Fine-needle aspiration cytology of malignant nerve sheath tumors

The cytopathology of malignant peripheral nerve sheath tumor: a report of 55 fine-needle aspiration cases

BACKGROUND

Among sarcomas, a diagnosis of malignant peripheral nerve sheath tumor (MPNST) is often one of exclusion due to the absence of unequivocally characteristic histopathology, a conclusive immunohistochemical profile, or even a unique chromosomal anomaly. Because of this, the fine-needle aspiration (FNA) cytopathology of MPNST is extremely challenging. In the current study, the authors review their FNA experience with this neoplasm.

METHODS

The authors searched their combined departmental cytology files for all lesions signed out as MPNST or suspicious for MPNST, as well as their own surgical pathology files for any cases of MPNST that had corresponding cytology. FNA was performed using standard techniques.

RESULTS

A total of 55 cases of MPNST, all with tissue confirmation, and 1 misdiagnosed example of melanoma were retrieved from 52 patients (M:F ratio of 1.5:1; average age, 46 years), 26 of whom had a history of neurofibromatosis type 1 (NF-1). Aspirates were from primary (27 cases), locally recurrent (14 cases), or metastatic (10 cases) MPNST; 4 primary tumor aspirates were of ex vivo specimens. Sites included the extremities (22 cases), trunk/pelvis (22 cases), head and neck (6 cases), and deep-seated masses (6 cases). FNA diagnoses were MPNST (24 patients); consistent with MPNST (5 patients); sarcoma, not otherwise specified (10 patients); atypical (3 patients); spindle cell neoplasm (6 patients); malignant neoplasm (1 patient); and nondiagnostic (3 patients). A definitive diagnosis of either MPNST or consistent with MPNST was issued in 30%, 93%, and 70%, respectively, of primary, locally recurrent, and metastatic lesions.

CONCLUSIONS

FNA cytopathology is limited as a diagnostic instrument for the initial diagnosis of MPNST, but is exceedingly accurate and valuable in the recognition of metastatic and locally recurrent MPNST.

Fine-needle aspiration cytology of malignant peripheral nerve sheath tumors

The histopathologic features of malignant peripheral nerve sheath tumors (MPNSTs) have been well described. There have been limited studies on the cytologic features of MPNST. In this present study, we have retrospectively reviewed eight histopathology confirmed cases of MPNST over a 5-year period. Detailed cytomorphological analysis of these cases was carried out individually by two observers. On cytology, these cases were diagnosed as benign spindle-cell tumor (two), spindle-cell tumor possibly benign (one), spindle-cell tumor possibly malignant (one), malignant spindle-cell tumor (two), spindle-cell tumor, and neural origin (two). The cardinal cytomorphologic features were loosely cohesive clusters and fascicular arrangement of spindle cells with rounded ends. The kinking of nuclei was not a conspicuous finding. Fibrillary background was noted in two of the cases. Nuclear pleomorphism was ranged from mild to moderate degree. One case exhibited extensive intranuclear pseudoinclusions. Mitotic figures (including atypical forms) were present in almost all the cases. Possibly a constellation of cytologic features such as clusters of short and long fascicles of cells admixed with dissociated spindle cells of round-ended nuclei and prominent nucleoli on myxoid or fibrillary background and frequent mitosis may be helpful in diagnosis of MPNSTs. The cytomorphologic features along with clinical correlation are necessary to increase the diagnostic accuracy of MPNST on aspiration cytology.

Endoscopic ultrasound-guided fine-needle aspiration cytology of peripheral nerve-sheath tumors

Endoscopic ultrasound (EUS) has allowed for the fine-needle aspiration and diagnosis of many different gastrointestinal neoplasms, including mesenchymal tumors. Although most mesenchymal tumors of the gastrointestinal tract are gastrointestinal stromal tumors (GISTs), other mesenchymal tumors, including neural tumors, do occur. Proper diagnosis and differentiation of these tumors from GISTs are important because of their different prognoses and treatment regimens. We encountered three peripheral nerve-sheath tumors of the gastrointestinal tract aspirated by EUS (two schwannomas and a granular-cell tumor). We report on the endoscopic ultrasound, cytologic, histologic, and immunohistochemical findings of these cases.

Cytohistologic correlations of 24 malignant peripheral nerve sheath tumor (MPNST) in 17 patients: the Institut Curie experience

Cytomorphological patterns of malignant peripheral nerve sheath tumor (MPNST) are insufficiently documented in the literature. Cytological and histological specimens in 24 tumors in 17 patients were correlated. The review of the original cytology reports showed that four (16.6%) tumors were correctly diagnosed, eight (33.3%) were diagnosed as sarcoma not otherwise specified, four (16.7%) as fibrosarcoma, three (12.5%) as synovial sarcoma, three (12.5%) as leiomyosarcoma, and one (4.2%) case each as malignant fibrous histiocytoma and rhabdomyosarcoma. At the review tumors were histologically reclassified as well-differentiated MPNST in 11 (45.9%) cases, anaplastic MPNST in 11 (45.9%) cases, and epithelioid MPNST and malignant Triton tumor in one (4.2%) case each. Cytologically, well-differentiated MPNST were composed of polymorphous oval to round cells, small spindle-shaped cells with wavy and comma-like naked nuclei, and a fibrillary, delicate stroma. Anaplastic MPNST, moreover, were composed of anaplastic giant and polymorphous cells. The malignant Triton tumor was composed of oval to round rhabdomyoblastic cells with eccentric nuclei and the epithelioid MPNST of polymorphous and round, epithelial-like cells. The cytological diagnosis of MPNST may be difficult, especially in anaplastic tumors. The correlation between the cytological features and the clinical information--origin of the tumor from a nerve trunk, a preexisting neurofibroma, patients with known history of neurofibromatosis 1--could be indicative of an MPNST diagnosis.

Fine-needle aspiration cytology and core biopsy of malignant peripheral nerve sheath tumor of the uterus: a case report

Malignant peripheral nerve sheath tumor (MPNST) is an uncommon mesenchymal neoplasm of neural origin. MPNST arising in the uterus is extremely rare. Its histologic appearance on this anatomical location has been only rarely reported. A 62-yr-old woman with a previous history of partial hysterectomy presented with a large pelvic mass in the uterine stump. Fine-needle aspiration (FNA) and core biopsy were obtained under ultrasonographic guidance, and the diagnosis of MPNST was established. The cytologic and histologic findings were consistent with a spindle-cell neoplasm suggestive of MPNST. The tumor cells were focally positive for S-100 protein immunostain, thus providing further support for the neoplasm's nerve sheath differentiation. The patient had no history of von Recklinghausen's disease. Resection of the mass confirmed the diagnosis of MPNST. To our knowledge, the FNA cytology of MPNST in this unusual location has not been previously reported. FNA cytology, along with core biopsy and immunochemistry, is a reliable tool in the diagnosis of MPNST.

Fine-needle aspiration of neural lesions

The cytomorphologic features of 13 neural lesions sampled by fine-needle aspiration (FNA) are reviewed. The frequencies at which various architectural features including Verocay bodies, filamentous background, and vascular arcades were present was recorded, along with the frequencies of cytologic findings including the presence of spindle cells, wavy nuclei, intranuclear inclusions, fishhook nuclei, nuclear pleomorphism, filamentous cytoplasm, and mitotic figures. Verocay bodies were a rare finding, present in only 1 of 11 cases. Vascular arcades were similarly infrequent (1/11 cases). Spindle-shaped cells along with wavy nuclei were the most frequent findings, with fishhook-shaped nuclei and a filamentous background of high frequency (9/11 cases). Our study indicates that some of the characteristic features recorded in the literature are rarely seen in needle aspiration smears, but features such as spindle-shaped cells, wavy and fishhook-shaped nuclei, and a filamentous background are relatively frequent findings.

Malignant melanotic schwannoma fine-needle aspiration biopsy findings

We describe the cytologic, histologic, and clinical features of two cases of melanotic schwannoma, arising in the neck and superior mediastinum, respectively. Cytologic findings in both cases included the presence of cells with heavily pigmented cytoplasm, showing long branching projections. The cells were arranged in clusters, with ill-defined boundaries. Histologic findings included interlacing fascicles of cells, with abundant melanin pigment, calcification, and necrosis. Immunohistochemical stains were positive for S. 100 protein and anti-human melanoma (HMB45). Both patients died with metastases.

The cytopathology of synovial sarcoma: a study of six cases, with emphasis on architecture and histopathologic correlation

BACKGROUND

In this article, the architectural and cytologic features of synovial sarcoma are described.

METHODS

Romanowsky- and Papanicolaou-stained fine-needle aspiration smears and corresponding hematoxylin and eosin sections were retrieved from archival material and examined by light microscopy.

RESULTS

Microtissue fragments comprised of spindle cells dominated smears and correlated with fibrosarcoma-like areas prevalent in tissue sections. Characteristic fascicular and whorled patterns were apparent, and matrix material representing collagenous stroma varied from fibrillary to hyalinized. Epithelial components included polygonal and rectangular cells isolated from spindle cells, gland-like formations occurring within otherwise spindle cell microtissue fragments, and clubbed, spindle cell collections lined by flattened epithelial cells.

CONCLUSIONS

Features of synovial sarcoma as defined previously by histopathology were apparent in cytologic preparations, facilitating a primary diagnosis by cytology.

Fine-needle aspiration of epithelioid malignant peripheral nerve sheath tumor (epithelioid malignant schwannoma)

The epithelioid variant of malignant peripheral nerve sheath tumor (MPNST), also known as malignant epithelioid schwannoma, is a relatively rare and recently characterized clinicopathologic entity. The epithelioid variant of MPNST shares many clinical features with conventional MPNST but is characterized by different histologic and cytologic features. These include a distinctive nesting pattern and an abundance of cytoplasm not seen in histology of conventional nerve sheath tumors. Cytologically, the epitheliod variant shows a propensity to cellular discohesiveness and a plasmacytoid or epitheliod appearance that is in contradistinction to the spindled appearance of the usual MPNST. Herein, we report our experience with fine-needle aspiration (FNA) of two epithelioid malignant schwannomas and discuss the FNA cytologic differential diagnosis.

Fine-needle aspiration cytology of sarcoma: retrospective review of diagnostic utility and specificity

Fine-needle aspiration cytology (FNA) is useful because of its low cost, quick turn around time, and low incidence of complications. This study investigates the role FNA plays in the evaluation of sarcoma. We reviewed all the pathologic material from patients with sarcoma or a FNA diagnosis suggestive of sarcoma at the University of California-Davis Medical Center (1985-1994). Fifty-two of 196 patients identified (26.5%) were evaluated with FNA exhibiting 46 soft tissue and 6 bone lesions located in the extremities (19), trunk (19), head and neck (8), retroperitoneum (3), and abdominal cavity (3). Among 196 patients identified, those evaluated by FNA had soft tissue rather than bone lesions (P < .001) and primary sites other than in the extremities (P < .001). The primary neoplasms for the 52 FNA patients included 47 sarcomas (10 malignant fibrous histiocytomas and 16 other types), 1 intramuscular myxoma, 2 lymphomas, and 2 spindle cell (sarcomatoid) carcinomas. In 43 patients (22% of total), FNA was used first, before a primary diagnosis. The FNA report showed the correct specific neoplasm in only 20.9%. However, the FNA reports reflected an effective positive diagnosis leading to appropriate diagnostic biopsy in 88.4%, while only 7.0% were misleading (benign or inflammatory) and 4.6% inadequate. Review of FNA slides for 32 of 43 patients in which FNA was used first, in a blinded fashion, exhibited 21.9% specificity for the specific neoplasm, and 88.4% effective positive diagnoses. In 9 patients, FNA was utilized to investigate recurrence. Five out of 5 instances of recurrent sarcoma were identified by FNA. However, FNA misidentified recurrence in 3/4 instances, exhibiting suspicious cells from regenerating skeletal muscle (2) and a traumatic neuroma (1). The specific diagnosis for sarcomas is challenging even with surgical material. FNA usually does not provide a specific diagnosis (only in 20.9% of cases) and review of routinely prepared slides showed the same specificity as reflected by the original FNA report, at times formulated with the benefit of immunohistochemistry or electron microscopy. FNA effectively evaluated lesions in 45 of 52 patients (86.5%), confirming the useful screening role for this technique in sarcomas.

Radiation induced malignant schwannoma arising in a neurofibroma

Radiation induced sarcomas offer diagnostic and therapeutic challenges. The authors report an unusual case of radiation induced sarcoma arising 9 years after radiation therapy for chordoma. The location of this mass in the retroperitoneum and its intimate involvement with the spine raised difficult management issues. After limited resection was performed, consistent with the intraoperative diagnosis of a benign neurofibroma, foci of malignant transformation were found in areas of the specimen remote from the biopsy site. This complicated management of the sarcoma. The possibility of occult malignancy should be considered when evaluating tumors arising in a previously irradiated field. Thorough sampling at the time of biopsy is required to evaluate such lesions, particularly peripheral nerve sheath tumors.

Diagnosing intramuscular myxoma by fine-needle aspiration: a multidisciplinary approach

The gross and microscopic appearances of aspirates from ten intramuscular myxomas are reported. The specimens were obtained from seven women and three men, ages 43 to 75, who had tumors involving the muscles of the thigh (7), upper arm (2), and forearm (1). Magnetic resonance (MR) imaging performed in six of the ten cases revealed well-defined, sharply demarcated tumors exhibiting low signal intensity relative to muscle on the T1-weighted images. The tumors were hyperintense to muscle on T2-weighted images. All aspirated tissues were clear, tenacious, and viscous. Smears contained few spindled and histiocytoid cells in an abundant mucoid background. Spindle cells demonstrated long cytoplasmic processes that in areas intertwined to form fibrillar tangles. Nuclei were oval to spindled with fine chromatin and inconspicuous nucleoli. Capillaries were sparse with simple (non-plexiform) branching. The differential diagnosis of myxoid lesions of the extremities includes benign entities such as myxoid schwannoma and neurofibroma, mesenchymal repair, and ganglion cyst, as well as malignant neoplasms such as myxoid liposarcoma, fibrosarcoma, malignant fibrous histiocytoma, and extraskeletal chondrosarcoma. The findings of this study revealed that, although the cytologic features were suggestive of intramuscular myxoma, a definitive diagnosis was often difficult, owing to scant cellularity and lack of distinctive cytologic features. The MR imaging findings may be utilized as an adjunct to the cytologic features to more confidently suggest a diagnosis of intramuscular myxoma.

Melanocytic schwannoma: the cytologic aspect in fine-needle aspiration cytology (FNAC): report of a case located in the spinal cord

We describe a case of intramedullary melanocytic schwannoma (MS) studied by means of fine-needle aspiration cytology (FNAC). The main cytologic features were (1) large three-dimensional clusters overshadowed by heavy pigment deposits which tested positive for Fontana Masson (and bleached with potassium permanganate), HMB-45, Vimentin, and S-100 protein; (2) loose syncytial monolayered sheets with very little pigment deposit; and (3) isolated spindle cells with polarized nucleus and tapered, thin cytoplasmic ends. Both the cytologic features and the immunophenotypic profile were nonspecific and on their own were insufficient to allow the diagnosis of MS to be reached. Clinical data and the magnetic resonance image (MRI) in conjunction with the cytologic findings did suggest the diagnosis of intramedullary MS.

Fine-needle aspiration biopsy: pitfalls in the diagnosis of spindle-cell lesions

Seven cases of spindle-cell proliferations in which fine-needle aspiration biopsy (FNAB) did not correlate with subsequent histology are presented. Three cases were considered low-grade sarcoma, one a dermatofibrosarcoma protuberans (DFSP), one a spindle-cell tumor with malignancy not excluded, and one a rhabdomyosarcoma vs. a fibrosarcoma. Two of the these three were histologically nodular fasciitis and one an inflammatory pseudotumor. Two cases were diagnosed cytologically as fibromatosis or nodular fasciitis (NF). One of these histologically was an intramuscular hemangioma, the other a DFSP. The last two cases were diagnosed by FNAB as spindle-cell lesion, undetermined if benign or malignant, and malignant fibrous histiocytoma (MFH). Histologically both of these case were leiomyosarcoma. The cytologic features of each case, differential diagnosis, and potential pitfalls are discussed. In the evaluation of FNAB smears dominated by spindle cells, cellullarity, individual cells and cell patterns, and background stromal features coupled with a precise clinical history may allow a narrow differential diagnosis with a focus on whether the lesion is benign or malignant. Caution is warranted in the exact classification of spindle-cell tumors from FNAB as this may have a major impact on patient management.