of soft tissue neoplasms. The combination of pattern based morphologic analysis, immunohistochemistry, and molecular diagnostics represents a utilitarian and generally successful approach for the diagnosis of soft tissue lesions.

Size-Optimized Ultrasmall Porous Silica Nanoparticles Depict Vasculature-Based Differential Targeting in Triple Negative Breast Cancer

Rapid sequestration and prolonged retention of intravenously injected nanoparticles by the liver and spleen (reticuloendothelial system (RES)) presents a major barrier to effective delivery to the target site and hampers clinical translation of nanomedicine. Inspired by biological macromolecular drugs, synthesis of ultrasmall (diameter ≈12-15 nm) porous silica nanoparticles (UPSNs), capable of prolonged plasma half-life, attenuated RES sequestration, and accelerated hepatobiliary clearance, is reported. The study further investigates the effect of tumor vascularization on uptake and retention of UPSNs in two mouse models of triple negative breast cancer with distinctly different microenvironments. A semimechanistic mathematical model is developed to gain mechanistic insights into the interactions between the UPSNs and the biological entities of interest, specifically the RES. Despite similar systemic pharmacokinetic profiles, UPSNs demonstrate strikingly different tumor responses in the two models. Histopathology confirms the differences in vasculature and stromal status of the two models, and corresponding differences in the microscopic distribution of UPSNs within the tumors. The studies demonstrate the successful application of multidisciplinary and complementary approaches, based on laboratory experimentation and mathematical modeling, to concurrently design optimized nanomaterials, and investigate their complex biological interactions, in order to drive innovation and translation.

Pseudomyogenic Hemangioendothelioma (Epithelioid Sarcoma-Like Hemangioendothelioma)

Pseudomyogenic hemangioendothelioma (PMH) is a rare vascular tumor that presents more frequently in young adults and has a male predominance. It is usually located in the superficial or deep soft tissues of the extremities, but concurrent bone involvement can be present. In approximately two-thirds of patients this disease is multifocal, often involving multiple tissue planes. It is a relapsing lesion with low metastatic potential. Given its clinical and morphologic characteristics (multifocality, epithelioid morphology, absence of clearly evident vascular differentiation on hematoxylin-eosin slides), PMH can be easily misinterpreted as other lesions, often with radically different treatment and prognosis. For this reason, we think it is important to recognize this entity, which has some unique features. Here, we will briefly describe the clinical and pathologic features of PMH, detailing its more relevant differential diagnoses.

A Rare Case of a Primary Unilateral Low-Grade Paratesticular Leiomyosarcoma in a 2 Years Old Dog

A 2 years old dog was brought to the clinic with complains of testicular enlargement. The tissue was diffusely affected as confirmed by ultrasonographic examination, being the right testicle atrophied and the right epididymis enlarged, with loss of echotexture and presence of several anechogenic areas. The situation required the excision of the referred testicle and epididymis. Final diagnose made by histopathological analysis was primary unilateral low-grade paratesticular leiomyosarcoma. Scarce bibliography is found on this matter, with several cases reported on human, and none in dog. This case report is therefore an important milestone on the area of small animal oncology directly related to the reproductive tissue.

An unusual case of recurrent huge primary mediastinal dedifferentiated liposarcoma

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This is an extremely rare case and quite challenging both to diagnose and to treat.

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Immunostaining is sometimes needed to confirm the diagnosis.

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Contrary to most similar reported case, the tumor recurred after surgery.

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Although rarely needed, chemotherapy may successfully prevent tumor progression.

Introduction

Primary mediastinal dedifferentiated liposarcoma is an extremely rare malignant mesenchymal neoplasm composed of lipogenic tissue. It can be huge enough to compress heart and surrounding organs leading to clinical symptoms.

Presentation of case

We present a case of huge primary mediastinal dedifferentiated liposarcoma in a 54-year-old man, confirmed by immunohistochemistry staining, who received surgical removal. However, six months later, the tumor recurred, and the patient underwent chemotherapy for 6 cycles resulting in stable disease. Six months after the last visit, the tumor showed no sign of recurrence anymore.

Discussion

Among the various subtypes, the dedifferentiated mediastinal liposarcoma is the least found type of liposarcoma and often leads to misdiagnosis. Challenges occurred not only in diagnosis but also in treatment since it frequently grows back and chemotherapy may be needed after surgery.

Conclusion

This is a highly rare case of huge mediastinal liposarcoma that recurred after surgery and gave a satisfying outcome after chemotherapy.

Malignant progression of a peripheral nerve sheath tumor in the setting of rhabdoid tumor predisposition syndrome

Malignant progression of a benign or low-grade tumor in individuals with germline alteration of SMARCB1 gene is not well characterized. In a family in which two carrier children had germline SMARCB1 mutations and atypical teratoid rhabdoid tumor, we report malignant progression of a nerve sheath tumor over a 7-year period in an affected adult family member. Prompt identification of the germline SMARCB1 alteration and the resultant rhabdoid tumor predisposition syndrome can help guide genetic counseling and surveillance in affected family members.