Fine-needle aspiration in desmoplastic small round cell tumor: a report of 10 new tumors in 8 patients with clinicopathological and molecular correlations with review of the literature

Soft Tissue Fine-Needle Aspiration: Current and Future Impact on Patient Care

Soft tissue neoplasms pose many diagnostic challenges on fine-needle aspiration (FNA), owing largely to their rarity, large number of entities, and histologic diversity. Advances in ancillary testing now allow detection of the characteristic immunophenotypes and molecular alterations for many neoplasms and include reliable surrogate immunohistochemical markers for underlying molecular events that are highly efficient in small biopsies. A morphology-based framework is recommended to guide appropriate differentials and judicious selection of ancillary tests for small biopsies. The accurate diagnosis of soft tissue tumors is crucial for patient management and prognostication, with many potential implications in this era of precision medicine.

Highlighting the Diversity of Desmoplastic Small Round Cell Tumor: A Case Series

Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor that occurs mainly in the retroperitoneum of children and young adults. In its prototypical form, DSCRT displays characteristic morphology with nested primitive small round cells in a desmoplastic stroma and a distinctive immunophenotype with polyphenotypic differentiation. However, DSCRT can also exhibit a broader clinical, histologic and immunohistochemical spectrum and, therefore, cause diagnostic difficulties. Given that DSCRT is an aggressive and nearly universally fatal disease, making the correct diagnosis is critically important. Herein, we report three patients with DSRCT and unusual clinical, morphologic or immunohistochemical characteristics, in order to highlight its remarkable diversity and increase awareness of this unusual, distinctive neoplasm.

The Small Round Cell Sarcomas Complexities and Desmoplastic Presentation

Background

Small round cell sarcomas (SRCSs) account for most solid malignancies in the pediatric age group and are a part of group of malignant tumors characterized by heterogenous clinical presentation and overlapping microscopic features of small, round, primitive cells. In addition to the recently established certain genetically defined subset of undifferentiated round cell sarcomas of soft tissue and bone, this group of sarcomas include desmoplastic small round cell tumor, poorly differentiated synovial sarcoma, alveolar rhabdomyosarcoma, mesenchymal chondrosarcoma, and small cell osteosarcoma. Although, those entities share clinical and cytomorphologic features and cannot be unequivocally classified based on clinical presentation and morphology alone. Most of SRCSs characterizes of particular patterns of protein expression or genetic changes and ancillary tests remain necessary to confirm or rule out a specific diagnosis. Subtle but occasionally distinctive cytologic features narrows the number of differential diagnoses and helps to select appropriate ancillary tests necessary for the final diagnosis. Thus, when adequate fine needle aspiration (FNA) biopsy specimen is combined with ancillary tests, a specific histologic diagnosis can be made in almost all cases. However, due to complex cytologic features of SRCS as well as various quality and diversity of FNA smears, there are cases in that cytologic features which do not entirely match the known diagnostic criteria.

Summary

The aim of this review was to summarize cytomorphologic criteria and to present rare and divergent cytological features of SRCSs. Careful assessment of clinical presentation, cytological features, immunohistochemical patterns, and molecular alternations is necessary for an accurate diagnosis. Knowing of rare and divergent microscopic findings that does not fit with the known cytological criteria will help to avoid misdiagnosis.

Key Messages

The role of FNA biopsies diagnosing soft tissue and bone tumors has been increasing because of the ability of ancillary tests to assist in the diagnosis of specific tumors. SRCSs may be diagnosed accurately in cytology specimens. Access to clinical and radiographic presentation, utility of ancillary tests, understanding complexity of cytological features, and awareness of the rare cytologic findings that differ from that of the established diagnostic criteria are essential to make correct diagnosis.

Cytology of Undifferentiated Round-Cell Sarcomas of Bone and Soft Tissue: Ewing Sarcoma or Not Ewing Sarcoma , That Is the Question

BACKGROUND

Undifferentiated round-cell sarcomas (URCSs) of soft tissue and bone are a group of clinically heterogeneous tumors. Diagnosis of these malignancies is based mainly on recurrent genetic alterations. The most common and the best known representative of this group is Ewing sarcoma (ES) which is characterized by gene fusions including EWSR1 or FUS and ETS transcription factors family. Other newly described entities are CIC-rearranged sarcoma, sarcoma with BCOR genetic alterations, and round-cell sarcoma with EWSR1-non-ETS fusions. All these novel tumors are known as Ewing-like sarcomas.

SUMMARY

It is believed that morphologic features of ES and Ewing-like sarcomas vary only slightly or even that cytomorphology is not relevant. But differences are usually obvious, and some cytologic findings, such as spindle cells, connective tissue fragments, or myxoid stroma, are typical for Ewing-like sarcomas but not for ES. Each of these entities is also characterized by different immunoprofiles. The aim of this review was to summarize cytomorphologic and immunohistochemical features of URCS and compare them with other small round-cell tumors. Key Messages: Cytology can be successfully used in URCS diagnosis as a complementary tool for core-needle biopsy or even alone in selected cases, especially in recurrent and metastatic tumors. Knowing the morphologic and immunohistochemical differences between URCS is essential to provide appropriate ancillary studies and make a definitive diagnosis.

Desmoplastic Small Round Cell Tumors: A review with focus on clinical management and therapeutic options

Desmoplastic Small Round Cell Tumors (DSRCTs) are an entity of rare, aggressive soft tissue sarcomas described by Gerald and Rosai in 1989. It predominantly affects male adolescents and young adults, with a peak incidence between an age of 20 and 30 years. Typically, DSRCT demonstrate as multiple small tumor nodules within the abdominal cave, retroperitoneum and pelvis. In more than 50% of the cases, the neoplasm presents metastatic at the timepoint of diagnosis. Histologically, DSRCTs have a characteristic morphology with sharply demarcated islands of uniform small round cells in abundant desmoplastic stroma organized in loose extracellular matrix. Immunohistochemistry reveals a polyphenotypic differentiation with co-expression of epithelial, myogenic, mesenchymal and neural markers. The morphology is highly variable and can hinder diagnosis. The most consistent molecular characteristic of DSRCT is the reciprocal t(11;22)(p13q12) translocation. This mutation leads to a formation of the EWSR1-WT1 fusion oncogene, which encodes for a chimeric protein with transcriptional regulatory activity and is regarded as driving source of the disease. To date, there is no standardized concept for clinical management, staging and treatment. Patients receive an aggressive multimodal therapeutic approach consisting of chemotherapy, radical surgical procedures, hyperthermic, intraperitoneal chemotherapy (HIPEC) and radiation. New targeted therapies are used in experimental settings as salvage therapy. So far, none of these therapies showed significant long-term success. This review gives an overview of diagnostic difficulties and pitfalls, discusses therapeutic strategies and highlights options for clinical management.

Desmoplastic Small Round Cell Tumor of the Kidney: Report of a Case, Literature Review, and Comprehensive Discussion of the Distinctive Morphologic, Immunohistochemical, and Molecular Features in the Differential Diagnosis of Small Round Cell Tumors Affecting the Kidney

Desmoplastic small round cell tumor (DSRCT) is a rare, highly aggressive neoplasm typically presenting with widespread involvement of the abdominopelvic peritoneum of adolescent males, usually without organ-based primary. Although it is believed to originate from the serous (mainly peritoneal) membranes, intracranial, sinonasal, intraosseous, and other soft tissue sites are also documented. A chromosomal translocation t(11:22)(p13;q12) signature that fuses EWSR1 and WT1 genes results in the production of a chimeric protein with transcriptional regulatory activity that drives oncogenesis. Integration of clinical, morphologic, immunohistochemical, and genetic data is necessary to arrive at the correct diagnosis, especially when the tumor arises in an atypical site. A 15-year-old male presented with hematuria and was found to have a large renal tumor associated with adrenal, liver, lung, and bone metastases. Histopathologic and immunophenotypic features were distinctive for DSRCT. This diagnosis was confirmed by means of fluorescence in situ hybridization and cytogenetic analysis, which documented the pathognomonic t(11;22) translocation, and by reverse transcription polymerase chain reaction on snap-frozen tissue, which revealed the EWSR1/WT1-specific chimeric transcript. Despite high-dose chemotherapy and radiation therapy targeted to a single T11 vertebral metastasis, the disease progressed, and the patient died 4 years after the diagnosis. A search of electronic databases for DSRCT yielded 16 cases of well-documented renal primaries out of around 1570 cases from all sites gathered from the global literature. Desmoplastic small round blue cell tumor and other primary renal tumors considered in the differential diagnosis with DSRCT are discussed.

A comprehensive diagnosis of a desmoplastic small round cell tumor of unusual location based on fine-needle aspiration cytology: Report of a case arising in the parotid gland and review of the literature

Desmoplastic small round cell tumor (DSRCT) is rare and a highly aggressive neoplasm that typically involves the soft tissues of the abdomen or pelvis in children or young adults, showing a male predilection. Although it can occurs over a wide age range, the peak incidence is in the third decade of life. DSRCT usually shows widespread abdominal serosal involvement, and overall patient survival is poor. On the other hand, extra-abdominal DSRCT is very rare. DSRCT in major salivary glands has been reported, but it is extremely rare. In the majority of reported series diagnosis is made by the histological analysis of FFPE tissues together with immunohistochemistry (IHC) and molecular analysis, particularly the demonstration of chromosomal translocation involving EWSR1. Very few cases have been diagnosed so far by Fine Needle Aspiration (FNA) cytology. Moreover ancillary studies have been performed in all reported cases in FFPE samples. There is still controversy and lack of consensus regarding the suitability of cytological samples especially smears for immunocytochemical (ICC) and fluorescence in situ hybridization (FISH), what makes its standardization difficult. We report a case of a primary DSRCT of parotid gland in a 17-year-old male diagnosed by FNA cytology. The cytomorphological diagnosis was coupled with ICC and FISH analysis performed on stained smears. We emphasize the feasibility and reliability of cytological smears for the application of immunocytochemical and molecular techniques.

Mesenchymal neoplasms of the tubular gut and adjacent structures: experience with EUS-guided fine-needle aspiration cytopathology

INTRODUCTION

Unlike epithelial malignancies, mesenchymal neoplasms arising within the tubular gut are less often encountered in endoscopic ultrasound-guided (EUS) fine-needle aspiration biopsies (FNABs). Nonetheless, preoperative diagnosis of such neoplasms has important therapeutic and prognostic value. We report our experience with this category of neoplasms from the past decade.

MATERIALS AND METHODS

We performed a 10-year retrospective search at our respective institutions to identify EUS-guided FNAB cases of mesenchymal neoplasms arising from the tubular gut wall and closely adjacent structures. Cytopathologic diagnoses were compared to corresponding surgical pathology (SP) when available. Cases with either no confirmatory cell block (CB) immunohistochemical (IHC) staining, or no SP were excluded.

RESULTS

Two-hundred eighty-two cases (M:F = 1:1; age range: 25-94 years, mean age = 60 years) of EUS-guided FNAB from the tubular gut met our criteria. Onsite adequacy was performed on nearly all cases. Case numbers: 209 gastrointestinal stromal tumors (GIST), 58 smooth muscle neoplasms, and 15 miscellaneous neoplasms. Of these, 188 (67%) had SP follow-up. We found that 258 (91%) aspirates had a correct specific diagnosis, 3 (1%) were nondiagnostic, 18 (6%) had indeterminate diagnoses, and 3 (1%) had incorrect diagnoses (2 leiomyosarcomas mistaken as leiomyoma, and 1 fibrosclerotic lesion mistaken as inflammatory pseudotumor). Of 94 cases with no SP, all had a specific cytologic diagnosis based on confirmatory IHC staining from the CB including 61 GISTs, 29 smooth muscle neoplasms, and 4 miscellaneous tumors.

CONCLUSION

This study endorses the clinical utility of EUS-guided FNAB in the diagnosis of tubular gut mesenchymal neoplasms. A definitive and accurate diagnosis is possible in over 90% of cases, chiefly when cytomorphology is coupled with optimal cellularity and IHC from a concurrent CB. EUS-guided FNAB diagnosis of mesenchymal tubular gut neoplasms may play an important role in determining neoadjuvant therapy as targeted therapy evolves.

Fine needle aspiration cytology of paediatric soft tissue tumours highlighting challenges in diagnosis of benign lesions and unusual malignant tumours

INTRODUCTION

The type of soft tissue lesions seen in children differs from that seen in adults. The role of fine needle aspiration (FNA) cytology in their diagnosis is not well documented.

AIM

To study the cytopathological spectrum of paediatric soft tissue tumours to highlight uncommon benign and malignant lesions and the challenges in their diagnosis.

METHODS

A 3-year retrospective audit of all paediatric soft tissue FNA cytology cases from 2015 to 2017 was performed. Smears were reviewed along with cell block immunocytochemistry and follow-up histopathology of resected specimens wherever available.

RESULTS

A total of 127 cases were reviewed, which included 72 benign and 55 malignant soft tissue tumours. Uncommon lesions described herein are myxoid fibrohistiocytic tumour, myxoma, lipoblastoma, Bednar tumour, malignant extra-renal rhabdoid tumour and desmoplastic small round cell tumour. Histopathology confirmation was available in 25 cases, out of which 16 cases were completely concordant. In eight cases, all benign diagnoses, histopathology provided more accurate subtyping than FNA. These included cases of lipoblastoma, myxoma and spindle cell haemangioma.

CONCLUSION

FNA cytology of paediatric soft tissue tumours is accurate in classifying lesions as benign or malignant which helps in treatment planning. Immunocytochemistry performed on cell blocks is useful for subtyping malignant lesions.

Fine-Needle Aspiration Features of BCOR-CCNB3 Sarcoma

OBJECTIVES

BCOR-CCNB3 sarcoma (BCS) is an undifferentiated tumor that has some clinical and morphologic similarity to classic Ewing sarcoma, but it is characterized by a distinct BCOR-CCNB3 gene fusion. There are no reports describing its cytomorphologic findings.

METHODS

We describe cytologic findings of five molecularly proven BCS cases (four males and one female, aged 8.5-22 years).

RESULTS

Smears showed mainly round cells, but some spindle cells and rhabdoid-like cells were also observed. Dispersed cells dominated in smears, but also distinct pseudopapillary structures with vascular cores were noted in four cases. Scant connective tissue fragments were found in four cases. There was no rosette formation in any case.

CONCLUSIONS

BCS should be differentiated from other round cell tumors. Some cytologic features, especially rhabdoid-like cells, connective tissue fragments, and pseudopapillary formations, combined with immunohistochemical and molecular studies, may be helpful in making the appropriate diagnosis.

Applications of Ancillary Testing in the Cytologic Diagnosis of Soft Tissue Neoplasms

Soft tissue neoplasms are diagnostically challenging, although many advances in ancillary testing now enable accurate classification of fine-needle aspiration biopsies by detection of characteristic immunophenotypes (including protein correlates of molecular alterations) and molecular features. Although there are many useful diagnostic immunohistochemical markers and molecular assays, their diagnostic utility relies on correlation with clinical and morphologic features, judicious application, and appropriate interpretation because no single test is perfectly sensitive or specific. This review discusses applications of ancillary testing for commonly encountered soft tissue neoplasms in cytopathologic practice in the context of a pattern-based approach.

Desmoplastic Small Round Blue Cell Tumor: A Review of Treatment and Potential Therapeutic Genomic Alterations

Desmoplastic small round blue cell tumors (DSRCTs) originate from a cell with multilineage potential. A molecular hallmark of DSRCT is the EWS-WT1 reciprocal translocation. Ewing sarcoma and DSRCT are treated similarly due to similar oncogene activation pathways, and DSRCT has been represented in very limited numbers in sarcoma studies. Despite aggressive therapy, median survival ranges from 17 to 25 months, and 5-year survival rates remain around 15%, with higher survival reported among those undergoing removal of at least 90% of tumor in the absence of extraperitoneal metastasis. Almost 100% of these tumors contain t(11;22) (p13;q12) translocation, and it is likely that EWS-WT1 functions as a transcription factor possibly through WT1 targets. While there is no standard protocol for this aggressive disease, treatment usually includes the neoadjuvant HD P6 regimen (high-dose cyclophosphamide, doxorubicin, and vincristine (HD-CAV) alternating with ifosfamide and etoposide (IE) chemotherapy combined with aggressively attempted R0 resection). We aimed to review the molecular characteristics of DSRCTs to explore therapeutic opportunities for this extremely rare and aggressive cancer type.

Extensive Abdominopelvic Desmoplastic Small Round Cell Tumor — Case Report and Review of the Literature

Desmoplastic small round cell tumor (DSRCT) is a rare malignant tumor, which affects mostly young males and has a poor prognosis. Since 1991, when it was first described as a distinct clinical entity by Gerald WL and Rosai J, some 200 cases were reported. DSRCT arises mainly from the abdominal and pelvic cavity, causes abdominal pain or discomfort, weight loss, urinary, bowel or bile obstruction due to compression. Metastases appear most frequently in the liver and lungs. Multimodal therapy is usually indicated with chemotherapy, surgery, radiotherapy and autologous stem cell transplantation. DSRCT should be differentiated from other small, blue round cell tumors, especially hematopoietic malignancies (leukemia, lymphoma), neuroblastoma, Ewing sarcoma, PNET, rhabdomyosarcoma, malignant mesothelioma, small cell carcinoma and Wilms tumors. We report the case of a patient with an extensive abdominopelvic desmoplastic small round cell tumor, with liver metastases, in an adolescent male patient, highlighting the alert deterioration of the clinical status of the patient after the biopsy, the need for a second review of the histopathological material in order to obtain a correct diagnosis, the chemoresistance of the tumor despite an apparently good clinical status, and the severe prognosis of this type of tumor.

Birth and evolution of the desmoplastic small round-cell tumor

The first large series of desmoplastic small round cell tumor was reported twenty-five years ago. This article reviews the original characterization of this neoplasm, and the eventual expansion of its clinical and pathological spectrum. Relevant data on its molecular features are summarized, in order to understand the search for therapeutic targets. The challenge ahead is to better know and cure this disease through the finding and validation of actionable therapeutic targets.

A Rare Case of Metastatic Desmoplastic Small Round Cell Tumour: Diagnosis and Management

A 26-year-old male without any significant past medical history presented to the hospital with shortness of breath, cough, pleuritic chest pain, and weight loss for the past 3 months. On chest CT, he was found to have extensive mediastinal and hilar lymphadenopathy and multiple pulmonary nodules. On physical examination, a right groin mass was noted which had been slowly growing for the past 2 years. Ultrasound of the groin showed complex solid mass with internal vascular channels. CT guided biopsy of the mass showed desmoplastic small round cell tumour. His hospital course was complicated by hypoxic respiratory failure requiring emergent intubation and ICU admission where he completed one cycle of vincristine, cyclophosphamide, and doxorubicin with subsequent improvement, followed by extubation. His condition continued to improve after second cycle of chemotherapy and he was ultimately discharged in a stable condition to continue outpatient chemotherapy after a 2-month inpatient stay.

Merkel cell carcinoma presenting as malignant ascites: A case report and review of literature

The most common site of metastasis to ascitic fluid in females is from a mullerian (ovarian) primary, whereas in males it is from the gastrointestinal tract. Metastatic Merkel cell carcinoma (MCC) to the ascitic fluid is extremely rare and may present as a diagnostic challenge on effusion cytology. In a review of the literature, there are only two case reports of metastatic MCC in pleural effusion. To the best of our knowledge, we present the first cytological diagnosis of MCC metastatic to the ascitic fluid. We describe the cytologic findings as well as the immunohistochemical stains supportive of the diagnosis. Given the fatal prognosis of this tumor compared to melanoma and rarity of its occurrence in ascitic fluid, awareness of this tumor and use of immunohistochemical stains are critical in arriving at the diagnosis.