Abstract P1-09-18: A clinically validated DNA microarray for high-resolution HER2 testing defines a new genomic subtype in high-risk breast cancer with equivocal results by IHC and FISH

Background: In all stages of breast cancer, the HER2 status of a patient's tumor is critically important as both a prognostic indicator, and for predicting response to targeted anti-HER2 therapies. CAP/ASCO 2013 guidelines recommend that newly diagnosed, recurrent, and metastatic breast tumors be evaluated for HER2 positivity by protein-based immunohistochemistry (IHC) and/or chromosome-based fluorescence in situ hybridization (FISH). In the majority of cases, these testing modalities provide a clearly actionable “positive” or “negative” answer. However, in an estimated 10- to 20% of breast cancers, both tests are reported as “equivocal” leaving the clinician with a treatment decision dilemma and no definitive alternative testing method. Here we report validation of an IHC-targeted DNA microarray comparative genomic hybridization (array CGH) assay for HER2 equivocal breast cancer, and definition of a new genomic subtype of HER2 status in high-risk breast cancer with equivocal IHC and FISH results.

Methods: IHC-targeted HER2 receptor “hot spot” DNA samples extracted from 25 formalin fixed paraffin embedded (FFPE) breast tumor tissue samples previously characterized by IHC and FISH, were analyzed by array CGH. Eight tumors were known to be highly HER2 positive, seven tumors had IHC scores of 0 with negative FISH, and ten tumors had HER2 receptor staining by IHC (1-2+) and equivocal results by FISH (4-6 HER2 gene copies.) Tumor DNA (test) and human genomic DNA (reference) were fluorescently labeled, and competitively hybridized to a custom-designed genomic DNA microarray with high-density probe coverage of the HER2 amplicon on chromosome 17 (Agilent Technologies, Santa Clara CA). The array design includes over 4,600 chromosome 17 probes representing the p arm, q arm, telomeric and centromeric regions with 66 tiling probes over the HER2 (ERBB2) gene. Following hybridization, average HER2 gene copy number was calculated for each tumor sample by converting mean log2 signal intensity ratio value into genomic region copy number adjusted for % clonal fraction and experimentally established log2 ratio compression of the assay.

Results: 25/25 (100%) of samples yielded adequate DNA for analysis and all highly HER2 positive and HER2 negative results were confirmed by array CGH. In 10/10 IHC equivocal cases with HER2 gene copy number 4-6 by FISH, CGH results confirmed HER2-Low gene copy number.

Results for 25 Validation SamplesNumber of CasesIHC ScoreFISHCGH Copy NumberResult83+Positive> 6HER2-Positive101-2+Equivocal4-6HER2-Low70Negative< 6HER2-Negative

Conclusions: High-resolution HER2 testing by IHC-targeted DNA microarray analysis accurately classifies HER2 status in breast cancer and better defines the HER2-Low genomic subtype most often called “equivocal” by standard IHC and FISH testing. This subcategory is characterized at the protein level by IHC evidence of anti-HER2 therapy target receptor expression on the surface of the cells, and at the genomic level by HER2 gene copy number < 6. Results of the NSABP-B47 clinical trial and further studies with larger numbers of HER2-Low patients are needed to determine if these patients benefit from anti-HER2 therapy.

Citation Format: Gunn S, Yaziji H, Sims C, Govender S, Moore M, Cotter P, Jones S. A clinically validated DNA microarray for high-resolution HER2 testing defines a new genomic subtype in high-risk breast cancer with equivocal results by IHC and FISH [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-09-18.

Assay result variability during determination of mismatch repair deficiency status using immunohistochemistry: A transatlantic comparative study

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Background: Colorectal cancer patients with deficient mismatch repair (dMMR) have significantly fewer recurrences and may respond less well to chemotherapy. Immunohistochemical (IHC) determination of MMR status is therefore recommended to identify patients in whom adjuvant therapy is not indicated, but little is known regarding the variability of assay results. We aimed to define MMR IHC assay variability in formalin-fixed, paraffin-embedded (FFPE) material from the QUASAR-1 colorectal cancer trial contained within heterogeneity-prone tissue microarrays (TMAs)

Methods: TMA sections of FFPE material from the QUASAR-1 trial were distributed to 2 independent laboratories (Leeds, UK and Vitro Molecular Laboratories [VML], FL, USA) for MMR IHC assays. Serial TMA sections were stained with MLH1/MSH2 using techniques blinded to the other laboratory. Each stained section was double-scored independently and results compared to determine inter-assay variability.

Results: Matched MMR data were available for 1224 cases of MLH1 and 1223 cases of MSH2. Of these, loss of expression of MMR (dMMR) was reported in 160 cases (13.1%) by VML and 179 cases (14.6%) by Leeds. 140 (11.4%) were dMMR in both labs, 20 cases (1.6%) by VML alone and 39 (3.2%) by Leeds alone. Discordant dMMR status was observed in 56/166 (34%) dMMR cases identified with MLH1 and 10/34 (29%) cases identified with MSH2. Kappa coefficients for inter-assay agreement were 0.798 (95% CI = 0.748 - 0.848) for MMR status overall, 0.778 (95% CI = 0.722 - 0.835) for MLH1 and 0.823 (95% CI = 0.714 - 0.932) for MSH2. 85% (33/39) of discordant Leeds dMMR colon cancers were in the right colon where dMMR is more common, compared to 47% of VML discordant dMMR cases.

Conclusions: Independent determination of MMR status by IHC on TMAs is associated with excellent inter-assay agreement. The reasons for MMR case discordance are under further investigation. These results further support routine MMR testing by IHC.

No significant financial relationships to disclose.

P504S immunohistochemical detection in 405 prostatic specimens including 376 18-gauge needle biopsies

P504S is a recently described, prostate cancer-specific gene that encodes a protein involved in the beta-oxidation of branched chain fatty acids. A recent study has shown that immunohistochemical detection of P504S gene product is a sensitive and specific marker of prostatic carcinoma in formalin-fixed, paraffin-embedded tissues. We performed a detailed analysis of P504S protein expression in a large series of prostate and bladder specimens with special emphasis on staining in specific morphologic patterns of prostatic adenocarcinoma, posthormonal and radiation therapy cases, and invasive urothelial carcinoma. A total of 366 prostate needle core biopsies from 124 patients with prostate cancer, 10 biopsies from 2 patients without prostate cancer, 28 prostatectomy specimens (16 with specific morphologic patterns, 7 posthormonal therapy and 5 postradiation therapy specimens), 5 bladder specimens with invasive urothelial carcinoma, and a single transurethral resection specimen from a patient with hormonally treated prostate cancer and invasive urothelial carcinoma were stained with P504S monoclonal antibody at a 1:250 dilution using standard heat-induced epitope retrieval and avidin-biotin technique. Extent (0, no staining; 1+, 1-10% staining; 2+, 11-50% staining; 3+, > or =51% staining) and location (luminal, subluminal, and diffuse cytoplasmic) of immunoreactivity in carcinoma and benign tissues were recorded. A total of 153 of 186 biopsies (82%) with prostatic adenocarcinoma stained for P504S. Pseudohyperplastic, atrophic, ductal, and mucinous prostatic carcinomas stained similarly, as did cases treated with hormone or radiotherapy. In 81 of 377 (21%) foci of benign prostatic tissue there was staining that was almost always focal, faint, and noncircumferential. Seminal vesicles did not stain for P504S. Five of six (83%) specimens with invasive urothelial carcinoma had 2+ staining and one case had focal staining. We conclude that immunohistochemistry for P504S has potential utility in the diagnosis of prostate cancer, including those treated by hormones and radiation. Circumferential luminal to subluminal and diffuse cytoplasmic staining is the most specific staining pattern for prostatic carcinoma and is almost never associated with benign prostatic tissue. However, a negative P504S immunostain does not automatically rule out prostate cancer, as 18% of cases were negative. Additionally, occasional benign glands, high-grade prostatic intraepithelial neoplasia, atypical adenomatous hyperplasia, and urothelial carcinoma may express P504S. Therefore, we think that P504S is best used only in conjunction with strict light microscopic correlation and preferably with high molecular weight cytokeratin immunostaining.

Low-grade (fibromatosis-like) spindle cell carcinoma of the breast

Spindle cell carcinoma of the breast, a variant of metaplastic carcinoma, includes a wide spectrum of lesions with histomorphologic and nuclear features ranging from overtly malignant to mildly atypical. Spindle cell carcinomas with mildly atypical features may resemble fasciitis, fibromatosis, or myofibroblastic tumors and therefore are often misinterpreted as such. A recent study has suggested that spindle cell carcinomas with a dominant fibromatosis-like phenotype, unlike spindle cell carcinomas in general, have no propensity for distant metastasis and should be termed "tumors" rather than "carcinomas." To investigate the question of fibromatosis-like spindle cell breast carcinoma (FLSpCCs) metastatic potential, we studied cases of FLSpCC seen at the University of Texas M.D. Anderson Cancer Center between 1987 and 2000. Clinical, pathologic, and immunophenotypic features were reviewed, with emphasis on biologic behavior and predictors of clinical outcome. Our series included 24 women who ranged in age from 55 to 85 years (mean 66 years). Tumor size ranged from 1.0 to 5 cm (mean 2.8 cm). Most tumors were grossly well defined but had microscopic infiltrative borders. Tumors showed a dominant fibromatosis-like or myofibroblastic-like growth pattern with prominent collagenization. Inflammatory infiltrate was noted in the majority of tumors. Cytokeratin-positive cells were seen in all cases and usually appeared as cords or sheets of polygonal cells; isolated cytokeratin-positive cells were rare. In most tumors immunoreactivity for smooth muscle actin (SMA) was confined to the cytokeratin-negative cells. In five cases intense co-expression of cytokeratin and SMA was noted. None of the tumors showed immunoreactivity for smooth muscle heavy chain myosin, estrogen receptors, progesterone receptors, or HER-2/neu. Ki-67 expression was noted in fewer than 5% of tumor cells. Treatment consisted of local excision (seven cases) or modified radical mastectomy (13 cases). Treatment was unknown in four cases. In patients who underwent axillary nodal dissection, no lymph node metastases were found. Two of the six patients who underwent local excision developed local recurrence. Two patients who underwent modified radical mastectomy developed lung metastases within 2 years after the initial diagnosis. The metastatic tumors were histologically similar to the primary tumors. Our findings indicate that FLSpCCs have the potential for local recurrence and distant metastasis and should be treated accordingly. Because FLSpCCs may be underdiagnosed as benign, the use of immunohistochemical studies, especially for cytokeratins and SMA, is essential in the evaluation of any spindle cell proliferations of the breast.

Renal angiomyolipoma: further immunophenotypic characterization of an expanding morphologic spectrum

BACKGROUND

Renal angiomyolipoma is a benign tumor histologically characterized by proliferation of spindle cells, epithelioid cells, and adipocytic cells in concert with many thick-walled blood vessels. To add further diagnostic confusion, an epithelioid cell-predominant variant of renal angiomyolipoma has recently been described. HMB-45 immunoreactivity correlates with ultrastructural striated organelles that closely resemble premelanosomes, although no evidence of melanogenesis has been documented in this tumor.

OBJECTIVE

To further characterize the immunophenotypic and ultrastructural profile of renal angiomyolipoma based on phenotypic cell type (epithelioid, spindle, and adipocytic cell).

DESIGN

Formalin-fixed, paraffin-embedded tissues from 27 renal angiomyolipomas and 8 renal cell carcinomas were immunostained with monoclonal antibodies to the melanoma-associated antigens HMB-45, HMB-50, NKI/C3 (CD63), and tyrosinase; the smooth muscle-related antigens calponin and muscle-specific actin (HHF-35); S100; and cytokeratin (CK). All renal angiomyolipomas were also immunostained with a polyclonal antibody to renin. Ultrastructural examination was performed on 9 selected cases.

RESULTS

All renal angiomyolipomas stained positive for HMB-45, HMB-50, NKI/C3, muscle-specific actin (HHF-35), and calponin. Overall, HMB-45, HMB-50, and NKI/C3 preferentially stained the epithelioid cells. Tyrosinase staining was present in 50% of the renal angiomyolipomas with adequate tissue for staining (12 of 24 cases); positive staining and intensity paralleled HMB-45, HMB-50, and NKI/C3. Muscle-specific actin (HHF-35) and calponin preferentially stained the spindle cells. The adipocytic cells stained positive for both melanoma-associated antigens and smooth muscle antigens. Epithelioid cells, spindle cells, and adipocytic cells were CK, S100, and renin negative. Ultrastructural findings paralleled immunohistochemical staining patterns. Premelanosome-like organelles and electron dense granules were more readily detected in the epithelioid cells within the tumor, whereas ultrastructural characteristics of smooth muscle cells were more easily found in the spindle cells. All renal cell carcinomas stained positive for CK, NKI/C3 staining was variable, and all were negative for HMB-45, HMB-50, smooth muscle actin (HHF-35), and calponin.

CONCLUSION

In renal angiomyolipoma, the epithelioid and spindle cells have preferential staining patterns for melanoma-associated antigens versus smooth muscle antigens, respectively. Positivity in renal angiomyolipoma for HMB-50, NKI/C3, and tyrosinase, in addition to HMB-45, provides evidence for the presence of different melanoma-associated gene products. Immunophenotypic overlap of the 3 histologically distinct renal angiomyolipoma cell populations suggests a common cell line, supporting a unitarian concept for renal angiomyolipoma. Ultrastructural characteristics of the 3 renal angiomyolipoma cell phenotypes parallel the immunophenotype, giving further support to a common cell line. Our study lends further credence to the perivascular epithelioid cell concept as proposed by Bonetti and colleagues.

Renal angiomyolipoma: further immunophenotypic characterization of an expanding morphologic spectrum

BACKGROUND

Renal angiomyolipoma is a benign tumor histologically characterized by proliferation of spindle cells, epithelioid cells, and adipocytic cells in concert with many thick-walled blood vessels. To add further diagnostic confusion, an epithelioid cell-predominant variant of renal angiomyolipoma has recently been described. HMB-45 immunoreactivity correlates with ultrastructural striated organelles that closely resemble premelanosomes, although no evidence of melanogenesis has been documented in this tumor.

OBJECTIVE

To further characterize the immunophenotypic and ultrastructural profile of renal angiomyolipoma based on phenotypic cell type (epithelioid, spindle, and adipocytic cell).

DESIGN

Formalin-fixed, paraffin-embedded tissues from 27 renal angiomyolipomas and 8 renal cell carcinomas were immunostained with monoclonal antibodies to the melanoma-associated antigens HMB-45, HMB-50, NKI/C3 (CD63), and tyrosinase; the smooth muscle-related antigens calponin and muscle-specific actin (HHF-35); S100; and cytokeratin (CK). All renal angiomyolipomas were also immunostained with a polyclonal antibody to renin. Ultrastructural examination was performed on 9 selected cases.

RESULTS

All renal angiomyolipomas stained positive for HMB-45, HMB-50, NKI/C3, muscle-specific actin (HHF-35), and calponin. Overall, HMB-45, HMB-50, and NKI/C3 preferentially stained the epithelioid cells. Tyrosinase staining was present in 50% of the renal angiomyolipomas with adequate tissue for staining (12 of 24 cases); positive staining and intensity paralleled HMB-45, HMB-50, and NKI/C3. Muscle-specific actin (HHF-35) and calponin preferentially stained the spindle cells. The adipocytic cells stained positive for both melanoma-associated antigens and smooth muscle antigens. Epithelioid cells, spindle cells, and adipocytic cells were CK, S100, and renin negative. Ultrastructural findings paralleled immunohistochemical staining patterns. Premelanosome-like organelles and electron dense granules were more readily detected in the epithelioid cells within the tumor, whereas ultrastructural characteristics of smooth muscle cells were more easily found in the spindle cells. All renal cell carcinomas stained positive for CK, NKI/C3 staining was variable, and all were negative for HMB-45, HMB-50, smooth muscle actin (HHF-35), and calponin.

CONCLUSION

In renal angiomyolipoma, the epithelioid and spindle cells have preferential staining patterns for melanoma-associated antigens versus smooth muscle antigens, respectively. Positivity in renal angiomyolipoma for HMB-50, NKI/C3, and tyrosinase, in addition to HMB-45, provides evidence for the presence of different melanoma-associated gene products. Immunophenotypic overlap of the 3 histologically distinct renal angiomyolipoma cell populations suggests a common cell line, supporting a unitarian concept for renal angiomyolipoma. Ultrastructural characteristics of the 3 renal angiomyolipoma cell phenotypes parallel the immunophenotype, giving further support to a common cell line. Our study lends further credence to the perivascular epithelioid cell concept as proposed by Bonetti and colleagues.

Atypical bile duct adenoma, clear cell type: a previously undescribed tumor of the liver

A variable proportion of bile duct adenomas of the liver are still confused with metastatic well-differentiated adenocarcinoma by surgeons and pathologists. We present here three examples of previously undescribed primary hepatic bile duct tumors that were composed almost entirely of clear cells that closely mimicked metastatic renal cell carcinoma. They were interpreted as atypical bile duct adenomas and occurred in two males and one female whose ages ranged from 25 to 64 years. All three tumors were incidental findings and measured from 0.8 to 1.1 cm. The clear neoplastic cells showed mild nuclear atypia and no mitotic activity. They were arranged in tubules and nests that focally infiltrated the hepatic parenchyma. For comparison, a case of clear cell cholangiocarcinoma and 13 conventional bile duct adenomas were examined. The clear cell cholangiocarcinoma was larger (6.0 cm) and had the tubular pattern of conventional cholangiocarcinoma and an abundant desmoplastic stroma. The clear cells of this tumor exhibited greater nuclear atypia and increased mitotic activity. All three atypical bile duct adenomas expressed cytokeratin (CK) 7, p53 protein, epithelial membrane antigen (EMA), and carcinoembryonic antigen (CEA); they were negative for CK20, vimentin, Hep Par 1, chromogranin, and prostatic specific antigen (PSA) and exhibited less than 10% of Ki-67-positive nuclei. One atypical bile duct adenoma displayed luminal immunoreactivity for villin. With the exception of Ki-67 reactivity, the 13 conventional bile duct adenomas and the clear cell cholangiocarcinoma had essentially a similar immunohistochemical profile as that of the atypical clear cell bile duct adenomas. The absence of an extrahepatic primary tumor, the histologic features, the immunohistochemical profile, and the fact that all patients are symptom-free 2 months to 18 years after wedge liver biopsy support the interpretation of atypical clear cell bile duct adenoma. The differential diagnosis with clear cell hepatocellular carcinoma and metastatic clear cell carcinomas is discussed.

Renal angiomyolipoma: further immunophenotypic characterization of an expanding morphologic spectrum

BACKGROUND

Renal angiomyolipoma is a benign tumor histologically characterized by proliferation of spindle cells, epithelioid cells, and adipocytic cells in concert with many thick-walled blood vessels. To add further diagnostic confusion, an epithelioid cell-predominant variant of renal angiomyolipoma has recently been described. HMB-45 immunoreactivity correlates with ultrastructural striated organelles that closely resemble premelanosomes, although no evidence of melanogenesis has been documented in this tumor.

OBJECTIVE

To further characterize the immunophenotypic and ultrastructural profile of renal angiomyolipoma based on phenotypic cell type (epithelioid, spindle, and adipocytic cell).

DESIGN

Formalin-fixed, paraffin-embedded tissues from 27 renal angiomyolipomas and 8 renal cell carcinomas were immunostained with monoclonal antibodies to the melanoma-associated antigens HMB-45, HMB-50, NKI/C3 (CD63), and tyrosinase; the smooth muscle-related antigens calponin and muscle-specific actin (HHF-35); S100; and cytokeratin (CK). All renal angiomyolipomas were also immunostained with a polyclonal antibody to renin. Ultrastructural examination was performed on 9 selected cases.

RESULTS

All renal angiomyolipomas stained positive for HMB-45, HMB-50, NKI/C3, muscle-specific actin (HHF-35), and calponin. Overall, HMB-45, HMB-50, and NKI/C3 preferentially stained the epithelioid cells. Tyrosinase staining was present in 50% of the renal angiomyolipomas with adequate tissue for staining (12 of 24 cases); positive staining and intensity paralleled HMB-45, HMB-50, and NKI/C3. Muscle-specific actin (HHF-35) and calponin preferentially stained the spindle cells. The adipocytic cells stained positive for both melanoma-associated antigens and smooth muscle antigens. Epithelioid cells, spindle cells, and adipocytic cells were CK, S100, and renin negative. Ultrastructural findings paralleled immunohistochemical staining patterns. Premelanosome-like organelles and electron dense granules were more readily detected in the epithelioid cells within the tumor, whereas ultrastructural characteristics of smooth muscle cells were more easily found in the spindle cells. All renal cell carcinomas stained positive for CK, NKI/C3 staining was variable, and all were negative for HMB-45, HMB-50, smooth muscle actin (HHF-35), and calponin.

CONCLUSION

In renal angiomyolipoma, the epithelioid and spindle cells have preferential staining patterns for melanoma-associated antigens versus smooth muscle antigens, respectively. Positivity in renal angiomyolipoma for HMB-50, NKI/C3, and tyrosinase, in addition to HMB-45, provides evidence for the presence of different melanoma-associated gene products. Immunophenotypic overlap of the 3 histologically distinct renal angiomyolipoma cell populations suggests a common cell line, supporting a unitarian concept for renal angiomyolipoma. Ultrastructural characteristics of the 3 renal angiomyolipoma cell phenotypes parallel the immunophenotype, giving further support to a common cell line. Our study lends further credence to the perivascular epithelioid cell concept as proposed by Bonetti and colleagues.

Quantitative evaluation of HER-2/neu status in breast cancer by fluorescence in situ hybridization and by immunohistochemistry with image analysis

We correlated quantitative results obtained in 40 invasive breast cancer cases for HER-2 gene amplification by fluorescence in situ hybridization with protein expression by immunohistochemical studies with computer-assisted image analysis. Fluorescence in situ hybridization (FISH) results were quantified as the mean number of fluorescent signals per nucleus, and immunohistochemical slides were read by semiquantitatively assessing membranous immunostaining intensity in tumor cells vs nonneoplastic breast tissue or quantitatively evaluated by image analysis. We found high correlation between immunohistochemical results by semiquantitative scoring and by image analysis. FISH results correlated with immunohistochemical results moderately when the staining intensity of only tumor cells was assessed and significantly better when the difference in staining intensity between tumor cells and nonneoplastic breast tissue was assessed. The correlation with FISH results was further improved when immunohistochemical study was combined with heat-induced epitope retrieval (HIER). Although FISH and immunohistochemical studies assess different aspects of the HER-2/neu gene (amplification vs overexpression), we found good correlation between the diagnostic techniques. The correlation was best when immunohistochemical studies were combined with HIER and assessed as the difference between tumor cells and nonneoplastic breast tissue.

E-cadherin reactivity of 95 noninvasive ductal and lobular lesions of the breast. Implications for the interpretation of problematic lesions

Studies suggest that E-cadherin is useful to classify epithelial breast lesions as ductal or lobular, but extensive experience with this antibody is lacking. We studied reactivity of lesions with classic and indeterminate morphologic features. We reviewed 95 lesions and divided them into unanimous and nonunanimous diagnosis groups; the unanimous group served as benchmark lesions to which E-cadherin reactivity could be standardized and compared. All 37 ductal lesions in the unanimous group had strong, diffuse E-cadherin reactivity. Two of 22 classic lobular carcinoma in situ (LCIS) lesions had sparse E-cadherin-reactive lobular cells within a few terminal duct lobular units. Neither displayed transition from nonreactive to reactive cells. Of 36 lesions in the nonunanimous group, 19 had insufficient morphologic features for definitive classification. Only 6 of 19 were E-cadherin reactive, including several minimally proliferative lesions. The other 17 lesions in the nonunanimous group had LCIS and ductal carcinoma in situ (DCIS) features. All had no E-cadherin, or strong membrane reactivity of constituent cells in varying proportions, without a transition between reactive and nonreactive cells. Results suggest that the majority of morphologically nondiagnostic atypical lesions are lobular, including those associated with DCIS. E-cadherin seems to be absent in most lobular lesions.

Primary alveolar soft part sarcoma of the stomach: a case report and review

Alveolar soft part sarcoma (ASPS) is a rare tumor typically located in skeletal muscles and muscolofascial planes. Isolated cases of ASPS have been described as arising in the viscera. We report a mesenchymal tumor of the stomach in a 54-year-old Italian woman without evidence of primary neoplasm elsewhere ten years following the initial diagnosis. The histologic, histochemical, immunohistochemical, and electron microscopic findings were all consistent with the diagnosis of ASPS and allowed differentiating it from morphologically similar and more common tumors, such as metastatic renal cell carcinoma and paraganglioma. The patient is alive and well ten years following the initial presentation.

Immunohistochemical analysis of gynecologic tumors

Ancillary techniques such as immunohistochemistry (IHC) enable the surgical pathologist to extract additional information from fixed, deparaffinized tissue specimens and to provide data critical to optimal clinical management of the patient. In this review of applications of IHC to the analysis of gynecologic malignancies, the usefulness of immunohistochemical analysis of neoplasms of the cervix, endometrium, and ovary is summarized. In the uterine cervix, dysplasia is associated with qualitative and quantitative alterations in the expression of the Ki-67 antigen expression, as well as an ability to detect human papillomavirus. Endometrial endometrioid adenocarcinomas display a highly characteristic immunophenotype, with coexpression of cytokeratin and vimentin and demonstration of foci of high molecular weight cytokeratin expression; in addition, IHC analysis of estrogen and progesterone receptor and p53 expression can provide important prognostic information about this tumor. Stromal tumors of the endometrium may display a partial smooth muscle immunophenotype, but novel markers such as CD10 provide new tools for the identification of these tumors. The immunophenotypes of the normal ovarian surface epithelium (OSE) and corresponding tumors display significant overlap with, but important distinctions from, mesothelium, and important new markers such as the Wilms tumor gene product can prove useful in the identification of carcinomas of the OSE. Important prognostic markers for carcinomas of the OSE include the HER-2/neu gene product and p53, alterations of which can both be assessed by IHC techniques. Finally, the recent availability of markers of ovarian stroma, including Melan-A and inhibin-alpha, has provided a means for the positive identification of ovarian stromal tumors, which can manifest protean histological appearances.

Cytokeratin 8 immunostaining pattern and E-cadherin expression distinguish lobular from ductal breast carcinoma

Immunohistochemistry using antibodies to cytokeratin 8 can serve as a valuable diagnostic tool for the differentiation of lobular from ductal carcinomas of the breast. In contrast with ductal carcinomas, which exhibit a peripheral-predominant immunostaining pattern, adjacent tumor cells "molding" to each other, lobular carcinomas exhibit a ring-like perinuclear immunostaining pattern, creating a "bag of marbles" appearance with neighboring tumor cells. This immunostaining pattern is stable even in the tumors that otherwise do not exhibit characteristic histomorphologic features (i.e., solid or pleomorphic type of a lobular carcinoma) and tumors that mimic growth patterns characteristic of the respective other tumor type (i.e., targetoid or single-file growth pattern in a ductal carcinoma). Furthermore, we demonstrate that ductal carcinomas express E-cadherin in a similar peripheral-predominant immunostaining pattern (33/33 cases), while all 15 lobular carcinomas were negative for E-cadherin, suggesting a role for E-cadherin in the architectural organization of the cytoskeletal scaffolding within the tumor cells.

Detection of stromal invasion in breast cancer: the myoepithelial markers

Breast cancer can only be life threatening when it becomes invasive, at which point it carries potential for spreading and metastasis. Therefore, it is critical to distinguish invasive carcinomas (IC) from noninvasive lesions, the latter including ductal carcinoma in situ (DCIS) and benign breast lesions. While this distinction is usually made based on histologic evaluation alone, in a small but significant number of cases, accurate diagnosis may be impossible, particularly in the context of core needle biopsies. To this end, a number of immunohistochemical markers have been utilized to help establish the presence (or absence) of stromal invasion. The fact that the loss of the myoepithelial cell (MEC) layer is a hallmark of IC (but not DCIS) suggests the use of antibodies to MEC to distinguish IC from DCIS. However, these markers have a wide range of specificity and sensitivity, with the potential for problems in interpretation. The use of many of these markers is limited by high rates of 'false positive' or 'false negative' immunostaining. In this review, the biology of stromal invasion in breast carcinomas will be discussed, as well as the various myoepithelial markers, with emphasis on pitfalls related to their sensitivity and specificity in the detection of MECs in the breast. Finally, the authors will discuss diagnostically challenging breast lesions, which may require the use of MEC marker studies to reach a definitive diagnosis.

HER-2/neu protein expression in breast cancer evaluated by immunohistochemistry. A study of interlaboratory agreement

Immunohistochemistry (IHC) is used commonly for evaluating HER-2/neu protein expression in breast cancer. Given the potential clinical importance of HER-2/neu status in patient management, interlaboratory variability in HER-2/neu IHC results in a matter of legitimate concern. We compared the results from 2 laboratories for HER-2/neu determined by IHC on paraffin sections of the same 100 consecutive invasive breast cancers. Both laboratories used the same primary antibody; however, different methods for heat-induced epitope retrieval (microwave or steam) and immunostaining (automated equipment from different manufacturers) and different scoring systems (positive-negative and 0-4+) were used. Slides were read in a blinded fashion and the results from the 2 laboratories were compared. Of the 93 cases evaluable in both laboratories, 24% were scored as HER-2/neu-positive at 1 laboratory, and 23% were scored as positive at the other. Complete concordance in categorization of HER-2/neu status between the 2 laboratories was achieved in 90 of 93 cases. Excellent interlaboratory agreement for HER-2/neu IHC was attained using the same primary antibody to HER-2/neu, even without standardization of assay method or scoring criteria. However, standardization of these parameters remains an important objective to optimize interlaboratory agreement.

Comparison of fluorescence in situ hybridization and immunohistochemistry for the evaluation of HER-2/neu in breast cancer

PURPOSE

To compare fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) in the determination of HER-2/neu status of breast cancers.

MATERIALS AND METHODS

FISH and IHC for HER-2/neu were performed on formalin-fixed paraffin sections of 100 consecutive invasive breast cancers. FISH was performed at Beth Israel Deaconess Medical Center, Boston, MA, using the Oncor/Ventana INFORM kit (Ventana Medical Systems, Tucson, AZ; formerly sold by Oncor, Inc, Gaithersburg, MD) in a laboratory certified as proficient in this procedure. IHC was performed at PhenoPath Laboratories, Seattle, WA, using a polyclonal antibody to the HER-2/neu protein. FISH and IHC were analyzed in a blinded fashion, and the results were then compared. Procedure and interpretation times and reagent costs for FISH and IHC were also compared.

RESULTS

HER-2/neu was amplified by FISH in 26% of cases, and 23% were HER-2/neu-positive by IHC. FISH and IHC were both assessable in 90 cases. Concordance between FISH and IHC results was seen in 82 of these cases (91%, P <.001). The FISH procedure required more technologist time and more interpretation time per case for the pathologist than IHC. Reagent costs were substantially higher for FISH than for IHC.

CONCLUSION

There is a high level of correlation between FISH and IHC in the evaluation of HER-2/neu status of breast cancers using formalin-fixed paraffin-embedded specimens. Although the choice of which assay to use should be left for individual laboratories to make based on technical and economic considerations, our results may make it difficult to justify the routine use of FISH for determination of HER-2/neu status in breast cancer.

Specificity of HercepTest in determining HER-2/neu status of breast cancers using the United States Food and Drug Administration-approved scoring system

PURPOSE

To evaluate the specificity of the HercepTest for Immunoenzymatic Staining (Dako Corp, Carpinteria, CA) for determining HER-2/neu protein expression in breast cancer.

MATERIALS AND METHODS

Forty-eight invasive breast cancers previously found to be HER-2/neu-negative by two different immunohistochemical (IHC) assays and not amplified for the HER-2/neu gene by fluorescence in situ hybridization were studied using the HercepTest kit. HercepTest was performed according to the manufacturer's guidelines, and the results were scored on a 0 to 3+ scale using the United States Food and Drug Administration (FDA)-approved grading system. In this system, cases scored as 2+ or 3+ are considered HER-2/neu-positive.

RESULTS

Among these 48 cases, the IHC score using the FDA-approved scoring system was 0 in four cases (8.3%), 1+ in 16 (33.3%), 2+ in 21 (43.8%), and 3+ in seven (14.6%). Therefore, 58.4% of these cases were categorized as HER-2/neu-positive, and the specificity of the HercepTest kit for HER-2/neu expression was 41.6%. However, with the use of a modified scoring system that took into account the level of staining of nonneoplastic epithelium, the specificity increased to 93.2%.

CONCLUSION

Our results indicate that the HercepTest kit, when used in accordance with the manufacturer's guidelines and the FDA-approved scoring system, results in a large proportion of breast cancers being categorized as positive for HER-2/neu protein expression and that many of these seem to be false-positives. Consideration of the level of staining of nonneoplastic epithelium resulted in improved specificity. The current FDA-approved scoring system for HercepTest results should be reevaluated before its widespread use in clinical practice.

Use of high-intensity focused ultrasound to control bleeding

OBJECTIVE

High-intensity focused ultrasound (HIFU) has been shown to be effective in controlling hemorrhage from punctures in blood vessels. The objective of the current study was to investigate the capability of HIFU to stop bleeding after a more severe type of vascular injury, namely longitudinal incisions of arteries and veins.

METHODS

The superficial femoral arteries, common femoral arteries, carotid arteries, and jugular veins of four anesthetized pigs were exposed surgically. A longitudinal incision, 2 to 8 mm in length, was produced in the vessel. HIFU treatment was applied within 5 seconds of the onset of the bleeding. The HIFU probe consisted of a high-power, 3.5-MHz, piezoelectric transducer with an ellipsoidal focal spot that was 1 mm in cross section and 9 mm in axial dimension. The entire incision area was scanned with the HIFU beam at a rate of 15 to 25 times/second and a linear displacement of 5 to 10 mm. A total of 76 incisions and HIFU treatments were performed.

RESULTS

Control of bleeding (major hemosatsis) was achieved in all 76 treatments, with complete hemostasis achieved in 69 treatments (91%). The average treatment times of major and complete hemostasis were 17 and 25 seconds, respectively. After the treatment, 74% of the vessels in which complete hemostasis was achieved were patent with distal blood flow and 26% were occluded. The HIFU-treated vessels showed a consistent coagulation of the adventitia surrounding the vessels, with a remarkably localized injury to the vessel wall. Extensive fibrin deposition at the treatment site was observed.

CONCLUSION

HIFU may provide a useful method of achieving hemostasis for arteries and veins in a variety of clinical applications.

Destructive tophaceous calcium hydroxyapatite tumor of the infratemporal fossa. Case report and review of the literature

Tophaceous pseudogout is one of the rarest forms of crystal deposition disease, typically presenting as a destructive and invasive mass involving the temporomandibular joint or the infratemporal fossa region in the absence of any other articular manifestations. Previous cases have been assumed to be caused by calcium pyrophosphate dihydrate (CPPD) crystal deposition, based on finding weakly birefringent crystals in the involved tissues. The authors present the unique case of a 65-year-old woman with a destructive and invasive facial mass extending to the middle cranial fossa with microscopic and clinical features consistent with tophaceous pseudogout. High-resolution x-ray crystallographic powder diffraction and Fourier transformed infrared spectroscopy subsequently revealed that the crystals were composed of calcium hydroxyapatite without CPPD. The patient was later found to have primary hyperparathyroidism and mild hypercalcemia. This case demonstrates that tissue deposits of calcium hydroxyapatite can cause a destructive and invasive mass containing weakly birefringent crystals and raises the question of whether previous cases attributed to tophaceous pseudogout resulting from CPPD actually were composed of birefringent calcium hydroxyapatite.

Hemostasis of punctured blood vessels using high-intensity focused ultrasound

The hemorrhagic complications of vascular injury can be significant. We report on the use of high-intensity focused ultrasound (HIFU) to stop the hemorrhage of punctured blood vessels in pigs. Two HIFU transducers with frequencies of 3.5 and 2.0 MHz, each equipped with a water-filled conical housing, were used. Major blood vessels (femoral artery and vein, axillary artery, carotid artery and jugular vein), 2-10 mm in diameter, of anesthetized pigs were exposed surgically and punctured with 14- and 18-gauge needles to produce moderate to profuse bleeding. Complete hemostasis was achieved in less than 3 min of HIFU treatment in most blood vessels, and all vessels were patent after the treatment. Both HIFU frequencies were effective in producing hemostasis. Gross examination of the HIFU-treated vessels showed a consistent hardening of the soft tissue surrounding the blood vessels, providing a seal for the puncture hole. Microscopic examination of the vessels showed a remarkably localized HIFU treatment, resulting in coagulation of the adventitia, and an extensive fibrin network around the vessels and in the puncture hole. The vessel walls exhibited focal swelling, without evidence of irreversible injury. HIFU may provide a useful method for achieving hemostasis of punctured and traumatized blood vessels in a variety of clinical settings.

Gestational herpes simplex virus hepatitis

Hepatitis due to herpes simplex virus (HSV) is unusual in healthy individuals. To date, only 56 cases of HSV hepatitis in adult patients have been reported, including 21 pregnant patients. We describe a 25-year-old white woman in her 30th week of gestation who had progressive acute hepatitis. Histologic examination of the liver biopsy specimen showed diffuse microabscesses involving more than 50% of the hepatic parenchyma, with multiple hepatocytes containing Cowdry type A and ground-glass nuclear inclusions. The diagnosis of herpes hepatitis was confirmed by positive immunoreactivity to HSV antibodies in the tissue sections. Intravenous acyclovir therapy was immediately initiated, and the patient's condition improved dramatically. She then had a normal baby at term. Subsequently, the patient had a second pregnancy and an uncomplicated vaginal delivery without recurrence of the disease. Even though alterations of the humoral and cell-mediated immunity occur during pregnancy, herpes hepatitis is rare in pregnant women. Since the prompt administration of antiviral drugs is a lifesaving measure, we recommend including HSV hepatitis in the differential diagnosis of acute hepatitis in pregnancy.

Role of p53 immunohistochemistry in differentiating reactive gliosis from malignant astrocytic lesions

P53 immunohistochemistry has been used to distinguish between malignant tumors and morphologically similar benign processes. In the central nervous system, a major diagnostic dilemma is caused by overlapping features of benign reactive astrocytic lesions and low-grade astrocytomas, especially with small biopsies. P53 immunoreactivity in astrocytes could be useful in differentiating benign reactive lesions from malignant astrocytomas. An immunohistochemical study on 110 brain lesions from 108 patients using a monoclonal antibody (DO-7) against p53 protein was conducted. Using the modified Ringertz and World Health Organization system, the specimens included 22 astrocytomas, 12 anaplastic astrocytomas, 42 glioblastoma multiforme tumors, three nonglial tumors, and 56 reactive astrocytic lesions to 25 neoplasms, nine infectious processes, six cerebrovascular disorders,one metabolic disorder, two vascular malformations, eleven degenerative/demyelinating lesions, and two unknown primary lesions. Immunoreactive astrocytic tumors included 12 (54%) astrocytomas, nine (75%) anaplastic astrocytomas, and 38 glioblastoma multiforme tumors (90%). Among the reactive astrocytic lesions, only five (9%) cases of progressive multifocal leukoencephalopathy were immunoreactive. These data demonstrate that p53 immunoreactivity in astrogliosis is unusual but is to be expected in astrocytomas and can help to differentiate reactive from neoplastic astrocytic lesions.

Primary small cell undifferentiated carcinoma of the rectum associated with ulcerative colitis

Primary small cell undifferentiated carcinomas (SCUCs) are unusual tumors of the colon and rectum. Histologically, these lesions represent a spectrum of neuroendocrine differentiation, with oat cell carcinoma being the most primitive subtype and carcinoid tumors being the most differentiated. This observation is supported by immunohistochemical and ultrastructural findings. We report a case of SCUC of the rectum in a patient with ulcerative colitis. To date, there have been only two reported cases of primary SCUC associated with ulcerative colitis. Recent theories of tumorigenesis attribute most colorectal cancers to a single, pluripotential mucosal stem cell, regardless of the tumor's histologic type.

Localization of tartrate-resistant acid phosphatase in human placenta

Tartrate-resistant acid phosphatase is an inducible marker of cell differentiation and activation expressed by specialized cells of macrophage lineage and some activated lymphocytes. Clinically, this phosphatase is a diagnostic marker for hairy cell leukaemia and osteoclast activity. The cDNA for this enzyme has been cloned from a placental expression library, yet the cell(s) expressing the enzyme protein has not been determined with certainty. Our laboratories have developed a monoclonal antibody, 9C5, suitable for immunohistochemical localization of tartrate-resistant acid phosphatase in paraffin sections. The purpose of this study was to use antibody 9C5 to identify cells expressing tartrate-resistant acid phosphatase in sections of paraffin-embedded, normal, full-term placenta and to determine if those cells expressed other macrophage markers including CD68 (PG-M1 antibody), LN5, lysozyme, alpha 1-antitrypsin and alpha 1-antichymotrypsin. Histochemical localization of activity in frozen sections was compared with immunohistochemical localization in paraffin sections of the same tissue specimens. The activity and antigenicity of this enzyme were detected in decidual cells, syncytiotrophoblast, and some macrophages distributed throughout maternal and embryonic tissues, but not in neutrophils. Unlike other tissues previously examined, placenta contains significant numbers of the phosphate-positive cells that are not of macrophage origin.

Immunohistochemical detection of tartrate-resistant acid phosphatase in non-hematopoietic human tissues

Immunohistochemical studies were done on formalin-fixed, paraffin-embedded tissues to evaluate the specificity of a newly developed monoclonal antibody (9C5) against tartrate-resistant acid phosphatase. Sections from 195 specimens were examined, which included 33 types of tissues/organs. These tissues included normal, inflammatory, and neoplastic processes. Neoplastic tissues from 14 patients with hairy cell leukemia served as positive controls. Epitope enhancement was accomplished either by microwave irradiation in citrate buffer or by boiling in water followed by trypsin digestion. Tissues were reacted with monoclonal antibody 9C5 and stained with either the avidin-biotin peroxidase method or the alkaline phosphatase anti-alkaline phosphatase method. The hairy cells of all cases of hairy cell leukemia reacted positively with 9C5. Other positively stained cells included osteoclasts, activated macrophages and giant cells. Immunohistochemical studies with 9C5, when interpreted within the context of the specificity of this antibody, are useful for the diagnosis and assessment of treatment results for hairy cell leukemia. Monoclonal antibody 9C5 also may be useful as a marker for osteoclasts and the activated macrophages and for the diagnosis of disorders involved by these cells.