Electron microscopic and immunohistochemical studies of gastrointestinal stromal tumors

Sixteen gastrointestinal stromal tumors (GISTs) were studied by immunohistochemical analysis and an ultrastructural procedure. The tumor locations were as follows: esophagus (2), stomach (7), small intestine (3), and large intestine (4). Four of the lesions were classified as malignant, 2 as borderline, and 10 as benign. On the basis of the immunohistochemical analysis, the tumors were classified as follows: 1 as myogenic type, 2 as Schwann cell type, 8 as Cajal cell type (including 2 gastrointestinal autonomic nerve tumors, GANTs), and 5 as mixed-cell type. In each subtype the phenotype was compared to the ultrastructural findings. Myogenic and Schwann cell type revealed ultrastructurally smooth muscle differentiation and schwannian tumor. All 8 tumors of the Cajal cell type revealed interdigitating cytoplasmic processes with occasional clusters of filopodia. Two tumors were subdivided as GANT. Five tumors of mixed-cell type were composed of a mixture of cells with variable myogenic features or variable neural differentiation. We confirmed in this study that immunohistochemical analysis reflected electron microscopic findings.     

APUD and mast cells of the gastrointestinal system: immunohistochemical and ultrastructural identification

A rationale for sequential immunohistochemical studies of the endocrine function of APUD cells is described, as exemplified by a study of serotonin-containing cells in rat small intestine, involving preparation of paraffin and semithin sections of epoxide resin-embedded tissue, followed by electron-microscopic examination of cells detected by the immunoperoxidase technique. With the approach described, it has been shown that a positive immunohistochemical reaction to antiserotonin antiserum is given, along with EC cells, by those mast cells disposed in groups near the EC cells as well as among connective-tissue cells of villi under the basement membrane. It is suggested that by collecting and accumulating the serotonin synthesized by specialized EC cells, mast cells transport it to sites of utilization as required by the specific arrangement.     

Pulmonary carcinosarcoma: immunohistochemical and ultrastructural studies

A case of pulmonary carcinosarcoma in a 68-year-old male patient is reported. The tumor in the resected left upper lobe extended mainly endobronchially, invading the normal bronchial lumina and mucosa. The carcinomatous component consisted of poorly differentiated squamous cell carcinoma and was mainly located in the periphery of the tumor nests. The sarcomatous component consisted of chondrosarcoma and was mainly located in the center of the tumor nests. Tumor cells in the sarcomatous component reacted with anti-S-100 protein antibody and were surrounded with abundant homogeneous extracellular matrix staining positively with Alcian blue. The transition from the carcinomatous component to the sarcomatous component appeared to be very smooth. The tumor cells in both the carcinomatous and sarcomatous components reacted with anti-epithelial membrane antigen antibody. Ultrastructurally, the tumor cells with tonofibrils in the carcinomatous component were apposed and connected to each other by desmosomes. By contrast, in the sarcomatous component, the tumor cells had well-developed and dilated rough endoplasmic reticulum and were arranged loosely in a myxomatous matrix. Some tumor cells in the sarcomatous component had occasional tonofibrils, and were apposed and connected to each other by desmosome-like structures. It is shown for the first time, ultrastructurally and immunohistochemically, that the tumor cells in the sarcomatous component of pulmonary carcinosarcomas have features of both epithelial and mesenchymal cells. It is suggested that the sarcomatous component in the present case is derived from the carcinomatous component.     

Glucagon and glucagon-like immunoreactive cells in mid- and hindgut carcinoids

The occurrence of glucagon/glucagon-like immunoreactivity in 31 small intestinal, 34 rectal and 18 appendiceal carcinoids were investigated immunocytochemically using, sequence specific antisera. Glucagon/GLI immunoreactive cells were found in five small-intestinal and five rectal carcinoids, but none were observed in any of the appendiceal carcinoids examined. Glucagon/GLI immunoreactive cells constituted a minor cell population, except in one rectal carcinoid, where most of the tumour cells were of this type. Glucagon/GLI immunoreactive cells were detected with only some sequence-specific antisera, and not with antisera directed against the rest of the glucagon/glicentin molecule. This might indicate that these cells contain a molecule which shares some antigenic binding sites with glucagon/glicentin rather than genuine glucagon/glicentin. It is concluded that this finding contributes to explain why hindgut carcinoids rarely give rise to symptoms related to neuro-endocrine product(s).     

Gastrointestinal autonomic nerve tumors: Immunohistochemical and ultrastructural studies in cases of gastrointestinal stromal tumor

The gastrolntestlnal autonomic nerve tumor (GAN tumor) is an uncommon stromal tumor with a morphological feature resembling the cell processes of the enteric plexus, and was originally teimed a plexoma or plexosarcoma. Light microscoplc studies show the GAN tumor most often consists of spindle-shaped cells indistinguishable from a smooth muscle tumor or Schwann cell tumor. Immunohistochemical and ultrastructural examinations of 18 cases of gastrointestinal stromal tumor (GIST) were performed. During ultrastructural examination, all of the 12 cases which were immunohisto-chemically positive for S-100 protein or neuron-specific eno-lase (NSE) showed synapse-like structures containing dense core neurosecretory granules measuring 100–200 nm, and 40–60 nm endocytoplasmic vesicles. These results suggest that most GIST of neurogenlc origln are tumors derived from the myenteric nerve plexus.     

An ultrastructural and immunohistochemical evaluation of cytodifferentiation in neuroblastic tumors

Twenty-six cases of neurogenic tumors consisting of 2 ganglioneuromas (GN), 8 ganglioneuroblastomas (GNB), and 16 neuroblastomas (NB) were studied to evaluate their cytodifferentiation. Ultrastructurally, a moderate to large number of neuritic processes and high density neurosecretory granules (NSG) were found in all cases of GN and well-differentiated GNB, in two-thirds of poorly differentiated GNB, in about a half of rosette-fibrillary NB, and in no case of round-cell NB. All GN and GNB had tumor cells which were positive for both chromogranin and neurofilaments. Of the 16 cases of NB, 12 were positive for chromogranin, and 13 and 15 were positive for Mr 200,000 and 68,000 neurofilament polypeptides, respectively. However, both markers appeared mainly in tumor cells maturing toward neuroblasts. Electron microscopy was helpful for the diagnosis of undifferentiated NB in those cases immunohistochemically negative for chromogranin or neurofilaments. We conclude that ultrastructural and immunohistochemical examinations are useful for the morphologic assessment of the degree of maturation of neuroblastic tumors.     

Malignant melanoma in the oral region: ultrastructural and immunohistochemical studies

Malignant melanoma in the oral region is reviewed in its clinicopathological aspects. Clinically the melanomas were classified into five types; however, there were no histopathological differences according to these clinical types. Electron microscopic observation of the melanomas and primary culture cells derived from oral malignant melanoma revealed that, in patients whose prognoses were relatively good, many mature-stage melanosomes were found. Immunohistologically, there was a positive reaction for transferrin receptor and the expression of pRb2/p130 was found in only 2 of 13 patients, who are still alive after periods of over 14 years. The radiosensitivity of a cell line derived from human oral malignant melanoma was greater than that in cell lines derived from human cutaneous melanoma and with radiation, the number of melanosomes increased. There are very few clinical cases of oral malignant melanoma and very few cell lines derived from oral malignant melanoma, and so findings in these patients and these cell lines should be accumulated in order to clarify the biological behavior of oral malignant melanoma.     

Histopathological and immunohistochemical features of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal tract. Major advances in their definition and classification and the understanding of their molecular mechanisms have recently been made. These advances have become a model of targeted therapy in oncology. The diagnosis of GISTs relies on histological arguments - proliferation of spindle cells, seldom of epithelioid cells or both spindle and epithelioid cells - and on immunohistochemical arguments - expression of CD117 usually associated with CD34 expression. The evaluation of the prognosis is essential and based on a simple algorithm using two prognostic parameters, tumor size and mitotic index. The aim of this paper is a complex histopathological assessment, using both classic and modern (immunohistochemistry) techniques, of the GISTs comprised in the study. GISTs occur mainly in older adults (median age 60-69 years), anywhere along the gastrointestinal tract but also retroperitoneal. Most of them were nodular (75%), tumor necrosis and mucosal ulceration being the most frequent encountered secondary alterations; these modifications proved to be significantly correlated with large tumor size and high malignancy. Immunohistochemical evaluation revealed that 77 (97%) cases of GISTs presented a positive reaction for CD117, 50 (63%) cases were positive for CD34, 19 (24%) were positive for SMA and only 10 (13%) were positive for S100. Immunohistochemical evaluation remains an important tool of pathology in the diagnosis of GISTs, in the differential diagnosis from other gastrointestinal mesenchymal tumors and represents the gold standard for diagnosis of these tumors and an eligibility criterion for imatinib therapy.     

Elastosis in lung carcinoma: immunohistochemical, ultrastructural and clinical studies

Elastosis is the pathological finding of focal deposits of elastic fibers in abnormal amounts within tissue. It is well described in the case of infiltrating carcinoma of the breast, but elastosis in lung carcinoma has not been previously documented in detail. We investigated the characteristics of elastosis in lung carcinoma with light and electron microscopies, and immunohistochemistry for alpha-1-antitrypsin. A total of 184 surgically resected primary lung carcinomas were studied. Elastosis was detected in adenocarcinomas (85/106), squamous cell carcinomas (11/60) and adenosquamous carcinomas (5/7), but not in small-cell carcinomas (n = 4) or large-cell carcinomas (n = 5). The degree of elastosis in each case was divided into one of five grades, graded as 3+ to 1-. The score of elastosis was significantly higher in adenocarcinoma than that in squamous-cell carcinoma (P<0.01). In the cases of adenocarcinoma, the mean score of elastosis in the well-differentiated type (WD n = 43) was higher than that in the moderately differentiated (MD) (n = 39; P = 0.012) and poorly differentiated (PD) types (n = 24; P<0.01). The mean score of elastosis in MD adenocarcinoma was also higher than that in the PD type (P<0.01). Light- and electron-microscopic analyses revealed that these elastic fibers in elastosis were composed of aggregates of thick mature and fine immature elastic fibers, and were positive for alpha-1-antitrypsin. It is suggested that both degraded elastic fibers and newly synthesized fibers are contained in the elastosis of lung carcinoma. Although no significant evidence was detected to suggest any correlation between elastosis and the degree of tumor invasion, the survival curves of adenocarcinomas with elastosis showed a significantly improved prognosis than of those without elastosis in the cases of stages IA and IB (n = 52; P = 0.026).     

Perivascular myoma: case report with immunohistochemical and ultrastructural studies

A subcutaneous myopericytoma-type perivascular myoma arising in the elbow of a 61-year-old woman is described. The tumor was well demarcated and consisted microscopically of small ovoid and spindle cells arranged in a concentric fashion, surrounding small to medium-sized vessels and imparting a superficial resemblance to hemangiopericytoma. In some areas, the cellular whorls were separated by myxoid stroma. Cells located between cellular whorls appeared immature with scant cytoplasm but did not show distinct nuclear anaplasia, increased mitoses or foci of necrosis. Immunohistochemistry showed that constituent cells were positive for alpha-smooth muscle actin and desmin. Electron microscopy disclosed that the immature-looking cells, as well as the ovoid and spindle-shaped cells, possessed focal densities along with thin filaments, subplasmalemmal densities, pinocytotic vesicles and an external lamina. These ultrastructural and immunohistochemical features indicate a myoid nature of pericytic cells and justify this type of neoplasm being categorized as perivascular myoid tumor.     

胃肠道间质瘤临床病理及免疫组织化学特征

目的 探讨胃肠道间质瘤的免疫组织化学特征，为其诊断及鉴别诊断和预后提供依据。方法 对消化道内169例间叶源性肿瘤进行免疫组织化学标记和形态学观察，确诊113例胃肠道间质瘤。结果 肿瘤多见于胃，临床常见首发症状为消化道出血及腹部包块。瘤细胞主要有梭形细胞及上皮样细胞两种形态，梭形细胞型70例，上皮样细胞型10例，混合细胞型33例。相对良性33例，交界性26例，恶性54例。免疫表型：CD117阳性112例，CD34阳性102例，阳性率分别为99．1％及90．2％，且呈弥漫强阳性表达。结论 胃肠道间质瘤是消化道最常见间叶源性肿瘤，以胃内多见；主要有2种细胞形态和3种组合形式；确诊需要依靠CD117、CD34等免疫标记物配合。     

Argyrophil, non-argentaffin carcinoids of the appendix vermiformis. Immunohistochemical and ultrastructural studies

Five argyrophil, non-argentaffin classical carcinoids of the appendix were found in 19 appendiceal classical carcinoids and were investigated histochemically, immunohistochemically and ultrastructurally. All tumors consisted entirely of argyrophil cells. Three of the five carcinoids were composed almost totally of peptide YY cells and were negative for serotonin. One of them consisted of peptide YY cells (60%), somatostatin cells (40%), and a few cells with glucagon-like immunoreactivity (GLI). The remaining one without peptides was homogeneously immunoreactive for serotonin alone. Ultrastructurally, each of the four peptide-positive carcinoids was composed of one kind of endocrine cell type with round secretory granules. Average diameter of granules were 150, 160, 190, and 210 nm, respectively. The non-argentaffin, serotonin-positive carcinoid showed predominant round secretory granules and a few irregular ones, both being 150 nm in largest diameter. It is suggested that the argyrophil, non-argentaffin carcinoids of the appendix are subdivided into two groups; carcinoids composed mainly of peptide (especially, peptide YY)-positive cells with round granules of D1 and/or L cell type and those of serotonin-positive cells with pleomorphic granules of ECn cell type.     

An immunohistochemical and clinicopathological study of gastrointestinal stromal tumors

Immunohistochemical and clinicopathological features of 58 gastrointestinal stromal tumors (GIST) were studied. One occurred in the esophagus, 41 in the stomach, nine in the small intestine, and seven in the large intestine. By using indirect immunoperoxidase staining for Cajal cell markers (c-kit protein and CD34), smooth muscle markers (alpha-smooth muscle actin, desmin, heavy caldesmon and calponin) and Schwann cell markers (S-100 protein and Leu 7), GIST were classified into five groups, such as Cajal cell type (n = 9), myogenic type (n = 5), Schwann cell type (n = 2), mixed cell type (n = 40) and undifferentiated type (n = 2). c-kit Protein (42/58; 72%) and CD34 (45/58; 78%) were commonly and diffusely expressed in GIST. Novel smooth muscle markers, caldesmon (29/58; 50%) and calponin (18/58; 31%), were useful in detecting myogenic characters of GIST. S-100 protein was expressed in 16 (28%) tumors, two of which were also reactive with Leu 7 (CD57). Three small bowel tumors with skeinoid fibers expressed the Cajal cell markers, and were categorizable in GIST. Clinicopathological analyses using aggressive (n = 21) and non-aggressive (n = 21) GIST indicated that the malignant potential was correlated with the intestinal location, large tumor size, high cellularity, necrosis, solid (non-interlacing bundled) pattern of growth, negativity of c-kit protein and/or CD34, high mitotic count, and high MIB-1 labeling.     

Histogenesis of unique elastinophilic fibers of elastofibroma: ultrastructural and immunohistochemical studies

Electron microscopy and both light and electron microscopic immunohistochemical tests for elastin were employed to study the morphogenesis of the unique elastinophilic fibers of an elastofibroma removed from the subscapular region of a 62-year-old woman. Ultrastructurally, as shown by tannic acid stain, elastinophilic fibers of the elastofibroma consisted of central cores and outer zones. The latter were composed of various sizes of vaguely demarcated, irregularly shaped amorphous components and compactly and randomly arranged large amounts of microfibrils. The electron microscopic immunohistochemical results showed that the small-sized amorphous components and microfibrils in the outer zones of the elastinophilic fibers were stained evenly and of granular texture, but the vaguely outlined large amorphous components were not stained. These findings were interpreted as indicating that the amorphous components of the outer zones of elastinophilic fibers were less compact and allowed the penetration of antielastin antibody. The unique elastinophilic fibers of elastofibromas appear not to be formed by the degeneration of the fibers but by abnormal elastogenesis, including an abnormal arrangement of microfibrils.     

Immunocytochemical demonstration of cytokeratin in gastrointestinal carcinoids and their probable precursor cells

Summary Occurrence and distribution of cytokeratin, neuron specific enolase (NSE) and actin were studied by the immunoperoxidase-antiperoxidase (PAP)-technique using specific antibodies in formalin-fixed, paraffin-embedded material from 6 cases of neurogenic appendicopathy with numerous endocrine cells in the mucosal stroma (SEC), 5 cases of microcarcinoidosis of the stomach, 12 gastrointestinal carcinoids and 4 bronchial carcinoids. Cytokeratin was detectable in all tumor cells. In addition, the epithelial endocrine cells (EEC) and the SEC of intestinal origin were cytokeratin positive. EEC, SEC and cells of microcarcinoids and carcinoids showed a positive immunoreactivity with antibodies to NSE, whereas actin antibodies did not reveal significant staining of these cells. These results strongly suggest that carcinoids of the gastrointestinal tract originate from SEC that have migrated downwards into the stroma from the epithelial layer (Endophytie according to Feyrter).Dedicated to Prof Dr. H.G. Klingenberg on the occasion of his 65th birthday.     

Angiogenic histogenesis of stromal cells in hemangioblastoma: ultrastructural and immunohistochemical study

Controversy regarding the origin of characteristic stromal cells (SC) is responsible for the placement of hemangioblastoma as a single entity in the category of "tumors of uncertain histogenesis" in the current WHO classification of brain tumors. This subclassification of hemangioblastoma is, to a large extent, a consequence of a remarkable antigenic heterogeneity of SC demonstrated in many, often contradictory immunohistochemical studies. In contrast, most of the electron microscopic studies demonstrated a number of features indicating angiogenic nature of SC and, therefore, hemangioblastoma. This study reevaluated the histogenesis of SC, applying immunohistochemistry as well as electron microscopy and immunoelectron microscopy. Immunohistochemical studies confirmed most of the previous results indicating a very frequent expression of vimentin, S-100 protein, neuron-specific enolase, and cytokeratins. SC were less commonly immunoreactive for desmin, factor XIIIa, and Ricinus communis lectin receptors, and only occasionally for factor VIII and Ulex europeus lectin. They were negative for other markers of endothelial, neuronal, glial, neuroendocrine, and smooth muscle differentiation. Approximately 1% of SC showed Ki67 immunoreactivity, indicating their slight proliferative activity, consistent with the benign nature of the tumor. In contrast to the inconclusive results of the immunohistochemistry, electron microscopy demonstrated a clear relationship of SC to endothelial cells, smooth muscle cells, and pericytes. Occasional SC were found within the vascular lumina. SC often showed intracellular caveolae consistent with the formation of early capillary lumina. Moreover, occasional SC contained small Weibel-Palade bodies positive for factor VIII in immunoelectron microscopy. SC represent a heterogenous population of abnormally differentiating mesenchymal cells of angiogenic lineage, with some morphological features of endothelium, pericytes, and smooth muscle cells. Occurrence of SC in hemangioblastoma could be related to a limited ability of angioformative stromal cells to develop an architecture of capillary lumina integrated with the vascular network of the tumor. Hemangioblastoma should be reclassified and included together with other vascular tumors of the central nervous system.     

Synovial sarcoma: ultrastructural and immunohistochemical features of epithelial differentiation in monophasic and biphasic tumors

Nineteen synovial sarcomas, six biphasic and 13 monophasic tumors, were examined by light and electron microscopy and immunohistochemically for the presence of the epithelial markers keratin and epithelial membrane antigen (EMA). Ultrastructurally, intercellular spaces with processes are present to varying degrees in the spindle cell component of all synovial sarcomas, and junctional specializations occur in most cases. Tumors of the two types differ in their content of external (basal) lamina, which encloses the epithelial component of all biphasic tumors and is detectable in the spindle cell component of two thirds of them, but is absent from the majority of monophasic tumors. Keratin and EMA were demonstrated in both components of all six biphasic tumors. Of the 13 monophasic tumors, keratin was present in nine, EMA in eight, and at least one epithelial marker in ten. Synovial sarcoma is regarded as a distinctive soft tissue tumor with variable epithelial-like differentiation. The use of electron microscopy can increase the specificity of immunohistochemical studies of soft tissue sarcomas and allow more accurate differentiation of monophasic synovial sarcoma from other spindle cell tumors, particularly those that do not express markers.     

副神经节瘤样脑膜瘤的临床病理观察

脑膜瘤是较为常见的、发生于脑膜部位的中枢神经系统的肿瘤.脑膜瘤的组织学类型比较多,近年来有文献报道了一种新的脑膜瘤类型.称为"副神经节细胞瘤样脑膜瘤",目前对该种脑膜瘤是否是一种新的类型还有争议[1].我们在外检工作中遇到4例,为了提高对该肿瘤的认识,报道如下,结合文献讨论其临床病理特点及诊断、鉴别诊断要点.     

Cerebellar basket cells of Creutzfeldt-Jakob disease: immunohistochemical and ultrastructural study

To elucidate possible abnormalities of cerebellar basket cells of Creutzfeldt-Jakob disease (CJD), seven sporadic cases were examined neuropathologically. Recently, parvalbumin-positive, GABAergic cerebral interneurons have been demonstrated to show early, selective loss in CJD, and the phenomenon is postulated as a cause of characteristic neurological symptoms of CJD. In this study, however, we demonstrated that the basket cells, cerebellar counterparts, were resistant even in patients with severe brain atrophy, and their processes showed intense argyrophilia and immunopositivity to phosphorylated neurofilament. They can newly be listed as CJD-resistant neurons similar to those of the hippocampus and brainstem nuclei. The mechanism to escape cell loss is of great interest, and there might be unknown factors modulating susceptibility within parvalbumin-positive neuronal subgroups. Furthermore, one case showed abnormal positivity with hematoxylin, crystal violet and pyronin in the basket cells. The pyronin positivity was reduced after ribonuclease digestion, suggesting that the causative substance was composed of RNA. Ultrastructurally, the fibers contained free ribosomes and amorphous electron-dense deposits. To our knowledge, such a finding has also not been previously reported.