Use of basement membrane markers in tumour diagnosis

Defining invasion in breast cancer: the role of basement membrane

Basement membrane (BM) is an amorphous, sheet-like structure separating the epithelium from the stroma. BM is characterised by a complex structure comprising collagenous and non-collagenous proteoglycans and glycoproteins. In the breast, the thickness, density and composition of the BM around the ductal lobular system vary during differing development stages. In pathological conditions, the BM provides a physical barrier that separates proliferating intraductal epithelial cells from the surrounding stroma, and its absence or breach in malignant lesions is a hallmark of invasion and metastases. Currently, diagnostic services often use special stains and immunohistochemistry (IHC) to identify the BM in order to distinguish in situ from invasive lesions. However, distinguishing BM on stained sections, and differentiating the native BM from the reactive capsule or BM-like material surrounding some invasive malignant breast tumours is challenging. Although diagnostic use of the BM is being replaced by myoepithelial cell IHC markers, BM is considered by many to be a useful marker to distinguish in situ from invasive lesions in ambiguous cases. In this review, the structure, function and biological and clinical significance of the BM are discussed in relation to the various breast lesions with emphasis on how to distinguish the native BM from alternative pathological tissue mimicking its histology.

Evaluation of EGFR in prognostic characterization in histopathological variants of oral squamous cell carcinoma

AIM OF THE STUDY

Epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor of the Erb B family contributing to proliferation, invasion, and metastasis. EGFR overexpression is frequently associated with poor clinical outcome in malignant neoplasms.• To evaluate and compare immunoexpression of EGFR in histopathological variants of oral squamous cell carcinoma (OSCC).• To hypothesize the role of EGFR in determining biological behavior and prognostic course of histopathological variants of OSCC.

MATERIALS AND METHODS

The study comprised a total of 40 cases including 10 cases each of Squamous cell carcinoma, Verrucous carcinoma, Adenosquamous cell carcinoma, and Adenoid squamous cell carcinoma. EGFR immunoexpression was observed qualitatively as low (1), moderate (2) and strong (3) and quantitatively as score 1 for <10%, 2 for 10%-50%, and 3 for >50% positive cells. The resulting data were analyzed using SPSS software version 19. Data have been expressed as mean and standard deviation. Differences between the different variables were analyzed using ANOVA, and Pearson's Chi-square. (p ≤ 0.05).

RESULT

The study results revealed that the EFGR immunoexpression was highest in adenosquamous cell carcinoma followed by adenoid squamous cell carcinoma then conventional squamous cell carcinoma followed by lowest immunoexpression in verrucous carcinoma. The results were statistically significant. (p ≤ 0.05).

CONCLUSION

Expression of EGFR could be established as a valuable biomarker with significant association in predicting aggressive potential and treatment response in various histopathological variants of OSCC. Further studies where EGFR could be linked to predictive indicators and tumor prognosis could be undertaken.

Immunohistochemical Distribution of Basement Membrane Type IV Collagen and Laminin in Synovial Sarcoma

Aims

To investigate the distribution of basement membrane components type IV collagen and laminin in synovial sarcomas.

Methods

Paraffin sections from four synovial sarcomas were studied by the peroxidase-antiperoxldase procedure using specific antibodies to type IV collagen and laminin.

Results

Type IV collagen and laminin immunoreactivity was confined around epithelial areas in biphasic tumors. Several interruptions and discontinuities of the linear basement membrane profile were seen in sites of transition between mesenchymal and epithelial tissue. Moreover, a spot-like immunoreactivity was often observed in the spindle cell component of biphasic tumors. Monophasic tumors were either negative or showed a pericellular staining for both type IV collagen and laminin.

Conclusions

The distribution of basement membrane components is clearly related to the formation of epithelial elements in biphasic synovial sarcoma. The spot-like immunoreactivity of the spindle cell component, and the basement membrane interruptions at the boundary between mesenchymal and epithelial tissue, are both consistent with early basement membrane formation by developing epithelium. These findings support the concept that synovial sarcomas are basically soft tissue carcinosarcomas and that the epithelial component of the tumors develops by conversion of mesenchyme to epithelium.

Superficial and early cancers of the esophagus

The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on the evolution of Barrett's dysplasia to early cancer; the early detection of esophageal cancer in China; new technologies of treatment for dysplasia; the prognostic value of molecular markers expression in esophageal squamous cell carcinoma; the follow-up schedule after ablation of high-grade dysplasia; intramucosal cancers; and tubular widespread endoscopic esophageal submucosal dissection with high-dose steroid stricture prevention.

Immunohistochemical expression of basement membrane proteins of verrucous carcinoma of the oral mucosa

Squamous cell carcinoma (SCC) of the oral cavity is an extremely invasive tumour of stratified squamous epithelium that spreads throughout degradation of the basement membrane (BM) and extra-cellular matrix. Oral verrucous carcinoma (VC) is a rare low-grade variant of oral SCC that penetrates into the subepithelial connective tissue. It also has a different clinical behaviour from classical oral SCC. We investigated the immunohistochemical expression of laminin, laminin-5, collagen IV and fibronectin in VC, severe epithelial dysplasia (SED) and SCC in order to analyse if the pattern of these molecules expression contributes to the differences in the biological behaviour of these diseases. The staining pattern of laminin was less intensive in SCC compared with SED and VC, and collagen IV expression was increased in VC compared with SED. Discontinuities of laminin, collagen IV and fibronectin were more evident in SED than in VC. This study indicates that VC has a biological behaviour different from SED or SCC, observable by immunohistochemistry in the BM zone.

Alterations of the vascular basal lamina in the cerebral cortex in drug abuse: a combined morphometric and immunohistochemical investigation

In drug abusers, white matter hyperintensities, perfusion deficits, and metabolic disturbances are detected by neuroimaging analyses in different brain regions. A specific pattern of involvement or a predominance of a specific brain region cannot be drawn. To examine changes of the cerebral microvasculature as a possible morphological substrate of the neuroimaging findings, brain specimens of 12 polydrug abusers and 8 controls were obtained at autopsy. The basal lamina of blood vessels from the frontal, temporal, parietal, and occipital lobes was analysed by means of immunohistochemistry for collagen type IV. The numerical density of vessels was determined in the gray and white matter, and their staining intensity was rated using a three-point scale. In the gray and white matter of polydrug abusers, the number of vessels showing strong immunoreactivity for collagen type IV was significantly reduced, whereas the number of vessels with mild and moderate immunoreactivity was increased as compared to controls. The total numerical density of vessels was not significantly changed. Our results show a significant reduction in immunoreactivity for collagen type IV in the brains from polydrug abusers compared to controls, which may be due to a thinning of the basal lamina of cerebral vessels. The data of the present study show morphological changes of the basal lamina in the brain of polydrug abusers, which might represent the morphological substrate of a disturbed blood-brain barrier. However, it remains yet to be established if the observed changes are responsible for the alterations seen in different neuroimaging analyses and which drug might be of major pathogenetic significance.

Immunohistochemical study of equine endometrial extracellular matrix during the oestrous cycle

This study was designed to identify the distribution of type IV collagen, laminin, and fibronectin with an avidin-biotin method in sections of equine endometrial samples, fixed in Bouin's solution and embedded in paraffin wax. Thirty endometrial biopsies were collected at three different stages of the oestrous cycle. The basement membrane of luminal epithelium reacted positively with antibody against type IV collagen. Both type IV collagen and laminin were found in the basement membranes of endometrial glands, and fibronectin occurred diffusely in the interstitial tissue. Blood vessels expressed all of the extracellular matrix components studied. No differences in the distribution of extracellular matrix components were found at the different stages of sampling.

Can alterations in integrin and laminin-5 expression be used as markers of malignancy?

Development of squamous cell carcinomas (SCCs) involves alterations in the adhesive interactions in the epithelium and invasion through the basement membrane. Therefore, changes in the expression of receptors and ligands involved in cell-cell and cell-matrix adhesion may be essential for the transformation of a premalignant into a malignant lesion. The aim of this study was to examine if expression of specific cell adhesion molecules can be used as markers of malignant development. By immunohistochemistry, we examined the expression pattern of integrins alpha2beta1, alpha3beta1, alpha6beta4 and laminin-5 in biopsies from SCCs (n=18), premalignant lesions (leukoplakias, n=21) and non-premalignant tissue with chronic inflammation (n=11). In poorly differentiated SCCs, patchy loss of alpha3beta1, alpha6beta4 and laminin-5 expression was pronounced at the invasion front, whereas there was a tendency to increased expression of alpha2beta1. Analogous to the SCCs, biopsies from the leukoplakias and the non-premalignant inflammatory tissue showed alterations of the expression of alpha3beta1 and alpha6beta4 in the basal cell layers and of laminin-5. However, a characteristic finding in biopsies from leukoplakias was loss of alpha2beta1 and alpha3beta1 in the suprabasal cells. There was no unequivocal expression of the adhesion molecules distinguishing between inflammatory tissue, premalignant, and malignant lesions.

Loss of basement membrane components laminin and type IV collagen parallels the progression of oral epithelial neoplasia

AIMS

To determine the immunohistochemical localization of basement membrane components laminin and type IV collagen in premalignant and malignant lesions of the oral epithelium.

METHODS AND RESULTS

Formalin-fixed tissue sections of 12 epithelial hyperplasias with no dysplasia and 30 dysplasias, clinically diagnosed as leukoplakia and/or erythroplakia, as well as 50 invasive squamous cell carcinomas, were stained with mouse monoclonal antibodies to human laminin and type IV collagen. Statistical analysis showed that there was a linear trend for discontinuous distribution of laminin from epithelial hyperplasia to epithelial dysplasia and invasive squamous cell carcinoma (P < 0.001). Laminin staining showed a linear trend for discontinuity with increasing grade of dysplasia (P < 0.05) and was more frequently discontinuous in areas of deep tumour invasion than in central or superficial areas (P < 0.05). Brush-shaped thickening and reduplication of the basement membrane were also identified.

CONCLUSIONS

Alterations in the distribution of laminin and type IV collagen in oral premalignant and malignant lesions indicate that the loss of continuity of the subepithelial basement membrane parallels the progression of the neoplastic transformation process in oral epithelium.

Molecular variants of fibronectin and laminin: structure, physiological occurrence and histopathological aspects

This review deals with biological and pathological aspects of various isoforms of the matrix molecules fibronectin and laminin. They are generated by different molecular mechanisms: ED-A+ and ED-B+ fibronectin by alternative splicing of pre mRNA, de novo-glycosylated fibronectin by alternative post-translational O-linked glycosylation of the IIICS region, and the laminin isoforms by exchange of single chains of the heterotrimeric molecule. In contrast to the "common" fibronectin, the distribution of ED-B+ and de novo-glycosylated fibronectin is restricted to embryonic tissues; they subsequently reappear in granulation tissue, in fibrosing processes and in tumour stroma. The expression of these so-called oncofetal fibronectins is stimulated by growth factors (TGF beta). The association of the ED-B+ fibronectin with proliferative activity and newly formed vessels identifies this fibronectin variant as a marker of cellular activity in the process of fibrosis and as a suitable agent for the evaluation of tumour angioneogenesis. Initial results suggest a correlation between the amount of ED-B+ and de novo-glycosylated fibronectin in tumour stroma and the behaviour of carcinomas with regard to their invasiveness and propensity for metastatic dissemination. The current nomenclature of the laminin molecule family is presented. The laminin chain constitution of basement membranes switches from embryonic or proliferatively active to adult terminally differentiated tissues [disappearance of the laminin beta 2 (s) chain] and depends on the tissue type. The discrepancy between the loss of basement membranes (multiple basement membrane defects) in carcinomas and the recently reported increased laminin chain synthesis in these tumours may be explained by abundant laminin chain deposition outside the basement membrane in the carcinoma invasion front, possibly associated with enhanced adhesion of budding tumour cells.

Infantile hemangioendothelioma of the liver in a neonate. Immunohistochemical observations

The study documents the immunohistochemical features of a case of infantile hemangioendothelioma (IHE) of the liver, which was found incidentally at autopsy in a 44-day-old girl. A precardial apical systolic murmur and hepatomegaly were found on day 4 of life. The tumor was multifocal and histologically composed of vascular channels lined by endothelial cells that were positive for von Willebrand factor, CD31, vimentin, and Ulex europaeus agglutinin 1, and that were invested in a continuous basement membrane (BM) on the antiluminal border. The endothelial cells, especially in the region of intravascular buds, showed intracytoplasmic synthesis of BM components (laminin and collagen IV). Underlying the endothelial cells were cells with cytoplasm that was positive for alpha-smooth muscle actin and antimuscle actin and negative for desmin, and that were enveloped with BM. The immunophenotype, appearance, and location of these cells are characteristic of pericytes. We found neither signs of endocrine secretion nor hepatitis B virus in the tumor tissue. The appearance of this tumor in the neonatal period supports a fetal origin of IHE.

Abnormalities in type IV collagen immunoreactivity in human laryngeal cancers

Abnormal patterns of expression of the basement membrane type IV collagen are observed in many human cancers. This study examines the immunohistological expression of type IV collagen in the basement membrane in human laryngeal squamous cell carcinomas (SCC) (n = 24). Non-neoplastic vocal cord polyps (n = 4) were used as controls. The formalin-fixed, paraffin-embedded tissues were sectioned and pretreated with protease prior to immunostaining for type IV collagen. There was a statistically significant difference in type IV collagen expression between laryngeal SCC and vocal cord polyps (p = 0.0001; chi 2 test with continuity correction). In laryngeal SCC (n = 24; 100%), type IV collagen distribution was discontinuous and irregular or absent around individual or groups of neoplastic cells. In contrast, all of the cases of vocal cord polyps (n = 4; 100%) displayed a continuous pattern of subepithelial basement membrane type IV collagen. This study has shown that abnormal distribution of type IV collagen occurs in laryngeal squamous cell carcinomas but not in non-neoplastic vocal cord polyps. This may be related to either abnormal synthesis or to the breakdown of the collagen and it may be of use as a potential biological marker in the study of laryngeal carcinogenesis.

Growth pattern of experimental squamous cell carcinoma in rat submandibular glands--an immunohistochemical evaluation

Histopathological and immunohistochemical studies during carcinogenesis in rat submandibular glands (SMGs) using a carcinogen (9,10-dimethyl-1,2-benzanthracene: DMBA) were evaluated. For carcinogenesis, the carcinogen-containing sponge was surgically inserted into the gland. Histopathological features during carcinogenesis were as follows; dilatation of ductal segments, the presence of duct-like structures and cystic lesion around the sponge were observed within 3 weeks of the experiment, squamous metaplasia in duct-like structures and lining epithelium of the cystic structures around the sponge were observed at 4-6 weeks of the experiment, and finally well differentiated squamous cell carcinomas (SCCs) were observed after 8 weeks of the experiment. The immunoreactivity of K8.12 keration (K8.12), S-100 protein (S-100), epidermal growth factor (EGF), laminin, and proliferating cell nuclear antigen (PCNA) were evaluated. In the normal SMG, EGF was confined to the granular cells and S-100 to the pillar cells of granular convoluted tubules (GCTs). K8.12 was found in striated (SD) and excretory duct (ED) cells and laminin showed linear staining of the basement membrane around the ducts, acini and blood vessels. PCNA-positive nuclei were rarely observed in the normal glandular parenchyma. During carcinogenesis, during the first stage, EGF in granular cells and S-100 in pillar cells of GCT segments disappeared, and cytokeration K8.12 was observed in duct-like structures and cystic epithelium around the DMBA sponge. PCNA-positive nuclei in the first stage were mainly confined to basal cells of morphologically altered ducts. During the second stage, squamous metaplastic cells showed an intense K8.12 reaction. During the third stage, the well differentiated SCC showed strong reaction for K8.12, and the linear staining for laminin staining had disappeared at the invading fronts. The PCNA index was nearly 40% in the tumour cell component. The stem cells or the progenitor cells during experimental carcinoma were most likely to be the ductal basal cells, and carcinogenesis was initiated with an increase of proliferating activity in small cell clusters surrounding a necrotic area, basal cells of dilated excretory ducts and duct-like structures. Thus, all ductal segments undergoing squamous metaplasia may participate in the genesis of neoplasia during experimental carcinogenesis.

Immunostains for collagen type IV discriminate between C-cell hyperplasia and microscopic medullary carcinoma in multiple endocrine neoplasia, type 2a

At a light microscopic level, the separation of C-cell hyperplasia and microscopic medullary carcinoma of the thyroid (MCT) is difficult, and it ultimately rests on the finding of C cells outside of the thyroid follicular basement membranes (FBMs). To date, this has required ultrastructural examination for proper documentation. The assessment of thyroidectomy specimens from patients with multiple endocrine neoplasia, type 2a (MEN2a), a hereditary condition in which there is widespread C-cell hyperplasia (CCH) and multifocal MCT, presented an opportunity to the authors to assess the entire range of C-cell abnormalities. Total thyroidectomy specimens from 17 patients with MEN2a were examined. In addition to hematoxylineosin (H&E) stains, representative tissue sections were labeled for chromogranin A and collagen type IV (CIV), using the avidin-biotin-peroxidase complex (ABC) method. All patients in the study had multifocal C-cell proliferation that was both diffuse and nodular. Fifteen had microscopic MCTs, which were multifocal in eight instances. Three patterns of C-cell proliferation were recognized in CIV immunostains. The first was characterized by complete investment of C-cells by a continuous rim of CIV, corresponding to FBM and confirming an intrafollicular localization; hence, the diagnosis of CCH was made in such cases. The second pattern was distinctive and was typified by defects in the CIV layer; constituent C-cells assumed an extrafollicular location. These images yielded a diagnosis of micro-MCT. The latter findings were also accompanied by focal reduplication of basement membrane that was apparently tumor derived, producing a micronodular or microlobular configuration. The third pattern represented a combination of the first two, with C-cell nodules that were bounded by CIV and clearly situated in an intrafollicular location; however, focal reduplication of basement membranes was also evident in these cases. The biological significance of the third pattern of CIV staining is uncertain, but it may reflect the presence of a preinvasive proliferation of C-cells that is distinct from "usual" CCH in MEN2a.

Laminin expression in testicular tumours of the dog

The expression of laminin was studied to determine the distribution pattern of basement membranes (BMs) in normal testes and in a series of 40 canine testicular tumours (seminomas, Leydig and Sertoli cell tumours). BM was always present around seminiferous tubules and blood vessels in normal testes and in seminomas and Sertoli cell tumours of the intratubular type without invasion. BM changes (fragmentation or loss, or both) were usually found in invasive neoplasms which retained their tubular structure; disruption or absence was observed in tumours, with a diffuse pattern. The BM was never expressed in Leydig cell tumours, except around vessels, irrespective of their histological growth pattern (cystic-vascular, pseudoadenomatous, diffuse). An attempt was made to relate the degree of BM modification to proliferative monoclonal antibodies and mitotic index. In parallel with the progressive loss of BM an increase in proliferative activity occurred, indicating that BM changes are additional useful prognostic indicators in testicular tumours of the dog.

The influence of local tissue environment on epithelial basement membrane continuity in colorectal carcinomas

For colorectal carcinomas, there is evidence that marked discontinuity of the epithelial basement membrane (EBM) is associated with higher malignant potential. Since the metastatic process appears to be selective, more discontinuous EBMs might be expected in secondary rather than in primary tumours. To test this prediction, we examined a series of 60 cases of colorectal carcinoma for which samples of lymph-node or liver metastases were available. Sections were immunocytochemically stained for laminin, and the continuity of tumour EBM was then assessed by observational rating as well as by detailed morphometric analysis for a sample of cases. Contrary to the above prediction, we find that EBMs tend to be more continuous in secondary tumours than in corresponding primary tumours. These results could be explained by the possibility that local tissue environmental factors have a major influence on EBM continuity. Supporting evidence comes from our previous observation that EBM is very discontinuous at the advancing edge of primary colorectal carcinomas, where the tumour is adjacent to collagen-I-deficient stroma. Further evidence from the present study is that the EBM is extremely discontinuous at the interface between metastases and specialised parechymal tissue, but more continuous at the interface between metastases and stromal connective tissue. Since basement membranes affect the differentiation and behaviour of adjacent cells, these findings suggest that host tissue may influence invasive activity through their effects on EBM continuity.

Patterns of integrin common chain beta 1 and collagen IV immunoreactivity in hepatocellular carcinoma. Correlations with tumour growth rate, grade and size

Thirty cases of hepatocellular carcinoma (HCC) were investigated immunocytochemically for expression of beta 1 integrin molecule and of collagen IV. Immunoreactivity was related to the tumour proliferation index, as detected by PCNA immunostaining, and to tumour size and grade. Membrane beta 1 integrin immunoreactivity was detected in the neoplastic cells of all cases, though two different staining patterns were clearly recognized. In 14 cases, beta 1 integrin immunoreactivity was confined to the cell-stroma interface, showing the same polarized pattern as the non-neoplastic cell counterpart. This staining pattern was associated significantly (P < 0.0001) with low PCNA labelling (i.e. less than 20 per cent of neoplastic cells showing nuclear immunostaining. Conversely, 16 cases showed non-polarized pericellular beta 1 integrin immunostaining. This staining pattern was significantly associated (P < 0.0001) with high PCNA labelling (more than 20 per cent of immunoreactive cells) and with tumour size greater than 4 cm in diameter (P < 0.0001). beta 1 Integrin, collagen IV, and PCNA immunoreactivities, however, did not correlate with the histological grade. The data emphasize that neoplastic progression of HCCs may be correlated with an aberrant expression of adhesion molecules and with a disruption of the collagen IV complement of basal membranes.

Patterns and composition of basement membranes in colon adenomas and adenocarcinomas

We studied the distribution of type IV collagen and type VII collagen in the basement membranes of normal mucosa of the colon, adenomas, and adenocarcinomas using immunoperoxidase and immunofluorescence techniques. In normal mucosa, we found regular type IV collagen-positive basement membranes, lining vascular structures and mucosal epithelia. These basement membranes, however, lacked type VII collagen. In adenomas of the colon, intact basement membranes were observed through type IV collagen staining. Type VII collagen staining was also detected, but only in connection with dysplastic epithelium. Adjacent to the dysplastic epithelium in adenomas, histologically normal epithelium also showed type VII collagen staining along the basement membrane, but this was restricted to the epithelium of the luminal surface. These areas were also investigated for expression of keratins 8, 18, and 19, and keratins 5 and 8 (monoclonal antibodies NCL-5D3 and RCK 102, respectively), but altered differentiation was not detected using this technique. In adenocarcinomas of the colon, type IV collagen was irregularly deposited in the basement membrane of neoplastic tubules. Type VII collagen staining was detected only in well or moderately differentiated carcinomas and in higher amounts. Our findings therefore reveal a transient expression of type VII collagen in the transition of dysplastic epithelium into carcinoma, suggesting the involvement of type VII collagen in the process of early invasion.

Tissue markers of potentially malignant human oral epithelial lesions

Tissue markers of potential malignancy have been sought for many years. Cell surface markers, particularly blood group and histocompatibility antigens, have shown great promise and several squamous carcinoma antigens have been identified--but not fully studied in potentially malignant lesions. Growth factors and receptors also need further study. Cytoplasmic markers of potential malignancy have been examined and, of these, keratins, filaggrin, and some carcinoma antigens show most promise. Nuclear analyses have promise but are time-consuming and expensive. Image cytometric analyses appear to be sensitive and predictive: oncogene and tumour suppressor analyses remain to be fully evaluated. New investigative techniques at the cellular and molecular level show increasing promise at defining potentially malignant oral epithelial lesions but more prospective studies are required.

Genotypic classification of colorectal adenocarcinoma. Biologic behavior correlates with K-ras-2 mutation type

BACKGROUND

New measures enabling better prediction of biologic behavior of large bowel cancer are highly desirable. One hundred ninety-four consecutive primary, recurrent, and metastatic colorectal adenocarcinomas, accessioned during 1991 at Rhode Island Hospital, were classified according to the presence and specific type of K-ras-2 point mutation.

METHODS

An integrated histopathologic-genetic approach was used to detect mutations starting with minute, topographically selected, tissue samples from formaldehyde-fixed, paraffin-embedded specimens.

RESULTS

Each colorectal adenocarcinoma exhibited either no or only one of seven specific types of K-ras-2 mutation. The mutation type of each primary tumor was present consistently in its metastatic deposits. Thirty-five percent of primary colorectal adenocarcinomas were found to be mutated (42 of 119). A significantly higher mutation rate (65%) was seen in lymphogenous-hematogenous metastases as a group (35 of 54; P < 0.005). By contrast, 22% of anastomotic recurrences and transcoelomic metastasis were mutated (4 of 18). Twenty-eight percent of adenocarcinomas with invasion limited to muscularis propria (Tis, T1, T2) were mutated (16 of 57), compared to 41% for more deeply invasive tumors (T3, T4; 26 of 63). When colorectal adenocarcinomas were analyzed by specific K-ras-2 mutation type, it was found that codon 13 mutated tumors did not progress to local or distant metastasis (P < 0.01). Tumors having a codon 12 valine substitution did not metastasize beyond pericolonic-perirectal lymph nodes. In contrast, colorectal cancers with codon 12 aspartic acid substitutions accounted for most of the distant hematogenous deposits (P < 0.01). Tumors with normal K-ras-2 accounted for most intraperitoneal deposits.

CONCLUSIONS

Genotyping of colorectal adenocarcinoma by K-ras-2 status can identify subsets of patients likely to pursue indolent and aggressive forms of disease. The integrated histopathologic-genetic approach outlined is feasible for use in diagnostic pathology, providing information that together with clinicopathologic staging may individualize and optimize treatment.

Distribution of type-VII collagen in xenografted human carcinomas

The distribution of type-VII collagen, the main molecular component of the anchoring fibrils (AF) attaching the basal lamina (BL, lamina densa of the basement membrane) to the surrounding connective tissue, was investigated in four xenografted human carcinomas of the hypopharynx (H-Stg 1), the lung (L 261), the sigmoid colon (CA 1), and the rectum (R 85). The studies were performed with a recently prepared, affinity-purified and highly specific antibody to type-VII collagen by using the indirect immunofluorescence and the APAAP (alkaline phosphatase anti-alkaline phosphatase) techniques. For comparison, the localization of the intrinsic BL components laminin and type-IV collagen were additionally analyzed in all four carcinomas. It was shown that type-VII collagen usually colocalized to laminin and type-IV collagen and was deposited at the borderline between carcinoma cell clusters and the surrounding strands of connective tissue in a similar, but more diffuse and less continuous distribution than both intrinsic BL components. In the squamous cell carcinoma H-Stg 1 and the adenocarcinoma L261, type-VII collagen was additionally accumulated in enlarged extracellular spaces between carcinoma cells, away from the contact zone to the connective tissue and again colocalized to laminin and type-IV collagen. Numerous carcinoma cells of both xenografts showed remarkable intracytoplasmic immunoreactivity for the antibody to type-VII collagen. Even in the case of the gastrointestinal carcinomas CA 1 and R 85, faint immunoreactivity for type-VII collagen was found at the contact zone between the mucosal epithelium and the surrounding connective tissue. These results confirm that epithelial carcinoma cells are obviously involved with the synthesis of the main molecular component of AF usually attaching the BL to the adjacent connective tissue and hint at a possible correlation between the localization of type-VII collagen and the observed pattern of the BL. However, it cannot be decided whether there is a direct causal relation between both phenomena or whether they are both the consequence of an independent but common cause, such as abnormal cellular differentiation of carcinoma cells. In no case, can the discontinuities in the distribution of type-VII collagen be explained by active tumor cell invasion since xenografted human carcinomas neither invade nor metastasize.

Distribution of extracellular matrix proteins in odontogenic tumours and developing teeth

The distribution of two cellular fibronectins (cFn), tenascin, laminin, as well as type VII collagen was studied in 14 benign odontogenic tumours of epithelial (ameloblastoma) and epithelial-ectomesenchymal (ameloblastic fibroma) origins, as well as in developing human teeth by immunocytochemical means using monoclonal antibodies (Mabs). An extradomain sequence-A-containing form of cFn (EDA-cFn) was seen in the extracellular matrix (ECM) of all tumours studied and in the mesenchyme of the developing tooth germs, indicating that cFn in these tissues are predominantly produced locally. A form of cFn containing an oncofetal domain (Onc-cFn), hitherto found only in carcinomas, was detected focally in the stroma of most ameloblastomas but was absent from ameloblastic fibromas and tooth germs. Tenascin was strongly expressed in the basement membrane (BM) zone of all odontogenic tumours and in that of the early tooth germs. Focal absence of laminin and type VII collagen from the BM of some ameloblastomas and the presence of Onc-cFn in the ECM of most ameloblastomas may correlate with their aggressive behaviour. The results also suggest that EDA-cFn and tenascin are involved in epithelial-mesenchymal interactions during tooth development and in odontogenic tumours.

Thrombospondin and other possible related matrix proteins in malignant and benign breast disease. An immunohistochemical study

Thrombospondin (TSP), which plays an important hemostatic role, is a 450-kd cytoadhesive protein present in the alpha granules of platelets. In vitro experiments using cultured malignant cells suggest that it may help to mediate malignant cell attachment to extracellular matrix and may be important in cancer invasiveness. The authors studied a group of malignant and benign breast tissues for the expression of TSP and provide evidence that TSP may have a role in tumor invasiveness. Using immunohistochemical techniques, the authors found in 48 fresh specimens of breast carcinoma that TSP stained strongly in the desmoplastic stroma or at the basement membrane associated with the malignant ductal epithelium. Tumor cells abutting these tissues revealed cytoplasmic staining for TSP. Stronger TSP staining was seen in the poorly differentiated tumors. These findings were compared with those of normal and benign breast tissue, which showed no TSP staining apart from reactivity in the large distended cysts of fibrocystic disease and faint staining in the stroma of fibroadenomas. Staining for integrin was positive in lymphocytes of both malignant and benign breast disease and equivocally also in the stromal cells of the breast cancer tissue. Immunoreactivity to TSP in tissues was also compared with that of fibronectin, laminin, and collagen type I, III, and IV. The overall findings suggest that thrombospondin may have a role in the tumor biology of invasiveness.

Distribution of type IV collagen immunoreactivity to assess questionable early stromal invasion

AIMS

To determine if the immunocytochemical delineation of subepithelial basement membrane can be used in the assessment of questionable early invasive cervical carcinoma.

METHODS

The distribution of immunoreactive type IV collagen was examined in 15 cervical biopsy specimens in which the reporting pathologist had specifically described difficulty in assessing or excluding early invasion of subepithelial stroma associated with cervical intraepithelial neoplasia (CIN). The results were compared with those from biopsy specimens showing CIN III (N = 8), carcinoma with definite early stromal infiltration (FIGO stage 1a1) (n = 6), and more advanced invasive squamous tumours (FIGO stages 1a2 to 3) (n = 8). In all cases the immunocytochemical findings were assessed in relation to serial sections stained with haematoxylin and eosin.

RESULTS

Six of the 15 diagnostically problematic biopsy specimens were considered, on review, to show early infiltration of subepithelial tissue and putative invasive foci were consistently absent in basement membrane. A similar pattern was observed in the "definite" early invasive cases. Eight problematic biopsy specimens were considered to show only in situ neoplasia; five of these had intact though occasionally attenuated basement membrane, three showed focal type IV collagen defects. In the remaining case biopsy trauma precluded further assessment. Basement membrane defects were identified in five of eight cases of CIN III, while three of eight squamous carcinomas showed partial retention of type IV collagen immunoreactivity around invasive tumour cell nests.

CONCLUSIONS

Defects in subepithelial basement membrane occur in in situ and invasive neoplasia in the uterine cervix. Immunocytochemical staining for type IV collagen is of limited diagnostic value in the assessment of biopsy specimens with questionable early stromal invasion.

Development of the basal lamina in xenografted human carcinomas: an ultrastructural and immunohistochemical study

The development of the basal lamina (BL), the key structure of the basement membrane (BM), was investigated in three xenografted human carcinomas of the sigmoid colon (CA 1), the lung (L 261), and the hypopharynx (H-Stg 1) following heterotransplantation to athymic mice. The study involved the use of electron microscopy and indirect immunofluorescence techniques employing highly specific antibodies against the intrinsic BL components, heparan sulfate proteoglycan, laminin and type-IV collagen. Following transplantation, the extracellular matrix material of the transplanted tumors decomposed and was phagocytozed by invading macrophages within 1 to 2 days. During this stage, no specific binding of the applied antibodies to BL components could be detected within the xenografts. Following the ingrowth of host-derived connective tissue between days 2 to 6, small fluorescence-positive granules appeared within the cytoplasm and around those tumor cells that were located close to the invaded strands of connective tissue. Ultrastructurally, typical secretory granules were detectable in the cytoplasm of many xenografted carcinoma cells. Thereafter, a tannic acid-positive, patchy material appeared in the extracellular space of CA 1 and L 261 and aggregated to form small fragments of a discontinuous BL. In the H-Stg 1 xenografts, this material assembled to form continuous mono-, bi- and multi-layered structures. Large amounts of excess BL material remained accumulated in the L 261 and H-Stg 1 xenografts until the end of the observation period (day 24). These findings reveal that discontinuities of the BL occur independent of the active invasion processes of tumor cells, since xenografted human carcinomas neither grow invasively nor metastasize in nude mice. Moreover, they confirm that these discontinuities are not caused by a quantitatively insufficient production of BL material, but rather arise from qualitative imbalances of the composition of the synthesized BL material.

How malignant is malignant? A brief review of the microscopic assessment of human neoplasms, and the prediction of whether they will metastasize and kill

This review examines ways in which histopathologists can attempt to predict the degree of malignancy from the microscopic examination of surgically removed samples of human neoplasms. These include mitotic counts, measurement of DNA content, analysis of DNA turnover, measurement of proliferation antigens, measurement of nucleolar organizing areas, counting nucleoli, morphometry of nuclei, identification of genetic change, measurement of lysis of basement membrane, and measurement of invasion in vitro. The latter two are not currently of practical value. Of the rest none is uniformly capable of predicting the degree of malignancy of a human neoplasm. After further refinement and control measurement of several such parameters may however contribute more to the prediction of malignancy than present subjective assessments.

The value of immunohistochemistry for collagen IV expression in colorectal carcinomas

The Dukes' classification has well-established prognostic value in colorectal cancer patients. Yet, in each Dukes' class, the survival of individual patients may vary considerably. Recent studies show prognostic significance of genetic alterations in colorectal carcinoma. However, the importance of tumor stromal components noted in the surrounding tissue may have been overlooked by the methods used. Therefore, in a longitudinal study of 154 patients with colorectal cancer operated on between 1967 and 1974, the authors determined the influence on prognosis of lymphocytic infiltration and expression of collagen type IV in tumor stroma. Also, age, sex, Dukes' classification, grade of tumor differentiation, vasoinvasion, and the number of positive lymph nodes were analyzed. Follow-up was at least 15 years. Lymphocytic infiltration and collagen IV expression were scored as mild, moderate, or severe. Survival was analyzed by a Cox proportional-hazards model. The density of lymphocytic invasion showed no significant influence on survival. Collagen IV expression analyzed as a single variable was significantly (P = 0.038) related to better prognosis in colorectal cancer patients. By multi-variate analysis collagen IV expression showed a trend toward better prognosis that was not statistically significant (P = 0.12). Dukes' classification (P less than 0.001), the presence of vasoinvasion (P = 0.009), and lymph node status (P = 0.04) significantly influenced survival. In conclusion immunohistochemistry for collagen IV is an important additional staining technique with prognostic value. In addition, collagen IV immunostaining facilitates recognition of vascular invasion by highlighting the basement membrane of vessels.

The value of immunohistochemistry for collagen IV expression in colorectal carcinomas

The Dukes' classification has well-established prognostic value in colorectal cancer patients. Yet, in each Dukes' class, the survival of individual patients may vary considerably. Recent studies show prognostic significance of genetic alterations in colorectal carcinoma. However, the importance of tumor stromal components noted in the surrounding tissue may have been overlooked by the methods used. Therefore, in a longitudinal study of 154 patients with colorectal cancer operated on between 1967 and 1974, the authors determined the influence on prognosis of lymphocytic infiltration and expression of collagen type IV in tumor stroma. Also, age, sex, Dukes' classification, grade of tumor differentiation, vasoinvasion, and the number of positive lymph nodes were analyzed. Follow-up was at least 15 years. Lymphocytic infiltration and collagen IV expression were scored as mild, moderate, or severe. Survival was analyzed by a Cox proportional-hazards model. The density of lymphocytic invasion showed no significant influence on survival. Collagen IV expression analyzed as a single variable was significantly (P = 0.038) related to better prognosis in colorectal cancer patients. By multi-variate analysis collagen IV expression showed a trend toward better prognosis that was not statistically significant (P = 0.12). Dukes' classification (P less than 0.001), the presence of vasoinvasion (P = 0.009), and lymph node status (P = 0.04) significantly influenced survival. In conclusion immunohistochemistry for collagen IV is an important additional staining technique with prognostic value. In addition, collagen IV immunostaining facilitates recognition of vascular invasion by highlighting the basement membrane of vessels.

Spherical connective tissue inclusions in epithelial hyperplasia of the breast ("collagenous spherulosis")

Partial myoepithelial differentiation is common in simple epithelial hyperplasia (epitheliosis) of the breast but functional myoepithelial differentiation with basement membrane production is exceedingly rare. A peculiar change of hyaline globules within benign epithelial hyperplasia has been recognised before as "collagenous spherulosis" and type IV collagen has been shown by immunohistochemistry. Another seven cases are described which show the presence of laminin and collagens IV and III within the proliferation. Electron microscopy examination of two cases using material retrieved from the wax block showed varying degrees of myoepithelial differentiation of the cells immediately surrounding the spherules and basal lamina material, including mature collagen fibrils in one case. The degree of myoepithelial differentiation of the cells surrounding the spherules seemed to correlate with the differing types and amounts of extracellular matrix in the spherule. Histopathologists should be aware of this rare change as it may be misinterpreted as in situ carcinoma.

A comparison of microwaves and heat alone in the preparation of tissue for electron microscopy

Microwaves have been used to stabilize tissues from the gastrointestinal tract for scanning electron microscopy. The temperature reached is important. Above 55-60 degrees C, epithelial cell sheets begin to lift revealing the underlying basement membrane. These cells may be recovered from the supernatant by micropore filtration or the celloidin sock technique. At higher temperatures, produced either by microwave irradiation or in a water bath, more enterocytes are released. The epithelial cells are larger with increasing temperatures, less with microwaves than with heat alone or in the presence of formaldehyde. At 70 degrees C and above, some proteins are lost and there is false localization of RNA. Some immunoperoxidase reactions are still positive after exposure of the tissue to 60 degrees C. Tissues fixed in boiling formaldehyde retain a surprisingly good morphology.