Use of CD34 in assessing the relationship between stroma and tumor in desmoplastic keratinocytic neoplasms

Polymorphous Adenocarcinoma, Low Grade Variant, Colliding with a Neurofibroma

Collision tumors, composed of two distinct benign or malignant neoplasms, are rarely reported in the oral cavity. We present a case of a 61-year-old female with an asymptomatic non-demarcated lump on the soft palate of unknown duration. An incisional biopsy revealed the presence of two neoplastic populations, a neurofibroma that was partially infiltrated by a polymorphous adenocarcinoma, low-grade variant. Total surgical excision was performed, with uneventful follow-up period. The development of collision tumors may be incidental, although molecular events may influence the pathogenetic mechanism of the phenomenon.

The Multiple Faces of Nodular Trichoblastoma: Review of the Literature with Case Presentation

Trichoblastoma (TB) is a rare biphasic benign adnexal neoplasm originating from follicular germ cells but clinically, it can simulate basal cell carcinoma (BCC), making the diagnosis more difficult. There are several variants of Trichoblastoma and a good knowledge of these is essential for correct diagnosis and management. We report two new cases observed in the last year at our Pathological Anatomy Operative Unit, and conduct a careful review of the literature, from the first description of this lesion by Headington in 1970 to the most recent classifications.

Skin Adnexal Tumors in Plain Language: A Practical Approach for the General Surgical Pathologist

CONTEXT.—

Skin adnexal tumors, those neoplasms deriving from hair follicles and sweat glands, are often a source of confusion amongst even experienced pathologists. Many well-described entities have overlapping features, tumors are often only partially sampled, and many cases do not fit neatly into well-established classification schemes.

OBJECTIVES.—

To simplify categorization of adnexal tumors for the general surgical pathologist and to shed light on many of the diagnostic dilemmas commonly encountered in daily practice. The following review breaks adnexal neoplasms into 3 groups: sebaceous, sweat gland-derived, and follicular.

DATA SOURCES.—

Pathology reference texts and primary literature regarding adnexal tumors.

CONCLUSIONS.—

Review of the clinical and histopathologic features of primary cutaneous adnexal tumors, and the diagnostic dilemmas they create, will assist the general surgical pathologist in diagnosing these often challenging lesions.

CD34 and BerEP4 Are Helpful to Distinguish Basaloid Tricholemmoma From Basal Cell Carcinoma

Tricholemmoma, a benign follicular neoplasm with outer root sheath differentiation, typically comprises clear or pale cells, and when multiple is pathognomic of Cowden's syndrome. The tumor is probably underrecognized and in basaloid examples can be difficult to distinguish from basal cell carcinoma (BCC). We studied 55 tricholemmomas (including 15 basaloid cases) and compared immunohistochemical profile with nodular BCC from our archives. Basaloid and non-basaloid tricholemmomas had similar staining characteristics. BerEP4 was focally positive (range 10%-20%) in only 3/39 (7.7%) tricholemmomas compared with widespread positivity in BCC (90.8%, 139 of 151 cases with ≥50% tumor area stained). CD34 was expressed, usually focally (median 20%, range 10%-90%), in 52/53 (98.1%) tricholemmomas and was negative in all 21 BCCs stained. EMA staining lacked sensitivity or specificity in differentiating tricholemmoma from BCC. Five or more Merkel cells were found in 7/17 (40.1%) tricholemmomas and 1/23 (4.3%) nodular BCCs studied. In summary, immunohistochemistry is helpful in distinction between tricholemmoma, including difficult basaloid examples (BerEP4 negative or focal, CD34 positive) compared with BCC (BerEP4 widespread in most cases, CD34 negative). The presence of 5 or more Merkel cells is a relatively specific but not a particularly sensitive discriminator.

Histologic Mimics of Basal Cell Carcinoma

CONTEXT

- Basal cell carcinoma (BCC) is the most common human malignant neoplasm and is a frequently encountered diagnosis in dermatopathology. Although BCC may be locally destructive, it rarely metastasizes. Many diagnostic entities display morphologic and immunophenotypic overlap with BCC, including nonneoplastic processes, such as follicular induction over dermatofibroma; benign follicular tumors, such as trichoblastoma, trichoepithelioma, or basaloid follicular hamartoma; and malignant tumors, such as sebaceous carcinoma or Merkel cell carcinoma. Thus, misdiagnosis has significant potential to result in overtreatment or undertreatment.

OBJECTIVE

- To review key features distinguishing BCC from histologic mimics, including current evidence regarding immunohistochemical markers useful for that distinction.

DATA SOURCES

- Review of pertinent literature on BCC immunohistochemistry and differential diagnosis.

CONCLUSIONS

- In most cases, BCC can be reliably diagnosed by histopathologic features. Immunohistochemistry may provide useful ancillary data in certain cases. Awareness of potential mimics is critical to avoid misdiagnosis and resulting inappropriate management.

Folliculosebaceous neoplasms: A review of clinical and histological features

Numerous benign and occasionally malignant tumors arise from the folliculosebaceous apparatus. Confusing terminology, rarity of malignant variants and overlapping histological features can lead to diagnostic uncertainty. This review highlights the clinical and histopathological features that help to classify these entities, as well as the various syndromes associated with certain members of this large family of tumors.

Histomorphological and Immunohistochemical Reappraisal of Cutaneous Adnexal Tumours: A Hospital Based Study

Background. Diagnosing adnexal tumours of the skin is a challenge due to their wide variety, infrequent occurrence in practice, and confusing morphological picture. Aims and Objectives. The present study aims to observe the spectrum of adnexal tumours at our institute and to evaluate them based on histomorphological, histochemical, and immunohistochemical methods either alone or in combination for proper identification and classification. Materials and Methods. A partly retrospective and partly prospective study was conducted on adnexal skin tumours over a period of 6 years. Relevant clinical profile was recorded. Histopathological examination was carried out and special stains were applied as and when required. Immunohistochemistry was performed where diagnosis with routine stains was not possible. Results. A total of 150 skin tumour biopsies were received. There were 87 keratotic tumours, 39 adnexal tumours, and 24 melanocytic tumours. Amongst the adnexal tumours, 51.3% eccrine, 30.8% follicular, and 17.9% sebaceous tumours were seen. In five cases, histological diagnosis was troublesome where immunohistochemistry helped in making final diagnosis. Limitations. The sample size is small. Conclusion. Histomorphology is confirmatory in majority of the adnexal tumours but few rare lesions that mimic internal malignancy require a panel of immunomarkers to rule out other possible differentials.

Immunohistochemistry in dermatopathology

CONTEXT

Immunohistochemistry is not a diagnostic test but a highly valuable tool that requires interpretation within a context.

OBJECTIVE

To review the current status and limitations of immunohistochemistry in dermatopathology.

DATA SOURCES

English-language literature published between 1980 and 2014.

CONCLUSIONS

Although immunohistochemistry is rarely completely specific or sensitive, it is an important adjunctive technique in dermatopathology and can be helpful in a series of diagnostic dilemmas.

Desmoplastic trichoepithelioma: report of a unique periocular case

In a 58-year-old woman with blepharospasm, a slowly enlarging left inferomedial eyelid lesion developed. It measured 3 × 5 mm and was nonulcerated, well-circumscribed, whitish, upraised, and firm. An initial incomplete excision followed by a total repeated excision revealed small squamous microcysts, often exhibiting calcifications and cords of nonclefting basaloid cells embedded in a scirrhous stroma characteristic of desmoplastic trichoepithelioma (DTE). Immunohistochemical investigations disclosed CD34-positive stromal fibroblasts and many CK20-positive Merkel cells located among the epithelial cells, features absent in mimicking sclerosing basal cell carcinoma (BCC). The tumor has not recurred during 6 months of follow up. Besides BCC, the differential diagnosis chiefly concerns syringoma and microcystic adnexal carcinoma. Surgical therapy should aim at complete excision but does not have to be as extensive or aggressive as that used for morpheic or sclerosing BCC because of its lack of diffusely infiltrating margins.

Basal cell carcinoma: cell of origin, cancer stem cell hypothesis and stem cell markers

Cancer stem cells have recently been described in several high-grade neoplasms. It is still unclear if they also occur in cutaneous malignancies. Cancer stem cells are not identical with somatic stem cells. The presence of tumour stem cells in a neoplasm does not in itself equal that the tumour derives from a somatic stem cell. A cell originally lacking stem cell characteristics could also acquire those features during the course of carcinogenesis and then becomes the clonal founder cell of a tumour. Basal cell carcinoma (BCC) is the most common cutaneous malignancy. A plethora of various stem cell markers has been applied to study its cellular origin. Intriguingly, the anatomical origin of BCC is still uncertain. This review will discuss the various stem cell markers used in BCC and the cellular origin of this tumour, and touches briefly on the possibility of cancer stem cells in BCC. If BCC or other skin cancers harbour tumour stem cells, these cells could be specifically targeted, making use of specific cell surface molecules such as receptor proteins. Novel drugs directed against those receptor proteins could replace currently available shotgun approaches including imiquimod.

Fibroblast-activation protein: a single marker that confidently differentiates morpheaform/infiltrative basal cell carcinoma from desmoplastic trichoepithelioma

Microscopically, differentiating desmoplastic trichoepithelioma from morpheaform/infiltrative basal cell carcinoma can be difficult as both show 'islands and strands of basaloid cells embedded in a sclerotic stroma'. A superficial shave biopsy further compounds the diagnostic conundrum. Although a plethora of immunohistochemical markers have been touted as being of use as adjunct histologic tools, none thus far appears to be consistent and reliable in terms of specificity and/or sensitivity. Fibroblast-activation protein, a type II membrane-bound glycoprotein belonging to the serine protease family, is expressed in the granulation tissue of healing wounds. More recently, it has been identified as a marker of reactive tumor stromal fibroblasts, as it is reportedly selectively expressed in peritumoral stromal fibroblasts of multiple epithelial cancers including cutaneous malignancies such as basal cell carcinoma. Given this, we sought to ascertain the use of fibroblast-activation protein in distinguishing morpheaform/infiltrative basal cell carcinoma from desmoplastic trichoepithelioma. Immunohistochemical staining for fibroblast-activation protein was performed on desmoplastic trichoepithelioma (n=25) and morpheaform/infiltrative basal cell carcinoma (n=25), with the control group comprising scars from reexcision specimens (n=10). As expected, fibroblast-activation protein expression was observed in stromal fibroblasts of all control cases (10 of 10, 100%). Of interest, fibroblast-activation protein expression was observed in peritumoral fibroblasts of all cases of morpheaform/infiltrative basal cell carcinoma (25 of 25, 100%) but not in any cases of desmoplastic trichoepithelioma (0 of 25, 0%). A gradient of fibroblast-activation protein expression was observed in morpheaform/infiltrative basal cell carcinoma with more intense expression noted in fibroblasts abutting the tumor cells, a less intense expression in the distal peritumoral stromal portion, and minimal to loss of expression in adjacent normal tissue. In summary, findings from this study underscore the use of fibroblast-activation protein as a histologic adjunct in confidently differentiating morpheaform/infiltrative basal cell carcinoma from desmoplastic trichoepithelioma.

Bcl-2 and CD10 expression in the differential diagnosis of trichoblastoma, basal cell carcinoma, and basal cell carcinoma with follicular differentiation

BACKGROUND

Both trichoblastoma and basal cell carcinoma (BCC) of the skin are characterized morphologically by the proliferation of basaloid cells; however, BCCs are clinically associated with a more aggressive behavior. An accurate diagnosis of these lesions is essential for effective, timely treatment and appropriate therapeutic decisions.

METHODS

This study includes 40 lesions. Bcl-2 and CD10 immunohistochemistry were performed in all cases and the patterns of expression were analyzed.

RESULTS

Bcl-2 is useful for the detection of BCC with diffuse expression in nests of basaloid cells, but cannot distinguish between BCC with follicular differentiation and trichoblastoma, as both lesions show the same pattern with positive and negative areas. Conversely, CD10 expression can distinguish between trichoblastomas with peritumoral stromal staining and BCCs with epithelial staining. If both stromal and epithelial areas are stained, these cases are classified as BCC with follicular differentiation.

CONCLUSIONS

CD10 is useful for distinguishing between BCC with widespread follicular differentiation and trichoblastomas.

Current progress of immunostains in Mohs micrographic surgery: a review

Mohs micrographic surgery is often considered the treatment of choice for a variety of skin malignancies. In recent years, the application of immunostaining techniques has facilitated the successful removal of a number of common and less common cutaneous malignancies, including basal cell carcinoma, squamous cell carcinoma, malignant melanoma, dermatofibrosarcoma protuberans, microcystic adnexal carcinoma, sebaceous carcinoma, atypical fibroxanthoma, extramammary Paget's disease, and even sarcomas. Immunostains highlight the tumor cells and allow the Mohs surgeons to pinpoint and eliminate the residual tumor at the surgical margin. It is especially helpful when a tumor presents with subtle or nonspecific histologic features or when a tumor is masked in a pocket of dense inflammation. However, the cost, the labor, and the time consumption are of concern to many of our peers, as are the diversity of antigens, which may overwhelm some. This article serves as a review of the literature on current uses of immunostaining in Mohs micrographic surgery and as a summary of their realistic applications in the dermatologic surgeon's practice. We conclude that immunohistochemical technique has played an important role in Mohs surgery advancement. With greater use and more cost-effective staining methods, we believe that the use of immunostains in a Mohs practice will become routine.

Microcystic adnexal carcinoma: an immunohistochemical reappraisal

Even though immunohistochemical comparisons of microcystic adnexal carcinoma vs infiltrative basal cell carcinoma and desmoplastic trichoepithelioma exist, they are mostly restricted to the use of a single stain. In addition, a comparison with squamous cell carcinoma has not been reported previously. In this study, we compare the expression of cytokeratin (CK) 15, CK7, CK20, CK903, carcinoembryonic antigen (CEA), CD10, CD15 and BerEP4 in 13 microcystic adnexal carcinoma, eight desmoplastic trichoepithelioma, 10 infiltrative basal cell carcinoma, and eight squamous cell carcinoma of which five exhibited ductal differentiation. We found that the majority of microcystic adnexal carcinoma (92%) and desmoplastic trichoepithelioma (100%) cases expressed CK15 while the infiltrative basal cell carcinoma and squamous cell carcinoma cases were all negative. Forty percent of infiltrative basal cell carcinoma expressed CK7; while only two microcystic adnexal carcinoma cases (15%) and one squamous cell carcinoma with ductal differentiation (12%) expressed CK7 in the remaining three tumor categories. None of the desmoplastic trichoepithelioma expressed CK7. All tumors were strongly positive for CK903. While the neoplastic cells were negative, luminal staining of ductal structures was noted for CK7, CD15 and CEA in some of the microcystic adnexal carcinoma, desmoplastic trichoepithelioma and squamous cell carcinoma with ductal differentiation cases. Sixty percent of infiltrative basal cell carcinoma, 31% of microcystic adnexal carcinoma, and 25% of squamous cell carcinoma express CD10. BerEP4 expression was noted in 38% of microcystic adnexal carcinoma, 57% of desmoplastic trichoepithelioma, 100% of infiltrative basal cell carcinoma, and 38% of squamous cell carcinoma. In conclusion, we found CK15 to be a useful marker in distinguishing microcystic adnexal carcinoma from infiltrative basal cell carcinoma and squamous cell carcinoma with ductal differentiation. Our experience indicates that microcystic adnexal carcinoma and desmoplastic trichoepithelioma have a similar immunohistochemical profile that is, CK15+ and BerEP4+/-; thus, additional studies are needed to separate these two entities.

Skin adnexal neoplasms--part 1: an approach to tumours of the pilosebaceous unit

Skin adnexal neoplasms comprise a wide spectrum of benign and malignant tumours that exhibit morphological differentiation towards one or more types of adnexal structures found in normal skin. Most adnexal neoplasms are relatively uncommonly encountered in routine practice, and pathologists can recognise a limited number of frequently encountered tumours. In this review, the first of two, the normal histology of the skin adnexal structures is reviewed, and the histological features of selected but important benign and malignant tumours and tumour-like lesions of pilosebaceous origin discussed, with emphasis on the diagnostic approach and pitfalls in histological diagnosis.

Spindle cell predominant trichodiscoma: a fibrofolliculoma/trichodiscoma variant considered formerly to be a neurofollicular hamartoma: a clinicopathological and immunohistochemical analysis of 17 cases

Seventeen solitary nasal tumors that fulfilled all diagnostic criteria of so-called neurofollicular hamartoma, apart from distinct S100-positivity, were compared histopathologically and immunohistochemically with seven typical trichodiscomas from a similar clinical setting. Both the S100-negative neurofollicular hamartoma-like tumors and the trichodiscomas expressed an identical CD13-positive/CD34-positive fibrocytic immunophenotype without co-expression of neural/perineural (S100, neurofilament, epithelial membrane antigen), myogenic (desmin, calponin, muscle-specific actin, and alpha-smooth muscle actin), or melanocytic (S100, HMB45, NKI/C3, MelanA) epitopes. Histopathologically, there was striking morphologic overlap between trichodiscoma and S100-negative neurofollicular hamartoma-like tumor, apart from a highly characteristic fascicularly organized cellular fibrocytic stroma in the latter. We conclude that fibrofolliculoma/trichodiscoma and neurofollicular hamartoma-like tumor are morphologic variants of a single hamartomatous entity in which neurofollicular hamartoma-like tumor occupies the cellular pole of the morphologic spectrum. The entity formerly known as neurofollicular hamartoma appears to be nothing but a particularly cellular trichodiscoma with a distinctively organized stroma composed of CD34-positive fibrocytes. We therefore propose the new term spindle cell predominant trichodiscoma (SCPT) for this particular variant of the morphologic fibrofolliculoma/trichodiscoma spectrum.

The role of circulating fibrocytes in fibrosis

Fibrocytes are cells that circulate in the peripheral blood and produce connective tissue proteins such as vimentin and collagens I and III. Fibrocytes are associated with skin lesions, pulmonary fibrosis, and tumors and they contribute to the remodeling response by secreting matrix metalloproteinases. Fibrocytes can further differentiate, and they are a likely source of the contractile myofibroblast that appears in many fibrotic lesions. There is evidence in the skin for a prominent role for fibrocytes in the development of hypertrophic scars and keloids. In asthma or in experimental models of pulmonary fibrosis, fibrocytes have been shown to infiltrate areas of inflammation and tissue damage. Fibrocytes constitute part of the stromal response to tumor invasion, and there is evidence that these cells may be a prognosticator of malignant potential. IL-1, TGF-beta, chemokines, and serum amyloid P modulate the appearance and function of fibrocytes. Fibrocytes themselves produce inflammatory cytokines, growth factors, and chemokines. The intercellular signals that modulate fibrocyte trafficking, proliferation, and differentiation are only partially defined, but a better understanding of these signals enable new therapies to prevent pathologic fibrosis or to improve the tissue repair response.

CD10 expression in trichoepithelioma and basal cell carcinoma

BACKGROUND

Trichoepithelioma (TE) is a benign neoplasm that shares both clinical and histologic features with basal cell carcinoma (BCC). However, it is important to distinguish these neoplasms. Limited immunohistochemical stains are available to separate these two tumors.

METHODS

CD10 protein immunohistochemistry was performed on paraffin-embedded biopsies of 13 TE and 23 BCC diagnosed by routine microscopy. Cases were analyzed for pattern of CD10 expression by tumor cells and surrounding stroma.

RESULTS

Twelve of 13 (92%) TE showed positive stromal immunoreactivity. Of these, eight cases also demonstrated positivity of the papilla, and two also showed positivity of the basaloid cells. No TE demonstrated epithelial expression alone. On the other hand, expression of CD10 by basaloid cells was identified in 20 (87%) cases of BCC. Stromal positivity was also identified in three cases of BCC. Condensation of CD10-positive stromal cells around basaloid nests was statistically significant in differentiating TE from BCC (p < 0.0001). Conversely, CD10-positive basaloid cells were seen predominantly in BCC (p < 0.0001).

CONCLUSIONS

This study demonstrates a statistically significant difference in CD10 staining pattern between TE and BCC. Thus, CD10 may be a useful adjunct marker in distinguishing these tumors.

Comparative study of CD34, alpha-SMA and h-caldesmon expression in the stroma of gynaecomastia and male breast carcinoma

AIMS

To address the fibroblastic/myofibroblastic nature of stroma in gynaecomastia and in male breast carcinoma, the expression of CD34, alpha-smooth muscle actin (SMA) and h-caldesmon in the stromal cells was investigated by immunohistochemistry.

METHODS AND RESULTS

Representative archival paraffin blocks were collected from male patients with gynaecomastia (32 cases) and mammary carcinoma (24 cases) between 1984 and 2004 and CD34, alpha-SMA and h-caldesmon were assessed immunohistochemically using a streptavidin-biotin method. Thirty cases of gynaecomastia showed a CD34+, alpha-SMA- and h-caldesmon- immunophenotype with different CD34 staining intensity in the various histological subtypes. Positivity for alpha-SMA and negativity for CD34 and h-caldesmon was found in a case of florid gynaecomastia relating to reactive fibrosis due to previous surgical intervention. Acquisition of alpha-SMA expression by stromal fibroblasts but absence of CD34 staining was identified in 22 cases of male breast carcinoma.

CONCLUSIONS

The immunophenotype of periductal connective tissue stroma in gynaecomastia appears to parallel the phenotype of normal breast stroma. In male breast carcinoma the stromal cell immunophenotype is similar to that of its female counterpart showing myofibroblastic differentiation. However alpha-SMA+ and CD34- are not specific to malignancy because such findings are also encountered in reactive fibrosis.

Circulating fibrocytes: collagen-secreting cells of the peripheral blood

Since the original description of circulating fibrocytes in 1994, our knowledge of this unique cell population has grown steadily. While initially described in the context of wound repair, fibrocytes have since been found to participate in granuloma formation, antigen presentation, and various fibrosing disorders. Fibrocytes produce matrix proteins such as vimentin, collagens I and III, and they participate in the remodeling response by secreting matrix metalloproteinases. Fibrocytes also are a rich source of inflammatory cytokines, growth factors, and chemokines that provide important intercellular signals within the context of the local tissue environment. Moreover, fibrocytes express the immunological markers typical of an antigen-presenting cell, and they are fully functional for the presentation of antigen to naïve T cells. Fibrocytes can further differentiate, and they may represent a systemic source of the contractile myofibroblast that appears in many fibrotic lesions. Clinically, there is evidence that patients with hypertrophic scars such as keloids, and those affected by scleroderma and other fibrosing disorders have fibrocytes in their lesions. Recently, a new disease entity called nephrogenic fibrosing dermopathy (NFD) has been described, and the fibrocyte may play an important etiopathogenic role in disease development. Nephrogenic fibrosing dermopathy occurs in patients with renal insufficiency and leads to thickening and hardening of the skin, especially of the extremities. Ongoing research is focusing on the molecular signals that influence fibrocyte migration, proliferation, and function in the context of normal physiology and pathology.

Proliferative characterization of basal-cell carcinoma and trichoepithelioma in small biopsy specimens

We examined the proliferative characteristics of 20 basal-cell carcinomas (BCCs) and 16 trichoepitheliomas (TEps) in an effort to understand and explore possible differences in their tumorigenic cell-cycle properties. These tumors were first compared for their expression of the nuclear proliferative protein Ki-67 and the tumor suppressor protein p53. We also compared the p53 downstream effector, p21(waf-1/cip-1), an inhibitor of cyclin-dependent kinases. The other p53-dependent, cyclin-dependent kinase inhibitor, p27(kip-1), has shown to be increased in TEps, which is consistent with this benign neoplasm's better-differentiated state. In our findings, we confirmed through immunohistochemical staining for Ki-67 that BCCs qualitatively showed a greater proliferative fraction compared to TEps (50.0 vs. 13.0%, p < 0.00001) as well as over-expression of p53 (2+ vs. 1+, p < 0.0008). BCCs marked by p21 demonstrated scattered nuclear positivity compared to the virtual absence of staining in the TEps (p < 0.019). In studying their cell-cycle properties, our findings suggest that abnormalities in the p53 pathway allow BCCs to obtain a growth advantage. We show that Ki-67 and p53 staining both appear useful in resolving challenging differential diagnoses and thereby help in directing appropriate treatment strategies.

Immunohistochemical characterization of fibroblast subpopulations in normal peritoneal tissue and in peritoneal dialysis-induced fibrosis

Peritoneal fibrosis is one of the most common morphological changes observed in continuous ambulatory peritoneal dialysis (CAPD) patients. Both resident fibroblasts and new fibroblast-like cells derived from the mesothelium by epithelial-to-mesenchymal transition are the main cells involved fibrogenesis. In order to establish markers of peritoneal impairment and pathogenic clues to explain the fibrogenic process, we conducted an immunohistochemical study focused on peritoneal fibroblasts. Parietal peritoneal biopsies were collected from four patient groups: normal controls ( n = 15), non-CAPD uremic patients ( n = 17), uremic patients on CAPD ( n = 27) and non-renal patients with inguinal hernia ( n = 12). To study myofibroblastic conversion of mesothelial cells, alpha-smooth muscle actin (SMA), desmin, cytokeratins and E-cadherin were analyzed. The expression of CD34 by fibroblasts was also analyzed. Fibroblasts from controls and non-CAPD uremic patients showed expression of CD34, but no myofibroblastic or mesothelial markers. The opposite pattern was present during CAPD-related fibrosis. Expression of cytokeratins and E-cadherin by fibroblast-like cells and alpha-SMA by mesothelial and stromal cells supports that mesothelial-to-myofibroblast transition occurs during CAPD. Loss of CD34 expression correlated with the degree of peritoneal fibrosis. The immunophenotype of fibroblasts varies during the progression of fibrosis. Myofibroblasts seem to derive from both activation of resident fibroblasts and local conversion of mesothelial cells.

There is more than one kind of myofibroblast: analysis of CD34 expression in benign, in situ, and invasive breast lesions

AIMS

Smooth muscle actin (SMA) positive myofibroblasts have been implicated in tumour invasion; however, acquisition of SMA is not limited to peritumorous fibroblasts and other changes in fibroblasts may be more specifically related to the malignant environment. CD34 is a sialomucin expressed by normal breast fibroblasts but lost in invasive carcinomas. The aim of this study was to establish the relation between CD34 and SMA expression in breast fibroblasts and to analyse whether loss of CD34 is specific for invasive disease.

METHODS

Immunohistochemistry for CD34 and SMA was performed on 135 cases including 10 normal, 10 fibroadenomas, 40 infiltrating ductal carcinomas, 55 cases of ductal carcinoma in situ (DCIS), and 20 radial scar/complex sclerosing lesions. The relation between staining pattern and histopathological features was recorded as positive, negative, or reduced.

RESULTS

Fibroblasts around all normal duct-lobule units and those showing epithelial hyperplasia were CD34 positive and mainly SMA negative. In fibroadenomas, fibroblasts retained CD34 but acquired SMA expression. In contrast, fibroblasts around invasive carcinoma were CD34 positive and SMA negative. In DCIS, loss of CD34 was significantly more frequent in high grade tumours than in low or intermediate grade ones (p < 0.001). The acquisition of SMA was seen more frequently than the loss of CD34, particularly in non-high grade DCIS. In all radial scars, fibroblasts were SMA positive but CD34 negative, and a similar pattern was seen in stromal cells in areas of fibrosis following core biopsy.

CONCLUSIONS

These results show that SMA positive myofibroblasts exhibit variable expression of CD34, indicating that these markers are not coordinately controlled. Loss of CD34 is strongly related to the malignant phenotype, in both invasive and preinvasive disease, but is not entirely specific because radial scar fibroblasts and fibroblasts in reactive fibrosis exhibit a similar phenotype. The functional relevance of altered CD34 expression is unclear but the very focal changes implicate local signalling mechanisms probably of epithelial origin.

Expression of p27kip1 in basal cell carcinomas and trichoepitheliomas

Immunohistochemical analysis was used to evaluate p27kip1 expression in normal hair follicles and in a series of 39 basal cell carcinomas (BCC) (13 of superficial type, 7 infiltrating, 7 morphea-like, 12 nodular) and 20 trichoepitheliomas (TE) (9 of classic type, 9 immature, 2 desmoplastic). The labeling index (LI) was derived semiautomatically by means of a computer-assisted cellular image analyzer, and statistical analysis was carried out using the Student t test. A positive reaction for p27kip1 was detected in the hair germ papillae, in supramatrical cells, and in the inner pilar sheath, whereas matrical cells and the outer pilar sheath were negative. All BCC and TE cases showed a positive immunoreaction for p27kip1, but the staining pattern was different in the two groups of lesions, being patchy with focal peripheral accentuation in TE and more diffusely dispersed in BCC. The quantitative study showed lower p27kip1 expression in BCC (LI = 27.51 +/- 12.55) than in TE (LI = 45.27 +/- 20.27) (P < 0.0001). Statistically significant differences were also observed between TE subgroups and nodular or infiltrating BCC subtypes. The occurrence of a wide overlap of LI values hampers the practical application of a p27kip1 LI in the differential diagnosis between BCC and TE in difficult cases, however.

CD34-positive stromal cells and alpha-smooth muscle actin-positive stromal cells in the tumor capsule of skin sweat gland neoplasms

To elucidate the roles of CD34-positive stromal cells and alpha-smooth muscle actin-positive stromal cells at the tumor border of skin sweat gland neoplasms, we examined expression of stromal cell markers in the tumor capsule of 19 skin sweat gland neoplasms (16 mixed tumors of the skin and three nodular hidradenomas) using monoclonal antibodies to CD34, CD31, cytokeratin 14 (CK14), alpha-smooth muscle actin (ASMA) and high molecular weight caldesmon (HCD). We regarded CD34-positive, CD31-, CK14-, ASMA- and HCD-negative stromal cells to be CD34-positive stromal cells, and ASMA-positive, HCD-, CK14-, CD34- and CD31-negative stromal cells to be ASMA-positive stromal cells. CD34-positive stromal cells were detected in the tumor capsule of all 19 of the tumors examined. In nine of the 16 mixed tumors (56%) and all of the three nodular hidradenomas, ASMA-positive stromal cells were detected at the immediate inner side of the CD34-positive stromal cell layers. These results indicate that cellular components in the tumor capsules of mixed tumors of the skin and nodular hidradenomas are CD34-positive stromal cells and ASMA-positive stromal cells, and suggest that stromal cells of these two cell types are associated with tumor capsule formation of skin sweat gland neoplasms.

Trichoepithelioma with "monster" stromal cells

Trichoepithelioma is a benign tumor of trichogenic origin which appears predominantly in childhood or in young adults. Different forms have been described according to clinical and histological features. The authors report a unique variant of trichoepithelioma arising on the limb of a 27-year-old man. The tumor was characterized by the mixture of an atypical fibroxanthomatous proliferation and basaloid epithelial strands of trichoepithelioma. Such histological features have not been previously reported. It raises the question of an additional variant of hair follicle tumor with a mixed epithelial and mesenchymal proliferation.

Dendritic interstitial and myofibroblastic cells at the border of salivary gland tumors

OBJECTIVE

CD34-positive dendritic interstitial cells may be associated with the regulation of tumor growth. This association has been studied in various human neoplasms, especially skin tumors. In this study, we evaluated the distribution of dendritic interstitial cells and myofibroblastic cells at the tumor periphery of various benign and malignant salivary gland neoplasms.

METHODS

Forty-nine cases of salivary gland tumors were selected: 16 pleomorphic adenomas, 12 Warthin tumors, 8 polymorphous low-grade tumors, 5 adenoid cystic carcinomas, 6 acinic cell carcinomas, and 2 mucoepidermoid carcinomas. Immunohistochemical analysis was performed by using antibodies for CD34 (dendritic cells) and alpha-smooth muscle actin (myofibroblast) on formalin-fixed, paraffin-embedded archival tissue. Staining intensity was graded as marked (3+), moderate (2+), weak (1+), and absent (0).

RESULTS

Staining intensity for CD34 was 3+ in 24 (86%) of 28 benign tumors (pleomorphic adenomas and Warthin tumors) and 6 (29%) of 21 malignant tumors (polymorphous low-grade tumors, acinic cell carcinomas, adenoid cystic carcinomas, and mucoepidermoid carcinomas) and 2+ in 4 (19%) of 21 malignant tumors. None of the benign tumors displayed 2+ staining with CD34. Three (11%) of 28 benign and 11 (52%) of 21 of malignant tumors failed to stain with CD34. alpha-Smooth muscle actin staining was 3+ in 10 (36%) of 28 benign tumors and 6 (29%) of 21 malignant tumors, and 2+ in 11 (39%) of 28 benign and 2 (9%) of 21 malignant tumors. Five (18%) of 28 benign and 11 (52%) of 21 malignant tumors failed to stain with alpha-smooth muscle actin.

CONCLUSION

We conclude that the dendritic interstitial cells and myofibroblastic cells may be associated with the regulation of tumor growth in salivary gland tumors.

Basal cell carcinoma with tumor epithelial and stromal giant cells: a variant of pleomorphic basal cell carcinoma

A case of basal cell carcinoma with giant cells of the central epithelial and surrounding stromal components is presented. The lesion was an 8-mm dome-shaped papule on the ear of a 66-year-old man. The giant cells of the epithelial component shared the immunophenotype of the more typical cells of the basal cell carcinoma (keratin, smooth muscle actin, and bcl-2 positive), whereas the stromal giant cells were positive only for bcl-2. This case represents a peculiar variant of pleomorphic basal cell carcinoma, the significance of which is unknown.

An immunohistochemical study of basal cell carcinoma and trichoepithelioma

The histologic distinction between tricheopithelioma and basal cell carcinoma may be difficult in small biopsies. Immunohistochemical stains have been used to help make this distinction; however, published studies have generally been limited to a few antibodies. To this end we performed a comprehensive immunohistochemical analysis of 20 basal cell carcinomas and 10 tricheopitheliomas from our files, in search of a consistent pattern of reactivity to distinguish the neoplasms in biopsies. The antibodies used were: low molecular weight keratin (Cam 5.2), Cytokeratin 7, (CK7), Cytokeratin 20, (CK20), Carcino-embryonic antigen (CEA), CD30 (Ki-1), bcl-2, Ham 56, HPCA-I (CD34), and Ulex Europaeus type I. In our study, bcl-2 stained all but one basal cell carcinoma in a diffuse pattern, whereas all tricheopitheliomas showed staining of the outermost epithelial layer. No other stain proved to be an independent marker for either neoplasm and no consistent immunohistochemical profile for either neoplasm emerged. Thus, we conclude that bcl-2 may be of some value in distinguishing basal cell carcinoma from tricheopithelioma, limited by the quantitative nature of the difference in staining. Histologic criteria applied to H&E-stained sections remain the cornerstone of histologic diagnosis.

The use of immunostaining for bcl-2 and CD34 and the lectin peanut agglutinin in differentiating between basal cell carcinomas and trichoepitheliomas

Fifteen unequivocal basal cell carcinomas (BCC) and ten unequivocal trichoepitheliomas (TE) were studied using the lectin peanut agglutinin (PNA), and the monoclonal antibodies Q bend 10 and bcl-2 oncoprotein directed against the antigens CD34 and bcl-2, respectively, to see whether these markers could be used to differentiate between the two tumors. Ten percent of TE demonstrated a continuous band-like peritumorous staining with PNA and 80% demonstrated a discontinuous band-like peritumorous staining with PNA, with the comparable figures for BCC being 40% and 20%, respectively. In addition, 40% of BCC showed focal areas of pemphigus-like staining in contrast with only 10% of TE. Using the antibody directed against bcl-2, TE demonstrated weak staining mainly confined to the basal layer of tumor cells in 20% of cases and staining of the cells throughout the tumor in 30% of cases. Similarly, BCC also showed staining of the basal layer of tumor cells in 7% of specimens and staining of cells throughout the tumor mass in 40% of specimens studied. Finally, with the antibody Q bend 10 directed against CD34, staining of the immediate peritumoral spindle-shaped cells was observed in 20% of TE compared with 7% of BCC. Despite reports in the literature, we found that none of these three markers can be reliably used to differentiate between TE and BCC.

Diagnostic value of CD34 immunostaining in desmoplastic trichilemmoma

Desmoplastic trichilemmoma (DT) is a variant of trichilemmoma, characterized by a central prominent desmoplastic component which may simulate invasive carcinoma. We have studied the morphologic and immunohistochemical features of seven cases of DT. Immunohistochemistry was performed on paraffin sections using monoclonal antibodies to CD34 (QBEND/10), vimentin and GCDFP-15. CD34 was also tested in seven cases of basal cell carcinoma (BCC), three with outer root sheath differentiation and four with morphea-form features, and five squamous cell carcinomas. Histologically, features of conventional trichilemmoma were seen at the periphery of the seven lesions. In contrast, at the center, the epithelial cells tended to cluster in narrow irregular cords and nests entrapped in a dense collagenous stroma. One case of DT coexisted with a BCC. In all cases of DT, epithelial tumor cells showed CD34 immunostaining. All cases of BCC, including the one contiguous to a DT, were CD34 negative. CD34 immunodetection in the epithelial cells of the pseudoinvasive component of DT may be of great value in the differential diagnosis with other desmoplastic tumors of the skin, and particularly with BCC.

Immunohistologic differential diagnosis of basal cell carcinoma, squamous cell carcinoma, and trichoepithelioma in small cutaneous biopsy specimens

The distinction between squamoid basal cell carcinoma and basaloid squamous cell carcinoma (or between BCC and trichoepithelioma variants) is usually made readily on the basis of defined histological criteria. However, these differential diagnoses occasionally can pose difficult morphological problems. The stated distinctions are clinically important because the risk of progressive disease is significantly higher with squamous carcinoma of the skin than with basal cell carcinoma (BCC), and a trichoepithelioma misinterpreted as BCC burdens the patient with an inaccurate diagnosis that may result in inappropriate surgery. Recent reports have suggested that reactivity with the monoclonal antibody Ber-EP4 is capable of separating histologically similar basal cell and squamous carcinomas, and that the expression of bcl-2 or CD34 antigen is able to distinguish BCC from trichoepithelioma. However, corroborative studies of these contentions are few in number. In order to investigate the usefulness of the stated immunostains in the above-cited differential diagnoses, the authors analyzed 45 basal cell carcinomas and 22 squamous carcinomas, as well as 36 trichoepitheliomas. The monoclonal antibodies Ber-EP4, My10 (CD34), and anti-bcl-2 were applied to formalin-fixed paraffin sections in all cases, using a standard avidin-biotin-peroxidase complex method. Most BCCs demonstrated strong, diffuse cytoplasmic labeling with Ber-EP4 and anti-bcl-2. In contrast, the squamous carcinomas were uniformly negative for the former marker and only focally reactive for the latter in four examples. 'Peripheral' bcl-2 staining of trichoepitheliomas was noted in 24 of 33 of the immunoreactive tumors, but the remainder were marked diffusely and similarly to most BCCs. Among the latter, immature trichoepitheliomas were diffusely reactive for this marker in 6 of 8 cases. Labeling of epithelium for CD34 failed to discriminate between any of the tumor types under evaluation, whereas staining of peritumoral stroma was characteristic of the majority of trichoepitheliomas and more than one-third of metatypical basal cell carcinomas. These data support the suggestion that Ber-EP4 and bcl-2 are useful in the separation of BCC from squamous carcinomas. Nevertheless, they also serve to caution against reliance upon bcl-2 and CD34 immunostains in attempting to distinguish BCC from trichoepithelioma in histologically enigmatic cases. There is currently no certain method other than conventional microscopy that can be applied successfully to the latter problem.

Basal cell carcinoma with thickened basement membrane: a variant that resembles some benign adnexal neoplasms

Because cutaneous basal cell carcinoma (BCC) is such a common malignancy, its unusual histologic manifestations are important. We identified a variant of BCC in which thickened basement membranes surround aggregations of neoplastic epithelial cells. Thickened basement membranes of similar appearance have previously been observed in benign cutaneous adnexal neoplasms, in basaloid monomorphic adenomas of the salivary gland and in other benign conditions, such as folliculocentric basaloid proliferation. We identified nine BCCs that otherwise met standard criteria, but which also had thick basement membranes surrounding some of the aggregations, and examined them by routine and histochemical staining. The cases included BCC with nodular, micronodular, and infiltrating patterns. Two neoplasms were composed largely of clear cells, suggesting, together with the thickened membranes, outer root sheath differentiation. CD34, which labels keratinocytes of the outer root sheath, marked only the epithelial cells of one of these cases. The thickened membranes were stained by periodic-acid Schiff with and without diastase (PAS-D) and by antibodies to type IV collagen and laminin, with slightly different staining patterns. Intraepithelial droplets within aggregations stained with PAS-D and type IV collagen antibodies. Thickened basement membranes therefore can occur in most of the common growth patterns of BCC. The absence of CD34 staining of epithelial cells in most cases makes it problematic at this time to prove that the thickened membranes indicate trichilemmal differentiation. BCC with thick basement membranes can closely mimic benign neoplasms, such as cylindroma and trichilemmoma, from which they can be distinguished in routinely stained sections. The presence of a continuous thick basement membrane around aggregates of epithelial cells does not in and of itself distinguish between benign and malignant cutaneous epithelial neoplasms.

Dermatopathologic advances in clinical research. The expression of antibody to CD34 in mucocutaneous lesions. off

The human progenitor cell antigen, CD34, is selectively expressed in most hematopoietic colony-forming cells from normal human bone marrow, and in a significant proportion of acute leukemias. Within the dermis, CD34 is normally expressed by endothelial cells, dendritic cells, and the spindle-shaped cells around adnexal structures. Benign and malignant vascular lesions, adnexal tumors differentiating toward the external root sheath (trichilemmomas and pilar tumors), specific benign soft tissue tumors (spindle cell lipoma and solitary fibrous tumors), and many of the gastrointestinal stromal tumors uniformly express CD34 antigen. CD34 expression is also often present in benign tumors of neural origin; however, it is less consistently present in malignant peripheral nerve sheath tumors.