Macroscopic,Histologic, Histochemical,Immunohistochemical, and Ultrastructural Features of Mesothelioma

Mesotheliomas are uncommon neoplasms that arise from the cells forming the serosal membranes of the body cavities. Approximately 90–95% of mesotheliomas arise in the pleural cavity and 5–10% in the peritoneal cavity. Rare mesotheliomas arise in the pericardium and in the tunica vaginalis. Unlike many neoplasms, mesotheliomas grow in a diffuse distribution and tend to encase the organs in the various body cavities. A combination of histochemical, immunohistochemical, and ultrastructural features are often necessary to accurately diagnose mesotheliomas. These techniques are highlighted in this review article on mesothelioma.     

Lymphohistiocytoid mesothelioma: a clinical, immunohistochemical and ultrastructural study of four cases and literature review

Lymphohistiocytoid mesothelioma (LHM) is a term proposed to designate a variant of mesothelioma that assumes a histiocytoid morphology and contains intense lymphocytic infiltrates. Reports on this variant are few, and its clinicopathologic and ultrastructural characteristics are still to be defined. The authors have studied 4 such cases that were identified among 120 mesotheliomas in the electron microscopy (EM) files of a single institution between 1982 and 2002. Histologically, all 4 lesions were composed of diffuse proliferations of cells with a histiocytoid appearance, admixed with an intense lymphocytic infiltrate. All 4 were associated with an unequivocal sarcomatoid component. Immunohistochemical (IHC) studies showed that the majority of histiocytoid cells were positive for CD68 and vimentin in all 4 cases, suggesting fibrohistiocytic differentiation. Immunoreactivity for calretinin and AE1:AE3 was only very focally identified in 3 of 4 cases. All cases were negative for CEA (M), Leu-M1, and B72.3. The lymphocytic component in all 4 cases was almost entirely composed of CD3- and CD8-positive, small, mature T cells, with only a minor component of CD20-positive cells and occasional eosinophils. Although all cases contained numerous CD68 positive atypical cells, co-expression of CD68 and either calretinin or keratin by individual cells was difficult to demonstrate by immunohistochemistry. Ultrastructurally, 3 of the 4 cases demonstrated very focal mesothelial differentiation as evidenced by long and slender surface microvilli, including the case with negative immunoreactivity for calretinin and cytokeratin. Review of the literature yielded 6 additional LHM cases. Analysis of all 10 cases showed a male predominance (8:2) with a mean age of 58 years (31-73 years). All 10 cases involved the pleura. Three of 10 patients had known asbestos exposure. Six of 10 patients died of disease at 2-20 months after the diagnosis (mean, 6.9 months). The findings suggest that LHM is a distinct morphological variant of sarcomatoid mesothelioma for which mesothelial differentiation is difficult to document. Many of the cells composing these tumors exhibit fibrohistiocytic differentiation. The unusual morphological pattern of LHM makes a combined modality approach, including IHC, EM, and a knowledge of the clinical/radiologic findings, essential in achieving a correct diagnosis.     

Ten cases of feline mesothelioma: an immunohistochemical and ultrastructural study

In the cat only 10 cases of mesothelioma, mainly of the peritoneum, have been previously reported. This paper describes a further 10 cases, eight pleural and two peritoneal, in males and females aged 1-17 years. Histologically, five tumours were epithelial, three fibrosarcomatous and two biphasic. Immunohistochemical markers used in human pathology for the identification of mesotheliomas include vimentin, cytokeratin (CK) AE1/AE3, HBME-1, CK 5/6, calretinin, thrombomodulin, carcinoembryonic antigen (CEA), CD15, E-cadherin and desmin. All 10 feline mesotheliomas were positive for vimentin and CK AE1/AE3, six were positive for HBME-1, two for CK5/6, three for CEA and four for E-cadherin. All were negative for desmin and calretinin. Antibodies to thrombomodulin and CD15 failed to cross-react with feline tissues. Electron microscopy, performed in four cases, revealed microvillar structures, desmosomes and intracytoplasmic lumina, confirming its value as a diagnostic tool. The study showed that mesothelial marker antibodies commonly used in human patients can be used for the diagnosis of feline mesothelioma, preferably as a panel of antibodies rather than only one.     

Benign papillary mesothelioma of peritoneum: a histological, histochemical and ultrastructural study of six cases

Six cases of localized benign papillary mesothelioma of peritoneum were retrieved from laboratory files over a 20-year period. One presented because of pain following torsion and the remaining five were incidental findings at operation. Light microscopy showed a delicate papillary stroma covered by a single layer of mesothelial cells. The mesothelial cells often showed punctate periodic acid-Schiff staining of cytoplasm. The brush border and stroma showed alcian blue positive staining which was abrogated by prior incubation with hyaluronidase. Electron microscopy revealed typical features of mesothelial cells with long microvilli, rough endoplasmic reticulum in relation to mitochondria, bundles of microfilaments, and tight junctions. Between cells there was a series of intercommunicating channels containing occasional lymphocytes and debris. These features are compared with nodular mesothelial hyperplasia, malignant mesothelioma and adenomatoid tumours of the genital tract. The necessity to distinguish benign papillary mesothelioma from metastatic carcinoma is stressed and relies on the recognition of their mesothelial origin.     

Malignant mesothelioma: cytologic diagnosis with histologic, immunohistochemical, and ultrastructural correlation.

The differential diagnoses of malignant mesothelioma in serous effusions include adenocarcinoma and reactive mesothelial cells. While several cytologic features are of predictive value in separating these entities, immunostaining and ultrastructural examination are important adjuncts that increase the diagnostic yield. Many of the cytomorphologic features can be correlated with immunohistochemical and ultrastructural findings. Most important among these is the ultrastructural demonstration of long, often branching microvillous processes in malignant mesothelial cells. Corresponding microvilli can be visualized by immunostaining for epithelial membrane antigen in both cell block preparations from effusions and biopsy specimens, allowing the identification of malignant mesothelioma. In addition, the circumferential distribution of these immunostained microvilli in cells dispersed in stromal connective tissue identifies them as malignant mesothelial cells, corresponding to the ultrastructural appearance of aberrant microvilli, which project through deficiencies in the basal lamina. These microvilli show interdigitation with stromal collagen fibers, a phenomena not observed in adenocarcinoma.     

Pericardial malignant mesothelioma: Case report and discussion of immunohistochemical and histochemical findings

An extremely rare case of malignant mesothelioma of the pdcardium is reported. The tumor appeared to be the Uphasic type of diffuse malignant mesothetioma which presgnt many small to tine lipid droplets in the cytoplasm, particularly that of the epithelial cell, and a positive immunohistochemical reaction with antibodies to low molecular weight cytokeratin (45–50 kDa) in all of the tumor cells. The literature is also reviewed and the presence of lipid droplets and the importance of the immunohistochemical positivity to low molecular weight cytokeratin for differential diagnosis from other malignant tumors, such as invasive adeno-carcinoma or primary sarcoma of the pleura, or soft tissue sarcoma involving the pleura is discussed.     

Neuronal features of oligodendrogliomas--an ultrastructural and immunohistochemical study

AIMS: To assess neuronal differentiation in oligodendrogliomas (ODGs). METHODS AND RESULTS: An electron microscopic and immunohistochemical study of 41 consecutive cases was performed. In all cases, tumour cells with neuritic structures were identified ultrastructurally, including synapses and neurosecretory granules. For the immunohistochemical identification of synaptophysin, monoclonal antibody clones 27G12, Snp88 and SY38 and a polyclonal antibody were compared in optimized protocols on slides from a spectrum of tissues and 16 ODGs. 27G12 gave the best signal-to-noise ratio, while SY38 gave the poorest. When 27G12 was applied on all 41 ODGs, widespread immunoreactivity was obtained in 100%. Among three antibodies to chromogranin compared similarly, clone LK2H10 and a polyclonal antibody gave identical patterns of immunoreactivity, whereas clone DAK-A3 gave weaker reactions. When LK2H10 was applied on all tumours, staining was found in 12 (29%). All tumours but one stained strongly for glial fibrillary acidic protein and all for synapsin I. Fluorescence in situ hybridization analysis showed a concomitant 1p/19q deletion in 12/16 ODGs. CONCLUSIONS: Our study provides evidence for widespread neuronal differentiation in ODGs, suggesting that these tumours may be derived from progenitor cells with limited commitment. Antibody selection and protocol optimization are mandatory for reliable immunohistochemistry results.     

Primary epithelial malignant mesothelioma of the pericardium with deciduoid features: cytohistologic and immunohistochemical study

Malignant mesothelioma with deciduoid features (MMWDF) is a recently characterized morphologic variant of epithelioid malignant mesothelioma, which frequently is misdiagnosed as peritoneal deciduosis or florid mesothelial hyperplasia. We report on the cytological, histological, immunohistochemical, and autopsy findings of a case of MMWDF arising in the pericardium of a 71-yr-old female patient. Cytology showed large, polygonal to round cells with pale to bright, eosinophilic cytoplasm, occasionally showing xantomatous pattern, containing a pleomorphic and vesicular nucleus with a single prominent nucleolus. Autopsy examination showed a neoplasm encasing the heart and great vessels. No other primary neoplasm was found. The histological analysis disclosed the typical features of MMWDF. Immunohistochemistry showed diffuse immunoreactivity for cytokeratin MNF116, HBME-1, and calretinin in the neoplastic cells, as well as focal positivity for epithelial membrane antigen positivity in a brush border-like pattern. All other markers were negative. We would like to stress that pathologists must be aware of the cytological and histological features of this rare variant of epithelioid malignant mesothelioma in order to avoid a misdiagnosis of a benign process or a metastatic malignancy.     

Pleural mesothelioma of epithelial type and pulmonary adenocarcinoma: an ultrastructural and cytochemical comparison

Twelve diffuse pleural mesotheliomas of epithelial type have been compared with 20 intrapulmonary adenocarcinomas. All mesotheliomas were negative for epithelial mucin by diastase periodic acid Schiff staining and for carcinoembryonic antigen by immunoperoxidase staining, whereas 17/20 carcinomas stained for epithelial mucin and 15/20 for carcinoembryonic antigen. Hyaluronidase-sensitive alcian blue positive material was present in 6/10 mesotheliomas and 0/20 carcinomas. Previously described electron microscopic differences were validated, including one which has so far received insufficient emphasis: microvilli making direct contact through basement membrane deficiencies with collagen fibres on the abluminal side of tumour cells were identified in 10/12 mesotheliomas and in 0/20 carcinomas.     

Brenner tumor of the ovary: a correlative histologic, histochemical, immunohistochemical, and ultrastructural investigation

The histologic, histochemical, immunohistochemical, and ultrastructural features of Brenner tumor (BT) were studied. BT was compared with transitional bladder cells, and close similarities between the two tissues were identified. Abundant glycogen in all cellular layers, an alcianophilic/sialomucinic surface mucous coat, and argyrophilic cells characterized both BT and bladder epithelium. Immunohistochemically, chromogranin and neuron-specific enolase reactivity was observed in all cases examined. An additional relevant finding was the presence of serotonin-storing cells in both BT and urothelium. Moreover, carcinoembryonic antigen, epithelial membrane antigen, and keratin reaction were found in BT and urothelium, indicating an additional antigenic similarity. Additionally, malignant Brenner tumor was ultrastructurally found to share many common features with the bladder tissue. The distinct histochemical, ultrastructural, and antigenic pattern of BT, primarily of the transitional type, is emphasized.     

Well-differentiated papillary mesothelioma of the tunica vaginalis: A case report with aspirate cytologic,immunohistochemical, and ultrastructural studies

A case of a well-differentiated papillary mesothelioma of the tunica vaginalis testis in a 70-year-old man, who presented with a 1-month history of scrotal swelling with hydrocele, is described. Fine needle aspiration cytology of the hydrocele demonstrated a papillary cluster of uniform round cells with minimal atypia, reminiscent of mesothelial cells. Macroscopically, the lesion was characterized by a solitary, well-circumscribed papillary soft tumor measuring 1.2×1.2×1.0 cm³. Histologically, the tumor exhibited papillary or tubulopapillary proliferation of predominantly bland cuboidal cells. No cellular pleomorphism, mitotic figures, necrosis, or stromal invasion was noted. Immunohistochemically, the tumor was positive for CAM5.2, epithelial membrane antigen, vimentin, calretinin, and D2-40, but negative for carcinoembryonic antigen. Ki-67 index was less than 1%. Ultrastructurally, the tumor cells showed numerous microvilli, mitochondria, rough endoplasmic reticulum, microfilaments, and desmosomes. The patient is alive with no evidence of disease at 18 months after right radical orchiectomy. Ki67 may be potentially a good maker for differentiating low-grade from high-grade mesothelioma.     

The effect of immobilization on myotendinous junction: an ultrastructural,histochemical and immunohistochemical study

Kannus , P., Jozsa , L., Kvist , M., Lehto , M. & Järvinen , M. 1992. The effect of immobilization on myotendinous junction: an ultrastructural, histochemical and immunohistochemical study. Acta Physiol Scand 144 , 387–394. Received 28 April 1 991 , accepted 13 October 1991. ISSN 0001–6772. Tampere Research Station of Sports Medicine, UKK-Institute, and Department of Surgery, Tampere University Central Hospital, Tampere, Finland; Department of Morphology, National Institute of Traumatology, Budapest, Hungary; and Sports Medical Research Unit, Paavo Nurmi Center, University of Turku, Turku, Finland. The effect of immobilization on the myotendinous junction of the calf muscles in the rat was studied histochemically, immunohistochemically and morphometrically with a transmission electron microscope. After 3 weeks of immobilization, the contact area between the muscle cells and tendineal collagen fibres was reduced by almost 50% in both type I (slow-twitch) and type II (fast-twitch) muscle fibres. The terminal finger-like processes of the muscle cells became shallow and cylindrical or were completely atrophied. Their basal membranes were slightly thickened. Histochemically, the most remarkable alteration in the myotendinous junction was the marked decrease in the sulphate containing glyco-saminoglycans. In the basal lamina of the muscle fibres, the glycosaminoglycan and proteoglycan content was also reduced. Immunohistochemical analyses revealed that the amount of type III collagen was markedly increased on the myotendinous interface, but the amount and distribution of type I collagen was not affected by immobilization. These findings suggest that immobilization causes degenerative changes at the myotendinous junction, which, in turn, most likely decrease its tensile strength and may predispose it to rupture during activity.     

Histological,histochemical, and immunohistochemical studies of hippocampus in male New Zealand rabbits

The present study aims to give detailed histomorphological features of the hippocampus of adult male New Zealand rabbits. Both histological and histochemical specimens were prepared to be examined microscopically by using a light microscope. The hippocampus appeared as C-shaped hippocampal proper, dentate gyrus, and subiculum. The hippocampal proper subdivided along its length according to the density and size of its major constituent pyramidal cells into four distinct regions named Cornu Ammonis (CA1, CA2, CA3, and CA4). With the histochemical preparations, each of these regions consisted of five layers, stratum alveolus, stratum oriens, stratum pyramidale, stratum radiatum, and stratum lacunosum-moleculare. The stratum pyramidale constituted the middle dark zone and contained the principal excitatory neurons and a few interneurons. Histochemically, the pyramidal neurons along all regions of the CA reacted positively to Grimelius silver impregnation, lead hematoxylin, Gomori's aldehyde fuchsin, aldehyde thionine, Gomori's chrome alum hematoxylin, and performic acid alcian blue stains. Immunohistochemically, the pyramidal neurons reacted positively to anti-NSE antibodies. The dentate gyrus was formed of three distinct layers. The subiculum was formed of proper subiculum, presubiculum, and parasubiculum.     

Intervertebral disc amyloidosis: histochemical, immunohistochemical and ultrastructural observations

Intervertebral discs selected at random from autopsies and surgical operations on herniated discs were examined for evidence of amyloid deposition. Amyloid deposits were detected in 53 (81.5%) of 65 autopsy cases. Discs from subjects over 50 years of age revealed a significantly high incidence of amyloid deposition. Among herniated discs, amyloid deposits were documented in 49 (75.4%) of 65 surgical specimens. The incidence of amyloid deposition in intervertebral discs increased with advancing age. Intervertebral disc amyloidosis consisted of amyloid deposits of three morphological types: linear amyloid deposits around the degenerating chondrocytes (perichondrocyte type), and nodular or band-like deposits in the annulus fibrosus (annulus fibrosus type) and nucleus pulposus (nucleus pulposus type). We suspect that the precursor protein of perichondrocyte type amyloid is derived from chondrocytes, and those of annulus fibrosus type and nucleus pulposus types are derived from the blood. The amyloid deposits were resistant to treatment with potassium permanganate. Immunohistochemically, the amyloid deposits reacted with antibody against amyloid P-component, but not with antibodies against AA, A k , Aλ, transthyretin or β₂-microglobulin. Ultrastructurally, the amyloid deposits were composed of 10 nm-wide nonbranching fibrils. The amyloid in herniated discs had the same biochemical and immunohistochemical properties as those found in autopsy cases. The immunohistochemical characteristics of the amyloid deposits suggest that it derives from an, as yet, unknown precursor protein.     

Malignant biphasic peritoneal mesothelioma in a child: Fine-needle aspiration cytology, Histopathology, and immunohistochemical features along with review of literature

Peritoneal mesotheliomas in children are of rare occurrance. We herein report the clinical, radiological, and pathological findings of a rare case of malignant peritoneal mesothelioma occurring in nine‐year‐old female child. The child presented with abdominal distension and awareness of a painless mass in the abdomen which on radiology appeared as a large heterogeneous pelvic mass with peritoneal deposits at multiple sites. To the best of our knowledge, this is the first case of a peritoneal malignant mesothelioma on which fine needle aspiration (FNA) was performed as first line investigation of the primary tumor. The cytological features, major differential diagnoses, and the pitfalls therein are discussed. Histopathology revealed biphasic pattern of mesothelioma which is again a rare pattern. Immunochemistry was carried out on the cell block made from the FNA as well as the biopsy specimen essentially showed the same features. There was positivity for vimentin, EMA, and cytokeratin 5/6 while WT1, calretinin, and CEA were negative; however, D2‐40 showed diffuse membranous positivity in the epithelial areas and cytoplasmic positivity in the spindle areas confirming a mesothelioma. We emphasize the use of immunochemistry on cell block material for a confident diagnosis of mesothelioma in such cases. Diagn. Cytopathol. 2012. © 2011 Wiley Periodicals, Inc.     

Gangliocytic paraganglioma of the duodenum: report of cytologic, histologic, immunohistochemical, and ultrastructural features of a case

A case of gangliocytic paraganglioma of the duodenum is reported, including light microscopic, ultrastructural, and immunohistochemical characteristics. The cytologic appearance, as might be seen in fine-needle aspiration smears, indicates a neoplasm with three cellular components (epithelioid, ganglion, and spindle cells) seen histologically by light and electron microscopy.     

Malignant melanoma with neuroendocrine differentiation: clinical, histological, immunohistochemical and ultrastructural features of three cases

AIM: To document the clinical, histological, immunohistochemical and ultrastructural features of three malignant melanomas showing neuroendocrine differentiation. METHODS AND RESULTS: Three patients, two with primary cutaneous melanoma and one with nasal mucosal melanoma, subsequently developing or simultaneously presenting with metastatic malignant melanoma, were studied by conventional histological technique, immunohistochemistry of formalin-fixed paraffin-wax embedded tissues, and electron microscopy of epoxy-resin-embedded tumour tissue. Tumours showed either small cell or conventional malignant melanoma cell morphology. One of the three primary melanocytic lesions (the nasal melanoma) exhibited neuroendocrine differentiation immunohistochemically. All three metastatic malignant melanomas showed, in varying combinations, immunohistochemical and ultrastructural evidence for neuroendocrine differentiation: they were positive for the melanocytic markers, S100 protein, HMB-45, Melan-A and tyrosinase, and the neuroendocrine markers chromogranin, synaptophysin and neurofilament protein. Ultrastructural study in two of the metastases revealed neuroendocrine granules but no lattice-bearing melanosomes. CONCLUSIONS: The cases described are the most comprehensively investigated malignant melanomas showing neuroendocrine differentiation to date, and the first to document neuroendocrine differentiation ultrastructurally in these tumours. Malignant melanoma with neuroendocrine differentiation therefore needs to be recognized among the other, better known variants of malignant melanoma.     

Paragangliomas: assessment of prognosis by histologic, immunohistochemical, and ultrastructural techniques

To predict clinical outcome, we studied 42 paragangliomas from 37 patients by routine histology, immunohistochemistry, and electron microscopy. A panel of antisera to neuron-specific enolase (NSE), chromogranin, and met-enkephalin was used to identify chief (type I) cells, and S-100 protein and glial fibrillary acid protein (GFAP) sustentacular (type II) cells. The intensity of staining of type I cells and the density of type II cells were assessed semiquantitatively (0 to 4+) in a total of 38 tumors. A total of 23 of 24 low-grade tumors (solitary, multiple, or associated with other neoplasms; 95.8%) contained type II cells immunoreactive with either S-100 protein or GFAP, and all were positive when S-100 protein and GFAP were used in combination. Five of the nine intermediate-grade (recurrent and/or locally aggressive) tumors were identified as glomus jugulare tumors (GJT). Three intermediate-grade GJTs were devoid of GFAP-reactive type II cells and four GJTs were negative for S-100 protein. Type II cells were identified in only one of five high-grade (malignant) paragangliomas and that tumor contained vanishingly rare cells that were weakly S-100 protein positive but GFAP negative. Sustentacular cell density and chief cell staining intensity were both inversely related to tumor grade. The most sensitive chief cell marker was NSE (92.1%), followed by chromogranin (84.2%). The least sensitive (73.0%) and specific marker was met-enkephalin. Combinations of NSE or chromogranin with met-enkephalin identified chief cells in all cases. Electron microscopy identified neurosecretory granule-containing chief cells, but was of less value in delineating sustentacular cells because of their scarcity and the absence of specific features. By comparison, immunohistochemistry was superior in identifying sustentacular cells. The use of an immunohistochemical panel, in addition to routine histology, can confirm the diagnosis of a paraganglioma and can give an indication of the likely prognosis for a patient.