Usefulness of Electron Microscopy in the Diagnosis of “Small” Round Cell Tumors of the Sinonasal Region

The sinonasal region is known to harbor several types of tumors that belong to the general category of “small” round cell tumors and offer considerable diagnostic challenges. This study evaluated 33 cases of such tumors by electron microscopy to characterize their ultrastructural features in conjunction with immunohistochemistry, in an attempt to define diagnostic criteria of various types. Electron microscopy was useful in the proper classification of tumors in 27 cases: esthesioneuroblastoma (EN), 12; undifferentiated carcinoma, 6; melanoma, 3; lymphoma, 3; melanotic neuroectodermal tumor, 1; rhabdomyosarcoma, 1; and pituitary adenoma, 1. In the remaining six cases, the ultrastructural features were those of poorly differentiated carcinomas. They usually exhibited some epithelial characteristics as well as neuroendocrine features by immunohistochemistry and electron microscopy. These tumors could be best described as poorly differentiated neuroendocrine carcinomas (malignant neuroepitheliomas). The most controversial diagnostic problems existed between the tumors categorized as esthesioneuroblastomas and neuroendocrine (NE) carcinomas. Esthesioneuroblastomas were characterized by uniform round nucleated cells with variable amounts of dendritic processes containing numerous dense core granules ranging from 150 to 350 nm in the perikarya and dendritic processes. Dendritic processes contained longitudinally arranged neural tubules and revealed an occasional synaptic junction. In three of the 12 cases of EN, cells with the appearance of sustentacular cells were recognized by electron microscopy. The NE carcinomas usually consisted of closely packed round cells with scanty cytoplasm that lacked any feature of neuroblastic cells. The tumor cells in this category often were epithelioid in appearance and exhibited a varying degree of cytokeratin positivity. Neuron-specific enolase was also positive in all cases, further suggesting their neuroepithelial nature. The greatest difference between EN and NE carcinomas was the absence of sustentacular cells in NE carcinomas. Immunohistochemical and electron microscopic studies are essential in the differential diagnosis of EN and NE carcinomas, because their microscopic appearance is very similar. The study indicates that EM is useful in the diagnostic categorization of sinonasal tumors of uncertain nature, particularly when it is used in conjunction with immunohistochemistry.     

hASH1 expression is closely correlated with endocrine phenotype and differentiation extent in pulmonary neuroendocrine tumors.

The human homolog 1 of the Drosophila neurogenic achaete-scute genes, hASH1, is specifically expressed in fetal pulmonary neuroendocrine cells and in some neuroendocrine tumor cell lines. However, no data have been gathered regarding its in vivo expression in tumors. hASH1 mRNA expression was investigated by in situ hybridization in 238 surgically resected lung carcinomas, and the correlations between hASH1 expression status and immunostaining results of neuroendocrine markers chromogranin A, neural cell adhesion molecule, gastrin-releasing peptide and calcitonin, and clinical outcome were analyzed. hASH1 expression was detected in 2/20 (10%) adenocarcinomas, 4/30 (13.3%) typical carcinoids, 11/13 (84.6%) atypical carcinoids, 38/67 (56.7%) large-cell neuroendocrine carcinomas and 56/78 (71.8%) small-cell carcinomas, respectively, but not in any squamous cell carcinoma (0/21) or large-cell carcinoma (0/9). The 2 hASH1+ adenocarcinomas also expressed multiple neuroendocrine markers. Thus, hASH1 expression was restricted to lung cancers with neuroendocrine phenotypes. However, not all neuroendocrine tumors expressed hASH1. Within the entities of large-cell neuroendocrine carcinoma and small-cell carcinoma, hASH1 expression correlated very closely with chromogranin A, gastrin-releasing peptide and calcitonin expression (P<0.0001, r=0.852), but was not related to neural cell adhesion molecule expression (P=0.8892), suggesting that hASH1 expression, at least in lung cancer, is associated with endocrine phenotype expression other than 'neuroendocrine differentiation' in a broad sense. The fact that hASH1 was virtually absent in almost fully differentiated typical carcinoids, but was expressed in most, if not all, less differentiated atypical carcinoids as well as large-cell neuroendocrine carcinomas and small-cell carcinomas, suggests that hASH1 expression in lung cancer imitates its early and transient expression in fetal development, and that hASH1 is instrumental in the establishment, but not in the maintenance, of a cellular endocrine phenotype. Finally, hASH1 expression correlated with a significantly shortened survival in small-cell carcinoma patients (P=0.041).     

Trisomy 8 in primary esthesioneuroblastoma.

Esthesioneuroblastoma is a rare malignancy believed to be derived from neuroectodermal stem cells within the olfactory epithelium. We have obtained the karyotype of a primary esthesioneuroblastoma following brief (7-day) in vitro culture, and have determined that the only observable cytogenetic anomaly is the presence of an additional chromosome 8. Previously, the karyotypes of two cell lines established from metastatic esthesioneuroblastomas have been reported to contain the equivalent of three copies of chromosome 8, in addition to other chromosomal aberrations, including the reciprocal translocation, t(11;22)(q24;q12). Examination of the cytogenetic literature suggests that an extra copy of chromosome 8 is a common occurrence in undifferentiated small round cell tumors frequently observed to carry the t(11;22), including esthesioneuroblastoma, Ewing's sarcoma, peripheral neuroepithelioma, Askin's tumor, and rhabdomyosarcoma. These data, combined with our report of a small round cell tumor with the karyotype 47,XY, +8, indicate that trisomy 8 may be a common phenomenon in these tumors, and may also provide some sort of selective advantage to these tumor types.     

FLI-1在小圆细胞肿瘤鉴别诊断中的应用

目的研究FLI-1和CD99在小圆细胞肿瘤中的表达情况,探讨二者在小圆细胞肿瘤鉴别诊断中的应用价值。方法对46例小圆细胞肿瘤进行FLI-1和CD99免疫组化标记,并结合临床与病理组织学进行对比研究。结果FLI-1在Ewing肉瘤／外周原始神经外胚叶肿瘤（EWS／PNET）中阳性表达率为90．5％（19／21）,在分化差的滑膜肉瘤、横纹肌肉瘤分别为14．3％（1／7）、22．2％（2／9）,而在嗅神经母细胞瘤和间叶软骨肉瘤均无表达。CD99在EWS／PNET中阳性表达率为95．2％（20／21）,在分化差的滑膜肉瘤、横纹肌肉瘤、嗅神经母细胞瘤和间叶软骨肉瘤分别为71．4％（5／7）、66．7％（6／9）、75．0％（3／4）和60％（3／5）。FLI-1标记在EWS／PNET的敏感性为90．5％,特异性为88％;而CD99在EWS／PNET的敏感性为95．0％,特异性为32％。FLI-1在EWS／PNET中的特异性明显高于CD99（P〈0．05）。结论FLI-1在EWS／PNET诊断中的价值优于CD99,并且可用于小圆细胞肿瘤的鉴别诊断。     

NKX3.1 a useful marker for mesenchymal chondrosarcoma: An immunohistochemical study

IntroductionMesenchymal chondrosarcoma is a rare subtype of chondrosarcoma. The tumor has a characteristic bimorphic pattern with areas of poorly differentiated small round cell component and interspersed islands of well differentiated hyaline cartilage. Histological diagnosis of mesenchymal chondrosarcoma is very challenging especially in small biopsies when tumor presents with little cartilaginous component. In such cases, it is very difficult to distinguish mesenchymal chondrosarcoma from other round blue cell tumors like Ewing's sarcoma, rhabdomyosarcoma, small cell osteosarcoma and desmoplastic round blue cell tumor. Immunohistochemically, mesenchymal chondrosarcoma stains positive for NKX2.2, CD99, S100 and SOX9. This immunoprofile is non-specific and overlaps with other round blue cell tumors. Till recently, there was no reliable immunohistochemical marker to differentiate mesenchymal chondrosarcoma from other round blue cell tumors.NKX3.1, though widely used as a diagnostic biomarker for prostatic adenocarcinoma, has been recently proposed by Yoshida et al. (2020) as a unique marker of mesenchymal chondrosarcoma and EWSR1-NFATC2 sarcoma.ObjectiveThe aim of our study was to further explore utility of NKX3.1 as a diagnostic marker of mesenchymal chondrosarcoma.Material & methodsWe applied NKX3.1 immunohistochemistry to 21 cases of mesenchymal chondrosarcoma and 32 cases of other round blue cell tumors.Results14 out of 21 cases (66.7%) of mesenchymal chondrosarcoma stained positive for NKX3.1 with nuclear expression in small round component. Cartilaginous component was predominantly negative. All other round blue cell tumors showed negative results.ConclusionBased on our study results we suggest that NKX3.1 is a useful immunohistochemical marker in differentiating mesenchymal chondrosarcoma from its histological mimics.     

hASH1基因与肺神经内分泌肿瘤的关系

肺神经内分泌肿瘤(neuroendocrine tumor，NET)是由具有多向分化潜能的肿瘤细胞组成，这些肿瘤细胞具有分泌多种活性激素的功能。肺NET的发生、发展与hASH1(human achaete-scute homologue 1), MEN1(multiple endocrine neoplasia type 1), pRB和E2F1等基因相关，其中hASH1基因成为近年来研究的热点，该基因能促进肺NET的内分泌分化，降低肿瘤的分化程度，并且有临床资料显示hASH1基因的表达还与小细胞肺癌的低生存率有关，可以作为临床预后的一个标准。     

Poorly differentiated follicular thyroid carcinoma with rhabdoid phenotype: a clinicopathologic, immunohistochemical and electron microscopic study of two cases.

Poorly differentiated thyroid carcinomas with follicular cell phenotype are not well defined. Different diagnostic criteria have been employed for these tumors, including solid growth, nodular, trabecular, and insular patterns. Cytologic features, such as a predominance of tall and columnar cells, have been considered to be diagnostic of poorly differentiated carcinoma. However, there is no agreement among surgical pathologists regarding morphologic criteria for poorly differentiated thyroid carcinoma. We report two unique thyroid neoplasms that we interpreted as poorly differentiated follicular carcinomas. Nodular, trabecular, and sheetlike patterns predominated in both tumors. They were composed of cells that were focally immunoreactive for thyroglobulin and had large vesicular nuclei with prominent nucleoli. A variable number of cells showed rhabdoid phenotype. The rhabdoid inclusions did not stain for thyroglobulin but contained whorls of intermediate filaments that were vimentin positive. There were foci of necrosis and numerous mitotic figures. Both patients were adults and died with multiple pulmonary metastases. The presence of rhabdoid cells in poorly differentiated follicular carcinomas broadens the spectrum of tumors with rhabdoid phenotype. More cases are needed to determine whether the rhabdoid phenotype is a marker for poorly differentiated follicular carcinoma as well as an independent adverse prognostic factor.     

低分化滑膜肉瘤临床病理及分子遗传学研究

目的：研究低分化滑膜肉瘤的临床病理学特点及其分子遗传学表现。方法：收集低分化滑膜肉瘤标本121例，采用形态学观察和免疫组化染色，并用RT－PCR方法在石膜包埋组织中检测SYT－SSX融合mRNA表达。结果：12例低分化滑膜肉瘤中细胞型4例，大细胞型6例，高度恶性梭形细胞型2例。8例有随访资料其中4例死于肿瘤，平均生存时间18个月。免疫组化表现为CK和（或）EMA阳性，以EMA阳性率较高，同时vimentin阳性。S－100蛋白也有较高阳性率，多呈局灶或散在阳性。RT－PCR方法均可检测到SYT－SSXmRNA表达，对照组12例肿瘤包括恶性周围神经 鞘膜瘤、尤因肉瘤和恶性血管外皮瘤SYT－SSX检测全部阴性。结论：低分化滑膜肉瘤有其形态学及免疫表型特点，分子遗传学检测SYS－SSX融合mRNA有助于诊断和鉴别诊断。     

Expression of vascular endothelial growth factor in human gastric carcinomas

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is a secreted protein which may play a pivotal role in tumor-associated microvascular angiogenesis and hyperpermeability. The expression of mRNA for VEGF was examined in eight gastric carcinoma cell lines and 30 gastric carcinoma tissues as well as corresponding normal mucosa. All the cell lines expressed VEGF mRNA at various levels that correlated well with the amounts of VEGF secreted into the condition medium. The expression of VEGF mRNA by TMK-1 cells was increased by the treatment of epidermal growth factor (EGF) or interleukin-1α (IL-1α), whereas it was decreased by the treatment of interferon-β (IFN-β). In gastric carcinoma tissues, the level of VEGF mRNA in primary tumors was higher than that in the corresponding normal mucosas in six (46%) of 13 well-differentiated adenocarcinomas and in two (12%) of 17 poorly differentiated adenocarcinomas, respectively. Vessel counts in well-differentiated adenocarcinomas had a tendency to be higher than those in poorly differentiated adenocarcinomas. In well-differentiated adenocarcinomas, the levels of VEGF mRNA expression tended to be higher in carcinomas of advanced stage than in early stage carcinomas. Both in situ mRNA hybridization and immunohistochemistry demonstrated the presence of VEGF expression within the tumor cells. These results suggest that VEGF may confer angiogenesis and progression of human gastric carcinomas, especially of the well-differentiated type.     

An immunohistochemical analysis of cyclin D1, p53, and p21waf1/cip1 proteins in tumors originating from the follicular epithelium of the thyroid gland

This study aimed at clarifying the factors closely related to the tumor progression of thyroid neoplasms. We examined the immunoreactivity of cyclin D1, p53, and p21waf1/cip1 proteins in 179 thyroid tumors originating from the follicular epithelium using an immunohistochemical technique. Cyclin D1 positivity was frequent in well-differentiated thyroid carcinomas (39/122 cases), but it was rarely seen in follicular adenomas (1/33 cases), (p < 0.05). Positivity for p53 was more frequent in poorly differentiated carcinomas (7/19 cases) and undifferentiated carcinomas (4/5 cases) than in well-differentiated carcinomas (14/122 cases) (p < 0,05, respectively). P21waf1/cip1 positivity was more frequent in well-differentiated thyroid carcinomas (43/122 cases) than in follicular adenomas (4/33 cases) (p < 0.05). Regarding the relationships of these proteins, co-positivity for cyclin D1 and p53 was observed more often in poorly differentiated carcinomas (5/7 cases) than in well-differentiated carcinomas (7/39 cases) (p < 0.05). Most cases with cyclin D1 positivity did not show p21waf1/cip1 expression in poorly differentiated carcinomas (6/7 cases). Three cases examined showed co-positivity of p53 and p21waf1/cip1. Our results suggest that cyclin D1 is invoved in thyroid oncogenesis. Moreover, p53 might be closely related to the development of poorly differentiated carcinomas and undifferentiated carcinomas originating from well-differentiated carcinomas.     

Neuroectodermal neoplasms of the head and neck with emphasis on neuroendocrine carcinomas.

Tumors exhibiting neuroectodermal differentiation occur throughout the body, and the diverse tissues of the head and neck give rise to a wide assortment of these neoplasms. Neuroectodermal neoplasms may be divided into lesions showing primarily epithelial differentiation (Group I, neuroendocrine carcinomas) and a more diverse group (Group II) of nonepithelial neoplasms. This article reviews these neuroectodermal tumors of the head and neck with emphasis on the neuroendocrine carcinomas and their nomenclature. The author believes that with regard to Group I tumors, the older terminology of carcinoid, atypical carcinoid, and small cell carcinoma should be replaced by subclassifications of well-differentiated, moderately differentiated, and poorly differentiated neuroendocrine carcinoma. The latter category should be further subdivided into small cell and large cell variants. Neuroendocrine carcinomas, particularly the moderately differentiated subtype, are often underdiagnosed in the head and neck region. In the larynx, these tumors are the most common form of nonsquamous carcinoma. Poorly differentiated neuroendocrine carcinoma of small cell type is most common in the salivary glands but can occur elsewhere in the region. The large cell subtype of poorly differentiated neuroendocrine carcinoma has not been well documented in this region. However, the most likely candidate for this tumor category is the so-called sinonasal undifferentiated carcinoma. Group II tumors discussed include olfactory neuroblastoma, malignant melanoma, and Ewing's sarcoma. In addition, differential diagnostic problems related to Group I and II tumors are reviewed in detail. This article reviews and updates our understanding of neuroectodermal neoplasms arising in the head and neck. The focus is on tumors that exclusively involve this region or show a strong predilection to occur here.     

Molecular characterization of intraductal breast carcinomas

 In situ duct carcinoma (DCIS) is a heterogeneous group of lesions which has recently been subdivided into three types: well-differentiated (type I), intermediately differentiated (type II) and poorly differentiated (type III) DCIS. Fourteen cases of DCIS and 11 of DCIS with minimal invasion were analysed for mRNA levels of β-actin, EGFR, c-cerbB2, MTS1, k-ras, RB, BRCA1, cyclin E, and c-myc genes. A microdissection technique was used on paraffin-embedded tissue. A statistically significantly higher expression of cyclin E oncogene and MTS1 tumor suppressor gene was seen in type III DCIS than in the other types, while no significant differences in the mRNA expression patterns of the other genes were observed. These data are consistent with the fact that poorly differentiated DCIS is a readily recognizable class of tumours that have a particularly aggressive behaviour and probably unique histogenesis. Received: 21 July 1997 / Accepted: 11 October 1997     

Cytogenetic and pathologic aspects of Ewing's sarcoma and neuroectodermal tumors.

Diagnostic classification of poorly differentiated, round cell, primitive neuroectodermal neoplasms, including Ewing's sarcoma, peripheral neuroepithelioma, Askin's tumor, and esthesioneuroblastoma, is challenging to the surgical pathologist using conventional histopathologic approaches because of very similar and overlapping morphologic and cytologic features. Furthermore, distinguishing these neoplasms from neuroblastoma, embryonal rhabdomyosarcoma, small cell osteogenic sarcoma, and non-Hodgkin's lymphoma can be difficult. This paper describes and reviews the cytogenetic and molecular genetic changes in these tumors and demonstrates how the ability to detect these changes has enabled a greater understanding of the histogenesis, classification, diagnosis, and prognosis of these neoplasms.     

NKX3.1和NKX2.2在间叶性软骨肉瘤中的表达及诊断价值

目的探讨NKX3.1和NKX2.2在间叶性软骨肉瘤(mesenchymal chondrosarcoma, MC)中的免疫组织化学表达情况及两者在MC和其他类型小圆细胞恶性肿瘤中的鉴别诊断价值。方法收集解放军东部战区总医院2001—2020年诊断的12例MC和97例其他小圆细胞恶性肿瘤, 进行NKX3.1和NKX2.2免疫组织化学检测, 其中在12例MC中采用两种NKX3.1抗体[兔多克隆抗体和兔单克隆抗体(克隆号EP356)]进行检测, 在97例其他小圆细胞恶性肿瘤中采用一种NKX3.1抗体(兔多克隆抗体)进行检测, 并复习相关文献。结果 12例MC患者女性7例, 男性5例, 平均年龄33岁(范围14～54岁)。其中9例来源于骨, 3例来源于软组织。12例MC患者8例术后出现复发或转移, 其中3例死亡。12例MC组织学上均具有典型的双向分化特征。免疫表型上, NKX3.1两种抗体在MC中的阳性比例均为12/12;NKX3.1(兔多克隆抗体)在12例软骨肉瘤(3级)、5例腺泡状横纹肌肉瘤、5例胚胎性横纹肌肉瘤和5例孤立性纤维性肿瘤中各1例局灶弱阳性, 余70例其他小圆细胞恶性肿瘤均阴性...     

A retrospective analysis of immunohistochemical staining in identification of poorly differentiated round cell and spindle cell tumors--results, reagents and costs.

Immunohistochemistry has rapidly established a significant role in diagnostic pathology. We use immunohistochemistry as an adjunct to morphological diagnosis and employ a "panel approach" to the classification of poorly differentiated tumors. This retrospective analysis was conducted to examine the efficacy of such an approach, using, as an example, the two most common categories of poorly differentiated tumors, namely, the poorly differentiated round cell tumors and spindle cell tumors. Five hundred and fifty-seven consecutive cases of such tumors, collected over a two-yr period, had been subjected to immunohistochemical staining because specific or definitive categorization of the tumor was not possible on the basis of the examination of hematoxylin and eosin stained sections. The clinical history, gross and microscopic findings, as well as the results of immunohistochemical stains were analyzed. Immunohistochemistry allowed a definitive diagnosis to be assigned in 420 cases (75.4%). It was particularly useful in identifying malignant melanoma of both epithelioid and spindle types and distinguished between melanoma, lymphoma and poorly differentiated carcinoma in 126 cases of such lesions occurring in adult lymph nodes. It was also useful in identifying tumors in small biopsies where poor cytomorphological preservation or small size precluded accurate categorization. The application of appropriately chosen panels of antibodies tailored to a narrow list of differential diagnoses helped to identify myogenous, vascular, nerve sheath and fibrocystic lesions among the group of spindle cell tumors. Immunohistochemistry provided definitive diagnoses in 70% of round cell tumors and 92% of spindle cell tumors.(ABSTRACT TRUNCATED AT 250 WORDS)