Spectrum of cytopathologic features of epithelioid sarcoma in a series of 7 uncommon cases with immunohistochemical results, including loss of INI1/SMARCB1 in two test cases

A unique case of epithelioid sarcoma involving the mandibular alveolar mucosa

Epithelioid sarcoma (ES) is an infrequent, malignant, mesenchymal, soft-tissue neoplasm of uncertain histogenesis characterized by epithelioid cytomorphology. The lack of SMARCB1/INI1 (Integrase interactor 1) expression typifies this pathology. It usually presents as a painless, indolent, slowly enlarging lesion or rarely as an aggressive growth. Epithelioid sarcoma affects mostly pediatric patients or young adults. It recurs quite frequently and possesses a high degree of metastatic potential. Two predominant histomorphologic patterns include classic/conventional type and proximal types. Epithelioid sarcoma immunohistochemically shows vimentin, cytokeratin, epithelial membrane antigen, CD34 positivity, and negative staining with S100 and desmin. Management is generally multimodal, including wide surgical resection, radiotherapy, and chemotherapy. To date, to our knowledge, only 11 instances of head and neck ES have been reported in the literature. Our case deals with the diagnosis of intraoral ES in a 55-year-old female patient, probably the first one to involve the mandibular mucosa, based on relevant clinical-radiologic-pathologic-immunohistochemical findings.

Pitfalls in soft tissue cytopathology

Fine needle aspiration biopsy (FNAB) is a diagnostic modality for the evaluation of suspicious soft tissue masses. Despite its reasonable sensitivity, specificity and positive predictive value in differentiating benign from malignant neoplasms, the exact subtyping of the primary soft tissue tumours can be challenging. Certain tumours constitute "pitfalls" and add to the diagnostic challenge. This review provides a detailed account of the diagnostic challenges in soft tissue cytopathology, including pitfalls and, more importantly, the ways to overcome these challenges by integrating clinical details, key cytomorphological features and judicious application of ancillary techniques.

Myoepithelial carcinoma of soft tissue is a diagnostic challenge on fine-needle aspiration: Case report and review of literature

Myoepithelial carcinoma (MEC) of soft tissue, also known as malignant myoepithelial tumor, is an uncommon malignancy. Cytologic diagnosis of this entity is challenging due to its rarity and heterogeneous morphology. We report a case of MEC in a 22-year-old man, who presented with a 6.5 cm soft tissue mass on his right distal forearm that has been enlarging over the past 3 months. Ultrasound-guided fine-needle aspiration (FNA) revealed abundant isolated neoplastic cells ranging from spindled cells to epithelioid and plasmacytoid morphology in a myxoid background. These cells showed moderate cytologic atypia characterized by high-nuclear/cytoplasmic ratio, irregular nuclear contours, and prominent nucleoli. The cytoplasm varied from dense to vacuolated and occasionally rhabdoid with intracytoplasmic inclusions. Scattered bi- and multinucleated cells were identified. A diagnosis of high-grade malignancy was made with the differential diagnosis including rhabdomyosarcoma and melanoma. A subsequent core biopsy of the tumor showed immunoreactivity for pan-cytokeratins, calponin, p63, and smooth muscle actin. INI-1 was lost. SOX-10 and Melan-A were negative. Molecular studies showed loss of SMARCB1 (INI-1) and CDKN2A. Gene fusion studies did not detect any fusion. A diagnosis of soft tissue MEC was made which is a challenge on FNA due to several cytologic mimickers including rhabdomyosarcoma, epithelioid sarcoma, extrarenal rhabdoid tumor, extra-axial chordoma and melanoma. Recognition of the biphasic cell population in a myxoid background and a battery of immunohistochemical stains are crucial for accurate diagnosis.

Epithelioid sarcoma of the hand: a wolf in sheep's clothing

Epithelioid sarcoma (ES) of the hand is a rare, aggressive cutaneous malignancy with high rates of recurrence, metastases and mortality. With an incidence rate of 0.4 cases/y per one million population, which compromise for approximately 1-1.4% of all soft tissue sarcoma, ES accounts for 10% of soft tissues sarcomas of the hand and foot. Its aggressiveness and propensity to spread and metastases without being noticed, makes it unique and potentially lethal. Missed or delayed diagnosis are often encountered as this tumor can mimic variety of different entities and due to the infrequent nature of this lesion, treatment options are still controversial. The authors provide systemic review of the current literature on epidemiology, etiology, pathogenesis, management and outcomes of this disease as well as a case presentation and a proposed treatment algorithm. The choice of treatment option depends on disease characteristics, staging at presentation, regional lymph node involvement, comorbidities and performance status of the patient. Emphasis on a multidisciplinary coordinated care is crucial as early diagnosis and treatment can decrease morbidity and mortality rates.

Revisiting cytomorphology, including unusual features and clinical scenarios of 8 cases of alveolar soft part sarcoma with TFE3 immunohistochemical staining in 7 cases

OBJECTIVES

To present a comprehensive analysis of cytomorphological features, including clinical scenarios, for 8 cases (4 males, 4 females, aged 17-39 years, average = 28.5) of, retrospectively diagnosed alveolar soft part sarcoma (ASPS), with TFE3 immunostaining in 7 cases.

METHODS

Conventional Papanicolaou and May Grunwald-Giemsa (MGG) stained smears and corresponding tissue sections were critically reviewed. Fine needle aspiration cytology was performed for primary diagnosis in 6 cases and for metastatic lesions in 2 cases. TFE3 and other immunohistochemical stains were tested using polymer detection technique.

RESULTS

Tumour sites were thigh (n = 6), shoulder (1) and neck (1). Tumour size (n = 6) varied from 5 to 14.5 cm (average = 7.2). Seven out of 8 cases were correctly diagnosed on cytosmears. The smears were mostly hypercellular (5), composed of cohesive clusters (8), including cell balls and pseudopapillae (3) and singly scattered cells (8). Tumour cells were round to oval, containing central to eccentric nuclei (8), abundant granular (8) to finely vacuolated (7) cytoplasm that was ill- to well-defined, intracytoplasmic rod-like or needle-shaped crystals (3) and prominent nucleoli (8), Additionally, there were binucleated cells (7), multinucleation (2), intracytoplasmic inclusions (3), intranuclear inclusions (2), intercellular stroma (5) and bare nuclei (8). Immunohistochemically, 7/8 tumours were positive for TFE3.

CONCLUSIONS

This constitutes the largest series describing cytomorphological spectrum of ASPS with TFE3 immunostaining results. Frequently observed features and rod-like/needle-shaped crystals on MGG smears, can help to differentiate ASPS from its mimics. TFE3 immunostaining aids in substantiating diagnoses, in an appropriate clinicoradiological context.

Cytomorphological features of an unusual case of a multifocal pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma in a young adult male

Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma (PMHE) is a relatively newly described vascular neoplasm, characterized by distinct clinicopathological and molecular features, with no report on its cytomorphological features on smears, till date. A 17-year-old male presented with multiple nodules on his left upper limb. Radiologic imaging disclosed multiple lesions involving the soft tissues, skin, and bones of his left upper limb. Biopsy of one of the lesions on his left ring finger revealed a cellular tumor comprising plump spindle and epithelioid cells, containing moderate to abundant, eosinophilic cytoplasm; mild nuclear atypia, vesicular nuclear chromatin, discernible nucleoli, infrequent mitotic figures, and interspersed neutrophils. Immunohistochemically, tumor cells were positive for AE1/AE3, CD31, and FLI-1, while negative for CD34 and desmin. INI1/SMARCB1 was retained. MIB1/Ki67 highlighted nearly 3% tumor cells (low). Diagnosis of a PMHE was offered. A simultaneous fine needle aspiration cytology smears of the lesions in his left forearm and ipsilateral axillary region revealed spindle and some polygonal shaped cells, arranged in tight and loose clusters, as well as scattered singly, containing abundant cytoplasm with tapering cell membranes, at places; vesicular nuclear chromatin and characteristic intercellular fibrillary stromal material. The present case constitutes the first report on cytomorphological features of a PMHE, diagnosed on cytology, including its differential diagnoses, immunohistochemical features with molecular updates.

Cytomorphological spectrum, including immunohistochemical results of 16 cases of clear cell sarcoma of soft tissue, along with positive EWSR1 gene rearrangement result in two cases

OBJECTIVES

To describe the cytopathological features of clear cell sarcomas (CCSs), including immunohistochemical and molecular results, the latter in selected cases.

METHODS

Sixteen consecutively diagnosed cases of CCS of soft tissue, over 6-year duration were included. Fine needle aspiration cytology was performed for primary diagnosis in three and for recurrent/metastatic lesions in 12 cases. Cytopathological features in 16 cases (conventional Papanicolaou- and May-Grünwald Giemsa-stained smears) were critically analysed. Corresponding histopathological and immunostained sections were available in 15 cases. Two cases were tested for EWSR1 gene rearrangement by fluorescence in-situ hybridisation.

RESULTS

Sixteen tumours occurred in patients with age ranging from 18 to 56 years (median = 33.5); M: F ratio = 1:1; in deep soft tissues, mostly in extremities. Primary cytopathological diagnosis (3 cases) was CCS with a differential diagnosis of melanoma (1 case) and poorly differentiated malignant tumour (2 cases). On review, smears were predominantly hypercellular (n = 14), invariably composed of monomorphic appearing epithelioid/polygonal cells (n = 16), including spindle cells (n = 6); mostly singly scattered (n = 16), in loose clusters (n = 12); with prominent nucleolisation (n = 16); granular to vacuolated, well-defined cytoplasm (n = 12), binucleation/multinucleation (n = 9); mitoses (n = 6); sudden anisonucleosis; racquet-shaped cells (n = 3), against a tigroid background (n = 2), along with focal intracytoplasmic pigment deposition (n = 2). Immunohistochemically, tumour cells were positive for S-100P (15/15), HMB-45 (15/15) and melan-A(6/12). Two cases tested for EWSR1 rearrangement displayed red-green split signals.

CONCLUSIONS

This constitutes one of the largest series describing the cytomorphological spectrum of CCS of soft tissue. Certain features, such as singly scattered monomorphic, epithelioid cells with prominent nucleolisation are useful diagnostic clues. Immunohistochemical stains are necessary and molecular testing is further helpful in reinforcing a diagnosis in certain cases. A correct diagnosis has crucial treatment implications.

Cytopathology of classic type epithelioid sarcoma: a series of 20 cases and review of the literature

INTRODUCTION

As a rare soft tissue malignancy, epithelioid sarcoma (EpS) is infrequently subjected to cytopathologic analysis. With the exception of a few series, the cytology literature regarding EpS is largely limited to single case reports. Our purpose was to evaluate our experience with EpS, and review the literature regarding its cytopathology.

MATERIALS AND METHODS

A search was made of our cytopathology and surgical pathology databases for cases diagnosed as EpS. Fine-needle aspiration biopsy smears and imprint smears were performed and examined using standard technique. Effusion samples were processed using liquid-based slides.

RESULTS

Twenty cases of EpS were retrieved from 10 patients (M:F 1:1; mean age = 36 years). One patient had 5, 1 patient had 3, and 3 patients had 2 separate specimens. All patients had prior or subsequent tissue confirmation of EpS; all were of the classic/distal type. Seven were new patient cases, 7 were locally recurrent, and 6 were metastases. Sites included lower extremity (8 cases), upper extremity (4), trunk (4), serous effusion (2), scalp (1), and mediastinum (1). Specific cytologic diagnosis were EpS (13 cases), sarcoma not otherwise specified (5), and malignant neoplasm (2). All cases where cell-block SMARCB-1 staining was used were specifically recognized as EpS. Cytomorphology was composed primarily of epithelioid/plasmacytoid cells having eccentrically positioned nuclei, moderate cytoplasm, and variable nuclear pleomorphism.

CONCLUSION

The cytopathology of EpS is somewhat variable, morphologically non-specific, and mimics that of other neoplasms with epithelioid features. Ancillary immunostaining is necessary for a specific diagnosis in newly encountered patients.

Core Needle Biopsy versus Fine Needle Aspiration Cytology in Bone and Soft Tissue Tumors

Fine needle aspiration cytology (FNAC) for diagnosis of musculoskeletal tumors is well discussed and debated. The current evidence restricts its application in recurrent and metastatic lesions, with core needle biopsy as the acceptable technique/gold standard for the primary diagnosis of these challenging tumors. However, there are several studies showing reasonable sensitivity and specificity in primary diagnosis of bone and soft tissue tumors, especially in differentiating benign from malignant tumors. There is an acceptable limitation in the exact subtyping of soft tissue tumors, based on cytology smear examination, in the absence of ancillary techniques. Nonetheless, cytology constitutes an optimal material for triaging cases for ancillary techniques, such as immunocytochemistry, immunohistochemistry, molecular cytogenetics, and molecular diagnosis, in the form of smears and cell block preparations. This review focuses on the strengths and limitations of cytology versus core needle biopsy in the diagnosis of bone and soft tissue tumors, with the current evidence in the form of published studies, including the authors' experience.

FNA of epithelioid sarcoma: Curie Institute experience and critical review of the literature

BACKGROUND

Epithelioid sarcoma (ES) is a rare mesenchymal tumor that is divided into 2 types: classic and proximal. To the authors' knowledge, ES has been poorly studied in cytology, with fewer than 50 cases reported to date. The objective of the current study was to analyze the cytological and immunohistochemical information regarding 5 cases of ES.

METHODS

Five cases of ES were analyzed: 4 of proximal type and 1 of classic type. The cases were taken from 4 female patients and 1 male patient. The patients ranged in age from 10 to 75 years.

RESULTS

All smears obtained from the proximal type of ES were found to be hypercellular with a necrotic and inflammatory background. Smears from classic-type ES were hypocellular with a hemorrhagic background. Large, dispersed epithelioid cells and loosely cohesive groups of cells were most frequently noted in all cases. All cases of proximal-type ES demonstrated rhabdoid cells and marked nuclear atypia, but in only one case were rhabdoid cells found to be dominant. ES diagnoses were confirmed by immunohistochemistry in histological material. In 4 cases, epithelial marker expression was noted, whereas CD34 was found to be positive in only the classic type of ES. In 2 cases, total loss of SMARCB1/INI1 nuclear expression was observed. In the 2 SMARCB1/INI1-positive cases, loss of SMARCA2/BRM expression was observed in one case and partial loss was observed in the other case.

CONCLUSIONS

The proximal type of ES differs from the classic type by the presence of rhabdoid cells and marked nuclear atypia. A specific immunohistochemical profile demonstrating loss of SMARCB1/INI1 or other proteins from the SWI/SNF complex also may be indicative of this diagnosis.

Cytologic Features of SMARCA4-Deficient Thoracic Sarcoma: A Case Report and Comparison with Other SWI/SNF Complex-Deficient Tumors

BACKGROUND

SMARCA4-deficient thoracic sarcoma is a recently proposed entity of soft tissue tumors associated with an extremely poor prognosis. Its cytologic features have not been well described in the literature yet.

CASE

A woman in her early 30s who presented with chest pain was found to have a tumor in the right chest wall. Cytologic smears revealed numerous atypical round-to-polygonal cells appearing singly or in loosely cohesive clusters. These cells had a well-defined cell border, scant-to-moderate cytoplasm, and enlarged vesicular nuclei with prominent nucleoli. In addition, some cells with eosinophilic globular intracytoplasmic inclusions and eccentrically located nuclei, consistent with rhabdoid cells, were observed. Immunocytochemically, the cells were at least focally positive for cytokeratin CAM5.2 and CD34 and showed a significantly reduced BRG1/SMARCA4 expression. The diagnosis was confirmed by histological, immunohistochemical, and genetic analysis of a metastatic lesion to the left axillary lymph node.

CONCLUSION

Although the cytologic features of SMARCA4-deficient thoracic sarcoma are not fully unique, they are sufficiently characteristic to suspect this tumor in cases of supporting clinical and radiological features, which may promote additional immunological or molecular testing to establish a definitive 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.