Sarcoma with MGA::NUTM1 fusion: a report of three cases and literature review.

AIMS: NUTM1-rearranged sarcoma is an emerging entity that differs from NUT carcinoma at the molecular level, with most of the former tumours harbouring fusions involving genes in the MYC-associated factor X dimerization (MAD) transcription family (MXD1, MXD4, MXI1 [or MXD2], and MGA). MGA::NUTM1 is one of the most recently described novel gene fusions associated with NUTM1-rearranged sarcoma. Herein we describe the clinicopathologic features of three sarcomas with an MGA::NUTM1 fusion. METHODS AND RESULTS: The three study patients were male, with an age range of 10-28 years. The tumour sites were deep soft tissue of the thigh, the chest wall, and the pelvis. All three tumours were aggressive, with multiple recurrences and metastases. Histologically, the tumours were composed of monotonous spindle, round, or epithelioid cells in variably hyalinized stroma and prominent aggregates of amianthoid fibre-like collagen or collagen rosettes. Mitotic activity was relatively low (5-12 mitotic figures per 10 hhpf). All tumours tested expressed NUT, with one tumour having S100 protein expression and two tumours having CD99 and CD56 expression. The genetic breakpoints were MGA exon 21, MGA exon 22, and NUTM1 exon 3. CONCLUSION: MGA::NUTM1 sarcoma often exhibits hyalinized stroma with amianthoid fibre-like collagen or collagen rosettes in the presence of monotonous round, epithelioid, or spindle cell morphology. NUT immunohistochemistry and molecular testing can help confirm the diagnosis.

Atypical spindle cell/pleomorphic lipomatous tumour (ASPLT): A report of three FNA cases and comparison with spindle cell/pleomorphic lipoma cytopathology.

INTRODUCTION: Atypical spindle cell/pleomorphic lipomatous tumour (ASPLT) is an infrequently appreciated benign lipomatous neoplasm newly accepted into the most recent WHO classification of soft tissue tumours. MATERIALS AND METHODS: Our cytopathology files were searched for examples of ASPLT and spindle cell/pleomorphic lipoma (SCPL) having histopathological verification. Conventional fine needle aspiration (FNA) biopsy smears were performed using standard techniques. RESULTS: Eleven patients including three cases of ASPLT and eight of SCPL (M:F = 4.5:1; age range: 39-97 years, mean age = 60 years) met the inclusion criteria. FNA biopsy sites included extremity (5, 45%), trunk (3, 27%), and head/neck (3, 27%). All aspirates were from primary neoplasms. FNA diagnoses of ASPLT cases were spindle cell lipomatous neoplasm, fibrotic low-grade SC neoplasm, and myxoid lipomatous neoplasm. Eight SCPL cases were diagnosed as spindle cell neoplasm (3), spindle cell lipoma (SCL) (1), pleomorphic lipoma (1), suspicious for SCL (1), benign adipose tissue (1), and benign spindle cells and connective tissue (1). Ancillary testing in two ASPLT cases showed positive CD34 and negative MDM2 immunostain in one, and negative FISH results for MDM2 and DDIT3 in another. CONCLUSION: ASPLT is a novel lipomatous neoplasm simulating primarily SCPL and atypical lipoma/well-differentiated liposarcoma. Diligent cytomorphological observation, clinical information, and ancillary testing may allow for its specific recognition using FNA biopsy.

Haemoglobin spherulosis: Fine needle aspiration biopsy of an unusual ocular lesion.

OBJECTIVE: Haemoglobin spherulosis (HS) is a rare lesion occurring post-vitreous haemorrhage that is absent from the cytopathology literature. METHODS: We present the fine needle aspiration (FNA) biopsy cytological features of a case of HS occurring in a 73-year-old woman. RESULTS: FNA smears of hemorrhagic vitreous fluid showed numerous variably sized smooth glassy spherules ranging from 3-20 µm. Occasional red cells and a rare lymphocyte were observed, but other cell types were absent. Immunohistochemical staining of a cell block showed diffuse positive staining of spherules with haemoglobin A. CONCLUSIONS: HS is a rare lesion that occurs post-subretinal haemorrhage and may be encountered by pathologists examining ocular cytological specimens.

Cytopathology of benign sebaceous salivary gland neoplasia: Comparison of two analogous yet dissimilar entities.

INTRODUCTION: Benign sebaceous salivary gland (SG) neoplasms represent approximately 0.2% of all salivary gland neoplasms. Not only are fine needle aspiration (FNA) biopsy findings of sebaceous adenoma (SA) and sebaceous lymphadenoma (SLA) limited, but their findings are also rarely compared with one another. MATERIALS AND METHODS: Our cytopathology files were searched for examples of benign sebaceous SG neoplasms with concomitant histopathological verification. FNA biopsy and cell collection were performed using standard technique. RESULTS: One case each of parotid SA and parotid SLA showed markedly dissimilar cytomorphology. The SA case was composed of a repetitive population of profusely multivacuolated polygonal cells with single and multiple nuclei, and was specifically recognised cytologically as a sebaceous neoplasm due to its characteristic cytoplasmic vacuolisation. The SLA case, however, was characterised by smears filled primarily with lymphocytes and only scant widely scattered basaloid cell clusters. A non-specific diagnosis of basaloid neoplasm was rendered. In retrospect, recognition of sebaceous differentiation was limited to rare cell groups. CONCLUSION: Though nominally, epidemiologically, and to a degree histopathologically analogous, the cytopathology of SA and SLA are markedly dissimilar, reflecting the dominant cell component in each. With FNA biopsy, a specific interpretation is more likely for SA than SLA due to the overwhelming obscuring lymphoid population in the latter.

Fine needle aspiration cytopathology of pleomorphic dermal sarcoma.

INTRODUCTION: Pleomorphic dermal sarcoma (PDS) is an uncommon cutaneous mesenchymal neoplasm. It is cytomorphologically identical to atypical fibroxanthoma (AFX), but differs due to its invasion beyond the dermis. We undertook an examination of our experience with fine needle aspiration (FNA) biopsy cytology of PDS. MATERIALS AND METHODS: Our cytopathology files were searched for examples of PDS with concomitant histopathological verification. FNA biopsy smears and cell collection were performed using standard techniques. RESULTS: Seven cases of PDS were retrieved from four different patients (M:F, 1:1; age range: 63-88 years; mean age = 78 years). All patients (57%) presented with a primary tumour with one having an FNA biopsy of two local recurrences and a single distant metastasis. Five aspirates were from the extremities and two from the head/neck. Tumours ranged from 1.0 to 3.5 cm (mean, 2.2 cm). Specific cytological diagnoses were pleomorphic spindle/epithelioid sarcoma (3 cases), PDS (2), AFX (1), and atypical myofibroblastic lesion, query nodular fasciitis (1). Immunohistochemical (IHC) staining from FNA-generated cell blocks in two cases showed non-specific staining with vimentin in both cases; positive CD10, CD68, and INI-1 staining in one case; and smooth muscle actin expression in the other. Multiple negative stains were performed in both of these cases to exclude malignant melanoma, carcinoma, and specific forms of sarcoma. Cytopathology consisted of a mixture of spindle, epithelioid, and bizarre pleomorphic cells. CONCLUSION: Coupled with ancillary IHC stains, FNA biopsy can help recognise PDS as a sarcomatous cutaneous neoplasm, but is unable to distinguish PDS from AFX.

Approach to FNA of Myxoid Soft Tissue Tumors.

Myxoid tumors of the soft tissue encompass a group of heterogenous tumors that are characterized by the presence of abundant extracellular myxoid or chondromyxoid matrix material. Fine needle aspiration (FNA) is variably used for diagnosing primary, recurrent, and metastatic myxoid soft tissue tumors. The spectrum of myxoid soft tissue tumors encountered in practice ranges from benign lesions such as simple ganglion cysts to high-grade malignant sarcomas such as myxofibrosarcoma. These myxoid tumors have clinical, cytologic, and histologic overlap. Therefore, making an accurate diagnosis by FNA alone is challenging. Despite this challenge, using a systematic cytomorphologic approach and ancillary studies, an accurate diagnosis is feasible in the majority of cases. This article provides a systematic approach to diagnosing myxoid soft tissue tumors by FNA along with a review of the literature.

Classic polymorphous adenocarcinoma: Fine needle aspiration cytopathology of eight cases.

INTRODUCTION: The cytopathology and diagnostic accuracy of salivary gland (SG) polymorphous adenocarcinoma (PAC) is the subject of a limited number of reports. We undertook a review of our experience with fine needle aspiration (FNA) biopsy and PAC. MATERIALS AND METHODS: A search was made of our cytopathology files for PAC cases that also had histopathological confirmation. FNA biopsy smears and cell-blocks were performed and examined using standard techniques. RESULTS: Eight FNA biopsy cases of histologically proven PAC from 7 patients [F:M = 1.3:1, age 39-75 years, mean = 58] met study inclusion. Metastatic aspirates were most common (4), followed by 3 primary cases and 1 locally recurrent neoplasm. Primary FNA sites included hard palate (1 case), lip (1), and lateral tongue (1); all metastatic sites were in the neck. A precise cytologic diagnosis was made in 38% of cases; however, when applying the Milan classification system, 100% could be categorised as either malignant or of uncertain malignant potential. Ancillary immunohistochemical testing performed in 44% of the cases was non-specific. Cytologic smears showed cellular uniformity and structural variety of cell groups with tubular, branching, cribriform, and convex patterns as well as variable, but occasionally abundant globular myxoid stroma leading to confusion with adenoid cystic carcinoma. CONCLUSION: The imitative cytopathology of PAC with other SG neoplasms as well as its infrequency in routine FNA biopsy practice makes specific interpretation difficult, but using a classification system allows for appropriate patient management. Molecular testing in future specimens holds promise for enhancing diagnostic accuracy.

Activity of PD1 inhibitor therapy in advanced sarcoma: a single-center retrospective analysis.

BACKGROUND: Sarcomas constitute a heterogeneous group of tumors with different clinical behaviors and variable responses to systemic therapies. Recent immunotherapy studies with PD1 inhibitors (PD1i) show promising results with use in certain soft-tissue sarcomas; however, the clinical and molecular features that best predict response to PD1i remain unclear. METHODS: Demographic, imaging, histologic, and genetic sequencing data was collected for sarcoma patients who received nivolumab or pembrolizumab (PD1i) treatment at our institution between January 1st 2015 and April 23rd 2018. The primary objective was to determine progression-free survival (PFS) in patients with advanced sarcomas receiving PD1i. Secondary objectives included determining overall survival (OS) and assessment of characteristics associated with response to PD1i. Fifty-six patients who were treated with PD1i therapy met inclusion criteria for this study. RESULTS: Partial response towards PD1i treatment was seen in 3 in 26 evaluable patients, but no complete responses were observed (overall response rate 11.5%). Within this group of patients, the 90 day PFS was found to be 48.8%. In patients in whom PD1 expression was known, there was a statistically significant positive correlation between expression of PD1 and longer PFS and OS rates. Patients that were treated with more than four cycles of PD1i therapy were also more likely to have a greater OS. CONCLUSIONS: This study suggests activity of PD1i in a pretreated cohort of advanced sarcoma patients, particularly for the subset of patients with PD1 positive tumors. Our results highlight the importance of further research to better target the optimal patient population and markers of response.

Degree of MDM2 Amplification Affects Clinical Outcomes in Dedifferentiated Liposarcoma.

BACKGROUND: Dedifferentiated liposarcomas (DDLPS) are mesenchymal tumors associated with universally poor response to treatment. Genomic amplification of murine double minute 2 (MDM2) is used as a diagnostic biomarker; however, no established biomarkers exist to guide DDLPS treatment. In the largest study of its kind, we report that the extent of MDM2 amplification, not simply the presence of MDM2 amplification, may be biologically important to the actions of DDLPS. PATIENTS AND METHODS: The distribution of MDM2 amplification in DDLPS was assessed using data from a commercial sequencing laboratory (n = 642) and The Cancer Genome Atlas (n = 57). Data from two retrospective clinical trials (n = 15, n = 16) and one prospective clinical trial (n = 25) were used to test MDM2's utility as a clinical biomarker. in vitro and in vivo assessments were conducted in DDLPS cell lines. RESULTS: Genomic MDM2 amplification follows a highly reproducible log-normal distribution. In patients with DDLPS treated with complete tumor resection, elevated MDM2 was associated with shortened time to recurrence as measured by genomic amplification (p = .003) and mRNA expression (p = .04). In patients requiring systemic therapy, higher MDM2 amplification was associated with reduced overall survival (p = .04). Doxorubicin treatment of DDLPS cells in vitro demonstrated variable sensitivity based on baseline MDM2 levels, and doxorubicin treatment elevated MDM2 expression. In vivo, treatment with doxorubicin followed by an MDM2 inhibitor improved doxorubicin sensitivity. CONCLUSION: MDM2 amplification levels in DDLPS follow a reproducible distribution and are associated with clinical outcomes and drug sensitivity. These results suggest that a prospective study of MDM2 as a predictive biomarker in DDLPS is warranted. IMPLICATIONS FOR PRACTICE: No validated biomarkers exist for treatment selection in dedifferentiated liposarcoma (DDLPS). Although murine double minute 2 (MDM2) is currently used for diagnosis, the clinical relevance of MDM2 amplification has yet to be fully assessed. This study found that MDM2 amplification follows a predictable distribution in DDLPS and correlates with clinical and biological outcomes. These data suggests that MDM2 amplification may be a useful biomarker in DDLPS.

Diagnostic traps awaiting the head/neck pathologist: "Cytoplasm-poor" neoplasms.

CONTEXT: Beyond squamous carcinoma, a variety of diagnostically challenging neoplasms arise within various head and neck sites. This is particularly the situation with neoplasms where little cellular cytoplasm is present to assist the pathologist in categorizing such lesions. OBJECTIVE: To highlight diagnostic pitfalls that accompanying neoplasms composed primarily of 'cytoplasmically-poor' cells. These pitfalls include morphologic and immunohistochemical traps that emerge from this class of neoplasms. DATA SOURCES: Selection of pathologic specimens from the author's personal files, and literature review. CONCLUSIONS: Interpretative pitfalls regarding the histopathology and immunophenotype of small 'cytoplasmically-poor' neoplasms are a diagnostic hazard in head and neck surgical pathology practice, and require knowledge of histomorphologic plasticity and aberrant immunophenotyping.

Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma of bone: Clinicopathologic features of 5 cases.

Pseudomyogenic hemangioendothelioma (PHE) is an uncommon mesenchymal tumor of intermediate malignant potential with characteristic clinicopathologic and genetic features. Although bone involvement accompanies nearly one-fourth of reported cases of soft tissue PHEs, primary intraosseous PHE is rare. Herein, we report five cases of primary intraosseous PHEs. Male to female ratio was 4:1, with an average age of 28 years (age range, 5-44 years). Radiologically, tumors presented as lytic lesions in the proximal femur (two), diaphysis of the tibia (one), distal radius (one) and vertebrae (one). Multifocal lesions were observed in four cases. Histopathologic examination revealed plump spindle cells and prominent nucleoli. New bone formation was noted in three cases. Immunohistochemically, all tumors were positive for CD31 and negative for CD34. Pan Cytokeratin (CK) (AE1/3) was positively expressed in all, except a single tumor, in which CK7 and Cam5.2 were expressed. INI1/SMARCB1 was completely retained in all tumors. A single patient underwent surgical resection. During follow-up, two cases showed no evidence of disease within two and five years, respectively. Differential diagnosis of a PHE of bone includes osteoblastoma, epithelioid angiosarcoma, metastatic carcinoma, metastatic rhabdomyosarcoma, and epithelioid sarcoma. Caution must be exercised as pan CK (AE1/3) might not be expressed; therefore, the use of other cytokeratins, such as Cam5.2 is recommended. Awareness of such an entity in bone is the key to the diagnosis.

Undifferentiated (anaplastic) thyroid carcinoma: Practical immunohistochemistry and cytologic look-alikes.

Aspirate smears of undifferentiated (anaplastic) thyroid carcinoma (ATC) are, in most instances, readily recognized as malignant. Nonetheless, pitfalls exist with this neoplasm in part due to the absence of epithelial markers, overlapping features with other malignancies that may metastasize to or arise within the thyroid, and potential confusion with non-neoplastic conditions that simulate malignancy. We highlight the salient morphologic features of ATC and its variants, useful discriminatory ancillary immunostains to recognize it, and ATC mimickers that have the potential to confuse the cytopathologist.

Primary gastric extra-uterine endometrial stromal sarcoma.

Endometrial stromal sarcoma (ESS) is an uncommon uterine neoplasm, but its occurrence as an extra-uterine primary (EESS) is exceedingly unusual, and the fine-needle aspiration (FNA) cytopathology of EESS is rarely described. We hereby present 2 women with primary gastric EESS whereby the FNA cytopathology of this rare entity showed a population of cytologically monotonous oval-spindle shaped cells. This cytopathology is correlated with the subsequent histopathology. EESS is another, albeit rare, diagnostic consideration along with gastrointestinal stromal tumor, schwannoma, glomus tumor, and leiomyoma of cytologically bland neoplasms of the stomach that can be encountered using endoscopic ultrasound-guided FNA biopsy.

Sino-orbital spelunking: stalagmite formation in fibrous dysplasia with dystrophic calcification.

Fibrous dysplasia (FD) involving the mid-face may be associated with cystic and other secondary changes that make diagnosis more difficult. We present a case of FD associated with a remote history of blunt facial trauma and extensive cystic changes involving the medial orbit and sinuses. An endoscopic exploration revealed "stalagmites" along the floor of the cystic cavity that were consistent with dystrophic calcification. This case was unusual given the degree of dystrophic calcification and the presence of sino-orbital stalagmites within the cystic cavity. Radiologic and pathologic features of the stalagmites are characterized.

Fungal Otitis Externa (Otomycosis) Associated with Aspergillus Flavus: A Case Image.

A 48-year-old man presented with a chief complaint of intermittent right ear otorrhea of several-month duration, occasional otalgia and progressive unilateral hearing impairment. He also reported frequent episodes of headache and pressure in the sinuses and maxilla. Previous systemic treatment with antibiotics failed to alleviate the symptoms. A head/neck CT showed completely normal mastoid, middle ear and external auditory canal regions without any evidence of opacification or bone erosion. Otoscopic examination of the right ear disclosed aggregates of dried, brown, fibrillar material and debris occluding the external auditory canal and obstructing the otherwise intact tympanic membrane. Dilation of the external auditory canal or thickening of the tympanic membrane were not appreciated. The canal was debrided and the fibrillar material was placed in formalin. Histopathologic examination revealed numerous branching, septated fungal hyphae organized in densely-packed clusters. In other areas, the fungal hyphae abutted or were attached to lamellated collections of orthokeratin. As highlighted by GMS staining, the fungi were morphologically compatible with Aspergillus species. The clinicopathologic findings supported a diagnosis of fungal otitis externa, while the numerous anucleate squamous cells were compatible with colonization of an underlying, probably developing, cholesteatoma. Culture of material isolated from the external auditory canal confirmed the presence of Aspergillus flavus. In this illustrative case, we present the main clinical and microscopic characteristics of Aspergillus-related otomycosis developing in the setting of a tautochronous cholesteatoma.

SMARCB1-Deficient Skull Base Chondrosarcoma with 12p Duplication Presenting as Somatic-Type Malignancy Arising from Metastatic Seminoma.

Somatic-type malignancy (STM) can occur infrequently within a primary or metastatic testicular germ cell tumor (TGCT) and is associated with dismal prognosis and survival. STM with chondrosarcomatous features is exceedingly rare and head and neck involvement has not been previously documented. A 39-year-old white man presented with nasal obstruction and epistaxis. Imaging disclosed a 6.9-cm expansile tumor involving the nasal cavity and skull base with intraorbital and intracranial extension. The histopathologic properties of the tumor were compatible with chondrosarcoma, grade II-III. Immunohistochemically, malignant cells were strongly and diffusely positive for S100 and epithelial markers, and showed loss of SMARCB1 expression. IDH1/2 mutations were not detected. Following whole-body PET scan, a 7.0-cm left testicular mass was discovered and diagnosed as seminoma with syncytiotrophoblastic cells, stage pT3NXM1b. Extensive retroperitoneal, mediastinal, and supraclavicular lymphadenopathy was also noticed. Histopathologic examination of the left supraclavicular lymph node revealed metastatic seminoma. By FISH, most metastatic nodal seminoma cells harbored 1 to 4 copies of isochromosome 12p, while the chondrosarcoma featured duplication of 12p. Presence of a malignant TGCT with disseminated supradiaphragmatic lymphadenopathy, the unique immunophenotypic properties of the skull-based chondrosarcoma and lack of IDH1/2 aberrations with gain of 12p strongly support the diagnosis of STM chondrosarcoma arising from metastatic TGCT. The patient did not respond to chemotherapy and succumbed three months after diagnosis. Although exceedingly uncommon, metastasis to the head and neck may occur in patients with TGCT. This case of STM chondrosarcoma demonstrated divergent immunophenotypic and molecular characteristics compared to "typical" examples of head and neck chondrosarcoma. High index of suspicion is advised regarding the diagnosis of lesions that present with otherwise typical histomorphology but unexpected immunohistochemical or molecular features.

Acral myxoinflammatory fibroblastic sarcoma: cytopathologic findings on fine-needle aspiration.

BACKGROUND: Acral myxoinflammatory fibroblastic sarcoma (AMFS) is a rare low-grade sarcoma with somewhat unique morphologic characteristics. While recurrences are relatively common, distant metastases are infrequent. Cytopathologic descriptions of AMFS are limited, prompting the current study. METHODS: A retrospective review was performed at two tertiary-care hospitals, and 3 patients with this diagnosis were identified. The cytopathologic and clinical features were reviewed. The following clinical data was collected for each case: age, gender, site of lesion, treatment, and follow-up information. RESULTS: Pertinent cytologic features included large atypical epithelioid cells with occasional macronucleoli and lipoblast-like features in a background of bland spindle cells, myxoid stroma, and inflammation. All patients presented with acral mass lesions. Metastatic disease to an inguinal lymph node was found in 1 patient. CONCLUSIONS: AMFS is a low-grade sarcoma which shows some characteristic cytologic features. However, due to the presence of occasional bizarre and pleomorphic giant cells, there can be overlap with higher-grade sarcomas, and correlation with histology, immunohistochemistry, and imaging are required to make this diagnosis.

Metastases to the pancreas diagnosed by fine-needle aspiration.

BACKGROUND: Metastatic cancer infrequently involves the pancreas. When the pancreas hosts a metastatic tumor, cytopathological evaluation of fine-needle aspirate material is a crucial part of the diagnostic process. In this study, we show two institutions' experience with cytopathological diagnosis of pancreatic metastasis. METHODS: Databases of institutional experience at The Johns Hopkins Hospital and Ohio State University Medical Center were queried for cases of metastatic tumors in the pancreas that underwent fine-needle aspiration. Demographic and pathological features were compiled and the cytomorphology was reviewed. RESULTS: Forty-two cases of tumor metastasis to the pancreas were found. Over the time of this review, 5,495 aspirates were performed, and 43% (2,389/5,495) had malignant cytological findings. Thus, the 42 cases of metastatic disease to the pancreas comprised 0.8% of all pancreas aspirates and 1.8% of the malignant ones. Renal cell carcinoma was the most common metastasis, followed by melanoma and non-small cell lung carcinoma. Among the other tumors in this series, 2 cases each of rare metastases such as the fibrolamellar variant of hepatocellular carcinoma and solitary fibrous tumor were also seen. CONCLUSION: The pancreas is rarely involved with metastatic disease, but when it is involved the most common tumor is renal cell carcinoma followed by melanoma and non-small cell lung cancer. Clinical history and awareness of the primary pancreatic mimickers are necessary for arriving at the correct diagnosis. As conventional pancreatic adenocarcinoma is uncommon in children and young adults, history of other tumors - even ones that usually follow an indolent course - is essential.

CD31 expression in plasmacytic/plasmablastic lesions.

Although CD31 has been considered one of the better, if not the best, immunohistochemical marker of endothelial cells and thereby vascular neoplasia, it is not unequivocally specific to this group of tumors. We examined CD31 staining in 34 plasmacytic lesions including 15 plasma cell myelomas, 1 extraosseous plasmacytoma, 10 plasmablastic variants of myeloma, 5 plasmablastic non-Hodgkin lymphomas, and 3 reactive plasmacytic infiltrates. All reactive plasma cellular infiltrates, 93% of plasma cell myelomas, 80% of plasmablastic variants of myelomas, and 20% of plasmablastic non-Hodgkin lymphoma cases were CD31 positive with usually diffuse and strong membranous staining. When ERG staining was performed, none were ERG positive. Plasmablastic variant of myeloma is another large cell malignancy that has the potential to be mistaken for a poorly differentiated epithelioid vascular neoplasm if CD31 is presumed to be an explicit marker of endothelial cells.

Benign peripheral nerve tumors: Analysis of 89 FNA cases emphasizing diagnostic accuracy and their morphologic spectrum.

INTRODUCTION: Benign peripheral nerve tumors (BPNTs) are a heterogenous group of soft tissue tumors that include a variety of nerve sheath tumors, granular cell tumor (GCT), and ganglioneuroma. Only a few large studies exist on cytopathology and diagnostic accuracy using fine-needle aspiration (FNA) biopsy for this set of neoplasms. MATERIALS AND METHODS: Both surgical and cytopathology files were searched for cases of BPNT. FNA biopsy was performed using standard techniques. RESULTS: Eighty-nine cases from 88 patients (male:female = 1:1; age range: 16-85 years, mean age, 51 years) met inclusion criteria. FNA sites included extremities (58, 65%), head/neck (14, 16%), deep (9, 10%), and trunk (8, 10%). Aspirates were from primary neoplasms in all but one instance. There were 65 schwannomas, seven neurofibromas, seven perineuriomas, seven GCTs, and three ganglioneuromas/neuromas. Aspirates of schwannoma, GCT, neurofibroma (NF), and perineurioma (PN) were correctly diagnosed in 86%, 100%, 29%, and 0% of cases, respectively. Five tumors (6%) were interpreted as either a specific sarcoma or suspicious for sarcoma. Remaining aspirates were classified as spindle cell neoplasm, salivary gland neoplasm, and nondiagnostic. Cytologic features for schwannoma, NF, PN, and ganglioneuroma showed spindle cell-dominant smears arranged mainly in syncytial clusters. GCT aspirates contained a population of epithelioid cells harboring coarsely granular cytoplasm and bare nuclei. Immunohistochemical (IHC) staining in 55 (62%) cases showed S-100 expression in 95%. CONCLUSION: FNA biopsy coupled with IHC is reliable in correctly classifying schwannoma and GCT, but less so for NF. Perineurioma can be mistaken for sarcoma.