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.     

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. Diagn. Cytopathol. 1997;17:200–204. © 1997 Wiley-Liss, Inc.     

Fine‐needle aspiration cytology of epithelioid malignant peripheral nerve sheath tumor: A case report and review of the literature

The epithelioid variant of malignant peripheral nerve sheath tumor (eMPNST) is an extremely rare soft tissue neoplasm comprising less than 5% of all MPNSTs. It is distinguished cytomorphologically from a conventional MPNST by the presence of polymorphous round epithelioid cells arranged in loose clusters with or without spindled tumor cells. These features pose a diagnostic challenge because the differential diagnosis involves a variety of mesenchymal and non‐mesenchymal tumors including epithelioid sarcoma, sclerosing epithelioid fibrosarcoma, malignant rhabdoid tumor, chordoma, metastatic carcinomas, and melanoma. Thus, it may become imperative to perform immunochemical stains on cell blocks of FNA aspirates to arrive at definitive diagnosis. Reports describing the cytologic features of eMPNST are rare. Herein, we report a case of eMPNST with focus on cytomorphologic and cytoimmunochemical features and differential diagnosis. Diagn. Cytopathol. 2016;44:226–231. © 2015 Wiley Periodicals, Inc.     

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 of chondromyxoid fibroma: a case report

The cytologic presentation of a case of chondromyxoid fibroma studied by fine-needle aspiration in a 17-yr-old black male is described. The cytologic features of chondromyxoid fibroma are presented, and the differential diagnosis of intraosseous cartilaginous neoplasms is reviewed, emphasizing the cytomorphologic differentiation of chondromyxoid fibroma from chondrosarcoma, enchondroma, and chondroblastoma.     

Malignant transformation of neurofibromatosis-1 into low-grade malignant peripheral nerve sheath tumor: a case report

Malignant Peripheral Nerve Sheath Tumor (MPNST) is a malignant mesenchymal tumor. The majority of MPNSTs are found in patients with neurofibromatosis type 1 (NF-1) who have a high-grade sarcoma. At the moment, there are just a few instances of low-grade MPNST caused by NF-1. We present a case of malignant transformation of NF-1 into low-grade MPNST in a patient with a long history of the disease. Multiple protruding masses with ulceration on the right shoulder and chest wall were discovered during physical examination. Complete tumor excision was done, followed by hematoxylin-eosin and immunohistochemical staining. A portion of the tumor had higher cellularity, hyperchromatic cell nuclei, and mitoses were seen in only five out of ten high-power fields. S-100 and vimentin were positive, whereas cytokeratin, desmin, SMA, and CD34 were negative. Ki-67 (MIB1) labeling index hot-spotting was around 25%. This was thought to be NF-1 malignant transformation into low-grade MPNST. Overall, knowing the clinical and pathologic characteristics of the disease, plus growing knowledge or experience with the condition, may improve preoperative diagnostic accuracy and extending survival time.     

Liposarcomatous differentiation in malignant peripheral nerve sheath tumor: A case report

A 63-year-old man was admitted at the emergency department in an acute confusional state, and a computerized tomography scan (CT) revealed hydrocephalus. Despite the rapid introduction of a ventriculo-peritoneal shunt, the patient died soon thereafter. At the post-mortem examination, a large solid mass was found to be firmly attached to a nerve root at the L1–L2 level. Microscopically, the tumor showed the classical features of a malignant peripheral nerve sheath tumor (MPNST) with rhabdomyoblastic differentiation. In addition, there were randomly distributed lobules of well-differentiated adipose tissue with unequivocal atypical nuclei. The diagnosis of MPNST with rhabdomyoblastic and lipoblastic differentiation was made. We are not aware of previously reported lipoblastic differentiation in MPNST. Herein, we present details of the case.     

Fine-needle aspiration cytology of malignant retroperitoneal paraganglioma

The cytologic findings in a fine-needle aspiration sample are described from a large retroperitoneal mass in a 56-yr-old male. The aspiration was performed under CT guidance using a 22-gauge needle, maintaining negative pressure. For cytologic study, on-site smears were prepared and stained by the Papanicolaou method. Additionally, cytospin, filter preparations, cell blocks from the aspirate, histology, and electron microscopy of the tumor tissue were performed. Also, immunodiagnostic staining for neuron-specific enolase (NSE), chromogranin, S-100 protein, vimentin, HMB45, cytokeratin, and Grimelius preparation was performed on cytologic and histologic material. The cytologic material was characterized by cords, suggestive acinar structures, and small follicle-like clusters of cells, while cell blocks from the aspirate showed oval or spindle-shaped nuclei with a somewhat fasciculated appearance. However, sections from the tumor tissue showed an organoid “zellballen” pattern. The nuclei were round, oval, spindly, and epithelioid, with moderate to scanty cytoplasm, smooth nuclear membranes, fine, evenly dispersed chromatin, slight hyperchromasia, and mild pleomorphism. No intranuclear vacuoles were seen. Positive immunohistochemical staining for NSE, chromogranin, and Grimelius preparation was noted in the tumor cells, while staining for vimentin, HMB45, and cytokeratin was negative. Electron microscopy of the tumor tissue revealed the presence of variable numbers of round, membrane-bound, electron-dense neurosecretory granules. The cytohistologic and ultrastructural findings are presented, as well as the results of immunodiagnostic staining which helped in the diagnosis of retroperitoneal paraganglioma, an infrequently reported tumor. Diagn. Cytopathol. 1998;18:287–290. © 1998 Wiley-Liss, Inc.     

Fine-needle aspiration cytology of giant cell tumor of tendon sheath

Giant cell tumor of tendon sheath (GCTTS) is a unique soft tissue lesion of the hands and feet. As the cytomorphological features of this lesion are rarely documented, the spectrum of cytomorphological features in 20 cases of GCTTS seen in fine-needle aspiration (FNA) smears are presented. Patients were in the 12-64-yr age group with an equal sex ratio. Fingers or thumb were the commonest site (16 cases), followed by foot (3 cases) and palm (1 case). FNA smears were cellular and composed of varying proportions of stromal and giant cells. Stromal cells showed a dispersed arrangement and were polygonal to spindle shaped. Nuclear grooves and convolutions were found in some of the stromal cells in all cases. Intranuclear cytoplasmic inclusions were occasionally seen. Polygonal cells with round nuclei and nucleoli having abundant cytoplasm, along with binucleate forms, were also found in all cases. Histological sections were available in 10 cases and corroborated the cytological features. Hemosiderin-laden macrophages (11 of 20 cases) and abundant foamy vacuolation of stromal cells (3 of 20 cases) were also observed in FNA smears. In tissue sections, both features were seen in all cases, but with a patchy distribution. The cytological features of GCTTS are uniform, and FNA cytodiagnosis is possible.     

Malignant peripheral nerve sheath tumor with perineurial cell differentiation (malignant perineurioma)

A unique case of malignant peripheral nerve sheath tumor (MPNST) with perineurial cell differentiation occurring in a 63-year-old woman in a subcutis of the forearm is described. The tumor contained cellular and myxoid areas. The neoplastic cells were fusiform with distinct cell borders. They were arranged in storiform pattern and in wavy parallel cell cords in the cellular areas. Focally, a pleomorphism and mitotic activity (including atypical mitoses) similar to those of malignant fibrous histiocytoma were seen. The myxoid parts contained haphazardly oriented cells and scarce lipoblast-like multivacuolated cells mimicking a liposarcoma. In the differential diagnosis, myxoid liposarcoma, dermatofibrosarcoma protuberans, malignant fibrous histiocytoma and low-grade fibromyxoid sarcoma were considered. Immunohistochemically, perineurial differentiation was indicated by the diffuse expression of epithelial membrane antigen and focal reactivity for CD34. The tumor was negative with antibodies to S-100 protein, Leu-7, CD68 (KP1), vimentin and cytokeratin AE1/AE3. Ultrastructure of tumor cells revealed features of MPNST. No recurrence occurred in the patient during 2 years follow up.     

Nestin expression as a new marker in malignant peripheral nerve sheath tumors

Malignant peripheral nerve sheath tumor (MPNST) can be difficult to diagnose because it lacks specific immunohistochemical markers. S-100, which is a useful marker of MPNST, has limited diagnostic utility. Recent studies suggest that nestin, which is an intermediate filament protein, is expressed in neuroectodermal stem cells. The diagnostic utility of immunostains for nestin and three other neural markers (S-100, CD56 and protein gene product 9.5 (PGP 9.5)) were evaluated in 35 cases of MPNST and in other spindle cell tumors. All MPNST cases were strongly positive for nestin and had cytoplasmic staining. Stains for S-100, CD56, and PGP 9.5 were positive in fewer cases (17/35, 11/35, and 29/35 cases, respectively), and had less extensive staining. Nestin was negative in 10/10 leiomyomas, and weak nestin expression was seen in 10/10 schwannomas, 3/10 neurofibromas, 2/8 synovial sarcomas, 2/10 liposarcomas, 4/7 carcinosarcomas and 3/7 malignant fibrous histiocytomas. In contrast, strong nestin positivity was seen in 10/10 rhabdomyosarcomas, 15/19 leiomyosarcomas, and 9/9 desmoplastic melanomas. Nestin is more sensitive for MPNST than other neural markers and immunostains for nestin in combination with other markers could be useful in the diagnosis of MPNST.     

Epithelioid malignant peripheral nerve sheath tumor of the uterine corpus

Epithelioid variant of a malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma. Rarer still is its occurrence at uncommon sites like the uterine corpus where an index of suspicion for this diagnosis is extremely low. Herein, we report a rare case of a uterine epithelioid MPNST in a young girl who underwent a total abdominal hysterectomy for a uterine tumor that was initially diagnosed as an undifferentiated sarcoma and whose paraffin blocks were submitted to us for review. Biopsy sections showed a malignant tumor, predominantly composed of polygonal cells, including “rhabdoid” forms with conspicuous mitoses. On immunohistochemistry, tumor cells were diffusely positive for vimentin and S-100 and negative for smooth muscle actin, desmin, myogenin cytokeratin, epithelial membrane antigen, melan A, HMB-45, CD10, glial fibrillary acid protein inhibin, synaptophysin, chromogranin, MIC2, FLI-1, and neuron-specific enolase. Diagnosis of an epithelioid MPNST was offered. The case is presented in view of its rarity and also to highlight the value of immunohistochemistry in objectively identifying unusual sarcomas at uncommon sites.     

Fine-needle aspiration cytology of pleuropulmonary blastoma: a case report with unusual features.

Pleuropulmonary blastoma (PPB) is a rare and aggressive intrathoracic neoplasm of childhood, typically presenting as a pulmonary and/or pleural-based mass with cystic, solid, or combined features. Histologically, the tumor is well characterized with a mixture of primitive mesenchymal and variably differentiated sarcomatous components, and the cytologic features described in the three previous reports are also compatible to the histologic ones. Now, we present another case of PPB showing unusual features. A 3-yr-old boy presented with a pleural- or chest wall-based tumor. The fine-needle aspiration cytologic smears were highly cellular with poorly differentiated cells showing variable size and shape rather than those of typical blastemal cells. The histologic findings were also distinctive, exhibiting diffuse sheets of poorly differentiated cells without typical blastemal cell component. Diagnosis was confirmed by the support of immunohistochemical and ultrastructural features. The patient underwent a typical aggressive clinical course to death within 8 mo after diagnosis.     

恶性外周神经鞘瘤52例临床病理分析

目的观察恶性外周神经鞘瘤的临床病理学特征、诊断及鉴别诊断。方法回顾性分析52例恶性外周神经鞘瘤的临床病理学及免疫表型特征并复习相关文献。结果 52例患者中,男女发病率为1∶1,年龄4~71岁,头颈部18例(35%),四肢12例(23%),躯干9例(17%),深部组织8例(15%),椎管内4例(8%),生殖道1例(2%)。镜下肿瘤组织呈束状或漩涡状排列,瘤细胞短纺锤形、卵圆形、梭形,核分裂象易见。免疫表型:瘤细胞局灶表达S-100蛋白,Ki-67增殖指数10%~70%。结论恶性外周神经鞘瘤罕见,侵袭性高,预后差,其组织形态复杂多样,需与滑膜肉瘤、纤维肉瘤、血管外皮瘤、富于细胞性神经鞘瘤、纤维型脑膜瘤以及平滑肌肉瘤等鉴别。     

Fine-needle aspiration cytology of primitive neuroectodermal tumor of the urinary bladder: a case report

Primitive neuroectodermal tumors (PNETs) are malignant small round cell tumors, which exhibit a variable degree of neural differentiation. These tumors are usually found in the extraosseous soft tissue and rarely in bones. Occasional cases of PNETs of the urinary bladder have been reported on histopathology. However, to the best of our knowledge, none have been diagnosed on fine-needle aspiration cytology (FNAC). A patient presented to the out-patient department with complaints of a slowly progressive lump in the lower abdomen, which was diagnosed as PNET on FNAC. The smears showed a dispersed population and sheets of malignant small round cells with focal rosette formation and perivascular arrangement of tumor cells. Periodic acid-Schiff staining showed strong cytoplasmic positivity. Immunocytochemistry of the cytology smears also showed strong membrane positivity for CD99 (MIC-2), which was also confirmed on histopathological examination. PNET of the urinary bladder is a distinct entity, which can be diagnosed on FNAC and confirmed by immunohistochemistry. A diagnosis of PNET should be considered as a differential diagnosis in urinary bladder masses, especially in adolescents and young adults.