Diagnostic pitfalls associated with fine-needle aspiration biopsy in a patient with the myxoid variant of monophasic fibrous synovial sarcoma

Synovial sarcoma (SS) is one of the most common soft tissue tumors that typically presents in the extremities of young adults, but may occur at any site and affect children during the first decade. Herein we discuss a 12-yr-old male who complained of left foot pain and plantar mass. A fine-needle aspiration biopsy of an 8 cm subcutaneous mass was performed revealing a myxoid spindle cell neoplasm. The cytologic differential diagnosis included a myxoid neurofibroma, neurothekeoma, and a myxoid sarcoma. Subsequent excision of the mass revealed a monophasic fibrous SS with myxoid features. Examination of the tissue by fluorescence in situ hybridization confirmed the presence of characteristic SS SYT gene rearrangement at chromosome 18q11.2. This case underscores that the cytologic distinction of mxyoid spindle cell tumors may be challenging. We report the cytologic features of a myxoid monophasic fibrous SS, and discuss its distinction from other benign and malignant myxoid soft tissue neoplasms.     

Diagnosis of recurrent synovial sarcoma by fine needle aspiration cytology--a case report

Cytodiagnosis of synovial sarcoma can be a daunting task, owing to the varied cytomorphological appearances possible, depending on whether the tumour is monophasic or biphasic in architecture. We report herewith a case of recurrent synovial sarcoma in a young male who presented with a swelling in the neck. The diagnosis was established by fine needle aspiration cytology.     

Fine‐needle aspiration cytology of extraskeletal myxoid chondrosarcoma: A case report

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue tumor arising in extremities. We report a typical case of EMC in left inguinal region of a 71‐year‐old man, which was first approached by fine‐needle aspiration, followed by surgical excision and subsequently diagnosed by microscopic examination and immunohistochemical study. We discuss briefly the differential diagnosis. It is important to separate EMC from other myxoid soft tissue tumors. We point out that although cytologic features may be orientating to a myxoid tumor, may not be completely distinctive. Diagn. Cytopathol. 2010. © 2009 Wiley‐Liss, Inc.     

Low-grade pulmonary myxoid sarcoma of uncertain histogenesis

The present report describes an unusual case of low-grade pulmonary sarcoma with extensive myxoid change in a 60-year-old man. During 30 months, the tumor enlarged gradually and thereafter rapidly to 9 cm. Preoperative biopsy and cytology gave negative results. The resected mass, located at the periphery of the right upper lobe, was well circumscribed and showed gelatinous without necrosis or hemorrhage. Histologically, the tumor was composed of slightly atypical, spindle-shaped or stellate cells, which were loosely distributed within a prominent myxoid stroma. Epithelial differentiation was not seen. Lacunar structures were occasionally evident, but no cartilaginous matrix was seen. Mitotic figures were infrequent. Immunohistochemistry failed to clarify the nature of the neoplastic cells except vimentin positivity. Histochemically, the myxoid ground substance was composed of hyaluronic acid and acid mucopolysaccharide. Electron microscopy revealed no specific differentiation other than aggregates of filaments, which were seen in a number of neoplastic cells. Flow cytometric analysis of the neoplastic cells revealed a diploid pattern. These findings indicated that the neoplasm was a low-grade myxoid sarcoma; however, a definite diagnosis could not be made. The tumor might have been a variant of extraskeletal myxoid chondrosarcoma, especially considering the histochemical results.     

Malignant melanoma with a myxoid stroma: a diagnostic pitfall on fine-needle aspiration biopsy

Malignant melanoma (MM), both primary and metastatic, may be associated with a prominent myxoid stromal reaction causing diagnostic confusion on fine-needle aspiration biopsy (FNAB), most often with sarcomas that demonstrate a myxoid stroma, particularly malignant peripheral nerve sheath tumor (MPNST). We present a case of a 32-yr-old man with no past medical history who presented with a unilateral neck mass clinically suspicious for lymphoma. FNAB produced a specimen composed of large sheets of anaplastic cells encased in a myxoid stroma that was S100 and vimentin-positive but HMB-45-negative. A diagnosis of MPNST was made. Excision demonstrated a metastatic MM of unknown primary, with a prominent myxoid stromal reaction. A repeat HMB-45 was again negative. Electron microscopy demonstrated intracytoplasmic melanasomes and cisternae of rough endoplasmic reticulum with intracisternal parallel tubules, confirming the diagnosis. Although HMB-45 is typically negative in both tumors, S100 should be strongly positive in myxoid MM and only focal in MPNST.     

Fine‐needle aspiration biopsy of prostate synovial sarcoma: A case report and review of the literature

We describe a case of synovial sarcoma originating from prostate gland. The diagnosis was confirmed by fluorescent in situ hybridization analysis (FISH) for SYT rearrangement on the cell block. Synovial sarcoma is a high grade soft tissue malignancy with exceedingly rare involvement of genitourinary tract. However this entity should be considered in the differential diagnosis when dealing with aspiration biopsies of particularly deep seated lesions with spindle cell or small round blue cell cytomorphology. Diagn. Cytopathol. 2017;45:168–172. © 2016 Wiley Periodicals, Inc.     

Cytologic findings of myxoid neurothekeoma: case report based on fine-needle aspiration cytology,immunohistochemistry, and correlating histopathology

Myxoid neurothekeomas (nerve sheath myxomas) are rare benign cutaneous neoplasms that may morphologically mimic other myxoid neoplasms of skin and soft tissue. The cytologic and histopathologic features of this lesion may resemble various myxoid sarcomas, chordoma, myxoid neurofibroma, dermal cutaneous mucinosis, and cutaneous myxoma as well as other myxoid or chondroid neoplasms. In this study, a myxoid neurothekeoma was analyzed using multiple techniques. We found that myxoid neurothekeomas reveal a nonspecific pattern by fine-needle aspiration, including stellate cells embedded within an abundant metachromatic myxoid stromal matrix. These are cytologic features shared by various other subcutaneous neoplasms and thus may not be helpful in forming a definitive diagnosis. Histopathologically, the tumor is composed of nodules of myxoid stroma containing interspersed bland spindled and stellate cells. Immunohistochemical studies show tumor cell positivity for S-100 protein and vimentin, a profile shared by other neoplasms with similar cytologic features and therefore of little diagnostic value. The histologic and cytologic differential of subcutaneous and soft tissue myxomatous lesions is broad and, therefore, is of unique value to the cytopathologist to consider myxoid neurothekeomas among the differential of other myxomatous neoplasms.     

Low-grade periductal stromal sarcoma of the breast with myxoid features: Immunohistochemistry

A 52-year-old woman was admitted with a painful right breast tumor measuring more than 20 cm in largest diameter, which ulcerated the overlying skin. The lesion had appeared 4 years previously but the patient hesitated to seek medical care due to 'fear of cancer'. Microscopically, the tumor was composed of spindle cells that formed cuffs around multiple open tubules and ducts set in an abundant, myxoid stroma. The spindle cells had significant atypia with nuclear pleomorphism, occasional cytoplasmic vacuolation and moderate mitotic activity. The ducts and lobules surrounded by the proliferating tumor cells had minimal distortion, with a pericanalicular growth pattern devoid of the phyllodes pattern. The tumor had a multinodular growth pattern with coalesced and individual tumor nodules, the latter being found mostly at the periphery of the lesion. On immunohistochemistry the tumor cells were positive for smooth muscle actin, CD34, and vimentin, and focally positive for CD10. A diagnosis of low-grade periductal stromal sarcoma (PDSS) with myxoid features was established. PDSS is a distinct low-grade breast sarcoma, the appropriate diagnosis of which requires extensive tumor sampling and additional broad immunohistochemistry. PDSS should not be confused with other spindle cell breast tumors because they require different treatment.     

Intra-abdominal synovial sarcoma: a clinicopathological study

AIMS: To evaluate a series of synovial sarcomas arising in the abdomen, pelvic cavity, or retroperitoneum. Synovial sarcoma is rare within the abdomen. In this location, it can be confused with other biphasic tumours and with other spindle and round cell sarcomas. METHODS AND RESULTS: Cases were retrieved from archives. There were 11 intra-abdominal tumours among 300 synovial sarcomas in two referral practices (3.7%). Three were pelvic (two midline, one sidewall) and eight were retroperitoneal. They occurred in six males and five females aged from 25 to 75 years (mean 49 years, median 46 years), and ranged in diameter from 65 to 470 mm (mean 210 mm, median 150 mm). Six examples were biphasic, five were monophasic and seven had poorly differentiated areas. Monophasic tumours displayed at least one epithelial marker. One biphasic tumour had a SYT-SSX2 fusion gene. Seven sarcomas were high-grade and four of intermediate grade malignancy. Follow-up data were available in 10 patients. In all but one case, tumour recurred or metastasized within the abdomen. The pelvic sarcomas also metastasized outside the abdomen. Eight of 10 patients (80%) died of disease with survival from 4 to 36 months (mean 17 months, median 18 months). Two patients were alive with disease at 43 and 48 months. CONCLUSIONS: Synovial sarcomas rarely arise within the abdomen and pelvis. They occur mainly in middle age, attain a large size, are difficult to excise and recur locally. Pelvic tumours metastasize distantly. Retroperitoneal tumours remain confined to the abdomen and, unlike synovial sarcomas elsewhere, do not metastasize remotely, although mortality is high.     

Identification of poorly differentiated synovial sarcoma: a comparison of clinicopathological and cytogenetic features with those of typical synovial sarcoma

AIMS: Poorly differentiated areas in synovial sarcomas (SS) are known to be associated with a poorer prognosis. The aim of our study was to describe the morphological spectrum of poorly differentiated synovial sarcomas (PDSS) and refine the criteria for their recognition. METHODS AND RESULTS: The clinicopathological features of 28 PDSS were compared with those of 26 classic SS. Common cell types in PDSS included epithelioid, spindle and Ewing sarcoma-like small round cells. Unusual features included presence of desmoplastic small cell tumour-like areas and extraskeletal myxoid chondrosarcoma-like areas. The presence of necrosis (P = 0.002), a mitotic rate over 10/10 high-power fields (P < 0.001), a haemangiopericytomatous vascular pattern (P < 0.001) and vascular invasion (P = 0.003) were significantly associated with PDSS, while mast cells (P < 0.001), calcification (P < 0.001) and hyaline bands (P < 0.001) were significantly associated with classic SS. Poorly differentiated areas showed increased proliferative activity with Ki67. PDSS showed a tendency to be larger (P = 0.008) and to be located in proximal more than distal sites (P = 0.025). Three entirely poorly differentiated tumours were diagnosed by demonstration of the t(X;18)(p11;q11) translocation. PDSS showed additional cytogenetic abnormalities. CONCLUSIONS: Poorly differentiated synovial sarcomas show a spectrum of histological features, which may simulate other malignant neoplasms. The diagnosis of entirely poorly differentiated synovial sarcomas requires cytogenetic analysis.     

Fine needle aspiration of primary mediastinal synovial sarcoma: Cytomorphologic,immunohistochemical, and molecular study

The cytologic diagnosis of synovial sarcoma (SS) can be difficult when it occurs in unusual locations, atypical age groups, and/or have unusual morphology. We report a case of primary mediastinal SS in a 65‐year‐old male with a long smoking history who presented with increasing shortness of breath and was found to have a 14.2 cm mediastinal mass. Smears from the endobronchial ultrasound guided fine needle aspiration of the mass were moderately cellular consisting of loosely cohesive clusters, some of which demonstrated nuclear molding, and dispersed single cells. The relatively uniform tumor cells had a high nuclear‐to‐cytoplasmic ratio, finely granular chromatin, and inconspicuous nucleoli. Some of the single cells had spindled morphology with unipolar wispy tails and naked nuclei. Based on the clinical presentation and the cytomorphologic features, our initial differential diagnoses included atypical carcinoid, small cell carcinoma, basaloid squamous cell carcinoma, sarcoma, and lymphoma. Immunohistochemical studies on the cell block sections revealed that the tumor cells were focally positive for cytokeratin and diffusely positive for CD56, while negative for CD45, synaptophysin and chromogranin. Ultimately, an immunohistochemical stain for TLE‐1 demonstrated diffusely strong nuclear positivity and molecular studies showed the presence of the t(X; 18) SYT/SSX1 translocation confirming the diagnosis of SS. In this report, we describe the cytomorphologic features of SS, its diagnostic pitfalls, and potential mimics in the mediastinum. Diagn. Cytopathol. 2014;42:170–176. © 2012 Wiley Periodicals, Inc.     

Biphasic axillary synovial sarcoma diagnosed by preoperative fine‐needle aspiration cytology

Synovial sarcoma (SS) is a soft‐tissue sarcoma which usually occurs in lower extremities. Less than 20 cases of SS located in shoulder or axillary region have been reported, and these studies describe histopathological features. We report a case of axillary SS diagnosed by fine‐needle aspiration cytology, immunocytochemistry, and molecular techniques performed on cytology smears. A 48‐year‐old woman presented with a palpable and well‐defined axillary mass which measured 4 cm. On‐site smears showed high cellularity with spindle cells, and a mesenchymal tumor was suspected. Definitive cytological analysis showed cells with ovoid‐ or comma‐shaped nuclei arranged in loose sheets and fascicles, associated with naked nuclei and isolated cells. Mitotic count was 2 mitoses/HPF. Immunocytochemical studies showed vimentin and focal CK AE1‐AE3 positivity. A PCR was performed and the specific translocation t (X;18) was detected. The lesion was excised and the diagnosis of biphasic SS was confirmed. The identification of SS on cytology specimens is difficult and differential diagnosis is broad. Complementary studies are necessary and they can be performed on FNA smears or cell blocks.     

Pulmonary synovial sarcoma with polypoid endobronchial growth: a case report, immunohistochemical and cytogenetic study

A rare case of primary pulmonary synovial sarcoma with polypoid endobronchial growth in a 42-year-old Japanese woman is described. Left upper sleeve lobectomy was performed for the polypoid tumor measuring 2.5 cm in the left major bronchus and the patient was treated with adjuvant chemotherapy. Three years later, a recurrent tumor was discovered. Microscopically, this tumor was characterized by a proliferation of oval to spindle-shaped cells arranged in sheets and fascicles and covered by the thin normal bronchial epithelium. Immunohistochemically, tumor cells were positive for vimentin, and focally positive for pancytokeratin recognized by AE1/AE3, cytokeratin 7 and epithelial membrane antigen. A chimera gene, SYT-SSX1, was detected. Recently, primary pulmonary synovial sarcoma is an increasingly recognized clinical entity; however, most of these tumors present as a parenchymal mass. The present case is a unique example of primary synovial sarcoma of endobronchial polypoid type. This case suggests that pulmonary synovial sarcoma might originate from bronchial submucosal stromal tissue.     

Fine needle aspiration of secondary synovial sarcoma of the thyroid gland

Synovial sarcomas (SS) of the head and neck region are extremely rare and arise in only 5% of cases. We present a case of secondary SS of the thyroid originally diagnosed as medullary carcinoma on fine needle aspiration (FNA). A 41‐year‐old man presented with several weeks of dysphonia and a left thyroid mass. FNA of the thyroid nodule showed a cellular smear composed of loosely cohesive oval to spindle‐shaped cells with irregular nuclear borders, finely granular chromatin, and inconspicuous nucleoli. The patient was diagnosed with medullary carcinoma and underwent a total thyroidectomy. Intro‐operatively, the mass was found to arise from the tracheoesophageal groove with spread to the left thyroid. Microscopic examination of the thyroid tumor revealed a dense spindle cell proliferation with abundant mitoses, scant cords and nests of epithelial cells and foci of necrosis. The spindle cells were positive for bcl2 and vimentin and the epithelial cells were positive for cytokeratin 8/18 and epithelial membrane antigen (EMA). Both spindle and epithelial cells were negative for thyroglobulin, calcitonin, synaptophysin and chromogranin. Fluorescence in situ hybridization (FISH) demonstrated translocation (X;18)(p11;q11), confirming the diagnosis of SS. The patient underwent a total laryngopharyngoesophagectomy with subsequent adjuvant therapy and is currently disease free. Only 6 cases of histologically confirmed primary SS of the thyroid have been reported. To the best of our knowledge, this is the first case of FISH‐confirmed secondary SS of the thyroid and also the first case of SS arising from the tracheoesophageal groove. Diagn. Cytopathol. 2015;43:928–932. © 2015 Wiley Periodicals, Inc.     

Monophasic parapharyngeal synovial sarcoma diagnosed by cytology, immunocytochemistry, and molecular pathology: case report and review of the literature

Synovial sarcoma (SS) of the head and neck region are rare, accounting for less than 10% of all head and neck soft tissue sarcomas. A limited number of SS have been reported in the parapharyngeal space and these reports have all been based on histological examination of resection material. The diagnosis of monophasic SS on cytology is extremely difficult. We report the first case where a SS was correctly diagnosed on a fine needle aspirate by cytology with the assistance of immunocytochemistry and fluorescence in situ hybridization. We will emphasize the importance of ancillary techniques, such as immunocytochemistry and cytogenetic/molecular pathology, in avoiding diagnostic pitfalls and correctly diagnosing monophasic SS on cytologic material. We will propose an algorithmic approach to accurately diagnose parapharyngeal spindle cell neoplasms with the use of appropriate ancillary studies in conjunction to morphological features.     

Fine needle aspiration of malignant melanoma with myxoid features: A case report with molecular analysis

Malignant melanoma with myxoid features (MMM) is a rare melanoma variant in which tumor cells are embedded within a basophilic myxoid stroma. The stromal matrix is composed of acidic mucopolysaccharides, which are thought to be produced by mesenchymal stromal cells in response to melanoma invasion. Interestingly, this myxoid matrix is more often seen in metastasis from a primary tumor that does not have a myxoid stroma. The diagnosis of MMM on fine needle aspiration (FNA) can be confused with other myxoid tumors. Herein, we present a case of MMM diagnosed by FNA of a peri‐auricular lymph node in an 89‐year‐old man with a history of resected malignant melanoma. We describe the clinical, cytohistological, and immunohistochemical findings, and present the unique molecular alterations that were identified. We also discuss the differential diagnosis and potential diagnostic pitfalls associated with MMM.     

Monophasic synovial sarcoma, epithelioid sarcoma and chordoid sarcoma: ultrastructural evidence for a common histogenesis, despite light microscopic diversity

Ultrastructural examination of six rare sarcomas-four monophasic spindle cell tumours, one epithelioid sarcoma, one chordoid sarcoma-has revealed marked similarities at the electron microscopic level despite widely divergent light microscopic appearances. These features consisted of: 1 the presence of two cell types, viz. a clear cell and a cell resembling the fibroblast; 2 pseudoglandular spaces with projecting microvilli or filopodia, and with related tight junctions; 3 an amorphous intercellular ground substance with focal condensation into recognizable basement membrane. The findings suggest a common maturation of these diverse tumours to synovial-like tissue, and support the proposal of Hajdu Shiu & Fortner (1977) that these be considered variants of synovial sarcoma. Published ultrastructural studies of synovial, epithelioid and chordoid sarcoma are reviewed in the light of these findings. The ultrastructural differentiation of synovial sarcoma from extra-skeletal myxoid chondrosarcoma, chordoma and the spectrum of malignant spindle cell tumours is discussed.