Ductal carcinoma in situ: morphology-based knowledge and molecular advances.

Ductal carcinoma in situ (DCIS) is an established precursor of invasive breast carcinoma. Immunoperoxidase stains for selected markers can assist pathologists in the diagnosis of challenging ductal epithelial proliferations, but they cannot replace morphologic evaluation as the primary and critical assessment of this disease. Molecular studies provide further insight into how DCIS progresses to invasive carcinoma and also confirm the heterogeneity of this lesion. Morphology-based knowledge, immunohistochemistry, and molecular advances in DCIS are the subjects of this review.

Immunohistochemical staining with EGFR mutation-specific antibodies: high specificity as a diagnostic marker for lung adenocarcinoma.

We previously demonstrated a high specificity of immunohistochemistry using epidermal growth factor receptor (EGFR) mutation-specific antibodies in lung adenocarcinoma and correlation with EGFR mutation analysis. In this study, we assessed EGFR mutation status by immunohistochemistry in a variety of extrapulmonary malignancies, especially those that frequently show EGFR overexpression. Tissue microarrays containing triplicate cores of breast carcinomas (n=300), colorectal carcinomas (n=65), pancreatic adenocarcinoma (n=145), and uterine carcinosarcoma or malignant mixed müllerian tumors (n=25) were included in the study. Tissue microarray of lung adenocarcinoma with known EGFR mutation status was used as reference. Immunohistochemistry was performed using antibodies specific for the E746-A750del and L858R mutations. In pulmonary adenocarcinoma, a staining intensity of 2+ or 3+ correlates with mutation status and is therefore considered as positive. Out of 300 breast carcinomas, 293 (98%) scored 0, 5 (2%) had 1+ staining, 2 (1%) were 2+ for the L858R antibody. All breast carcinomas scored 0 with the E746-A750 antibody. All the colorectal, pancreatic carcinomas and malignant mixed müllerian tumors were negative (0) for both antibodies. Molecular analysis of the breast carcinomas that scored 2+ for L858R showed no mutation. Our results show that EGFR mutation-specific antibodies could be an additional tool distinguishing primary versus metastatic carcinomas in the lung. False-positivity can be seen in breast carcinoma but is extremely rare (1%).

Microglandular adenosis: a non-obligate precursor of triple-negative breast cancer?

Microglandular adenosis is a rare glandular lesion of the breast, which can mimic well-differentiated invasive carcinoma, and is characterized by a haphazard proliferation of uniform small round glands with open lumina and lacking a myoepithelial cell layer. This lesion has a rather unique immunohistochemical profile characterized by expression of cytokeratins and S-100, and lack of estrogen receptor (ER) and progesterone receptor (PR). The role of microglandular adenosis as a potential precursor of invasive breast cancer has long been a matter of controversy; however, recent molecular analyses have demonstrated that these lesions are heterogeneous at the genetic level, and that at least a subset of microglandular adenosis are clonal and display gene copy number alterations. Importantly, the pattern of genetic aberrations found in microglandular adenosis differs from that of other non-obligate precursors of ER-positive breast cancer. Carcinomas arising in microglandular adenosis are mostly of triple-negative phenotype (i.e. lack of ER, PR and HER2) and express S100, similar to microglandular adenosis. Genetic alterations found in microglandular adenosis have been shown to be similar to those found in synchronous invasive carcinomas. Here we review the clinical, morphological, and molecular features of microglandular adenosis, with an emphasis on its role as a non-obligate precursor of triple-negative breast cancer, and discuss areas for future research endeavors to clarify the clinical and biological significance of these fascinating lesions.

Id4 protein is highly expressed in triple-negative breast carcinomas: possible implications for BRCA1 downregulation.

BRCA1 germline mutation carriers usually develop ER, PR and HER2 negative breast carcinoma. Somatic BRCA1 mutations are rare in sporadic breast cancers, but other mechanisms could impair BRCA1 functions in these tumors, particularly in triple-negative breast carcinomas (TNBCs). Id4, a helix-loop-helix DNA binding factor, blocks BRCA1 gene transcription in vitro and could downregulate BRCA1 in vivo. We compared Id4 immunoreactivity in 101 TNBCs versus 113 non-TNBCs, and correlated the results with tumor morphology and immunoreactivity for CK5/6, CK14, EGFR, and androgen receptor (AR). Id4 was present in 76 out of 101 (75 %) TNBCs: 40 (40 %) TNBCs displayed Id4 positivity in >50 % of neoplastic cells, 23 (23 %) in 5-50 %, and 13 (13 %) in <5 %. In contrast, only 6 (5 %) of 113 non-TNBCs showed focal Id4 positivity, limited to fewer than 5 % of the tumor (p < 0.0001). Id4 expression significantly associated with high histologic grade (p = 0.0002) and mitotic rate (p = 0.006). Id4 decorated all 12 TNBCs with large central acellular zone of necrosis in our series, with positive staining in 10-90 % of the cells. Id4 signal strongly correlated with cytokeratin CK14 reactivity (p < 0.0001), but not with CK5/6 and EGFR. All apocrine carcinomas in our series were positive for AR and most for EGFR, but they were negative for CK5/6, CK14, and Id4, with only two exceptions. Our results document substantial expression of Id4 in most TNBCs, which could result in functional downregulation of BRCA1 pathways in these tumors.

Favorable prognosis in patients with T1a/T1bN0 triple-negative breast cancers treated with multimodality therapy.

BACKGROUND: The authors evaluated the clinical characteristics, natural history, and outcomes of patients who had ≤1 cm, lymph node-negative, triple-negative breast cancer (TNBC). METHODS: After excluding patients who had received neoadjuvant therapy, 1022 patients with TNBC who underwent definitive breast surgery during 1999 to 2006 were identified from an institutional database. In total, 194 who had lymph node-negative tumors that measured ≤1 cm comprised the study population. Clinical data were abstracted, and survival outcomes were analyzed. RESULTS: The median follow-up was 73 months (range, 5-143 months). The median age at diagnosis was 55.5 years (range, 27-84 years). Tumor (T) classification was microscopic (T1mic) in 16 patients (8.2%), T1a in 49 patients (25.3%), and T1b in 129 patients (66.5%). Most tumors were poorly differentiated (n = 142; 73%), lacked lymphovascular invasion (n = 170; 87.6%), and were detected by screening (n = 134; 69%). In total, 129 patients (66.5%) underwent breast-conserving surgery, and 65 patients (33.5%) underwent mastectomy. One hundred thirteen patients (58%) received adjuvant chemotherapy, and 123 patients (63%) received whole-breast radiation. The patients who received chemotherapy had more adverse clinical and disease features (younger age, T1b tumor, poor tumor grade; all P < .05). Results from testing for the breast cancer (BRCA) susceptibility gene were available for 49 women: 19 women had BRCA1 mutations, 7 women had BRCA2 mutations, and 23 women had no mutations. For the entire group, the 5-year local recurrence-free survival rate was 95%, and the 5-year distant metastasis-free survival rate was 95%. There was no difference between patients with T1mic/T1a tumors and patients with T1b tumors in the distant recurrence rate (94.5% vs 95.5%, respectively; P = .81) or in the receipt of chemotherapy (95.9% vs 94.5%, respectively; P = .63). CONCLUSIONS: Excellent 5-year locoregional and distant control rates were achievable in patients with TNBC who had tumors ≤1.0 cm, 58% of whom received chemotherapy. These results identified a group of patients with TNBC who had favorable outcomes after early detection and multimodality treatment.

Postchemotherapy histiocyte-rich pseudotumor involving the spleen.

We report 2 cases of splenic postchemotherapy histiocyte-rich pseudotumor. Each patient had a history of diffuse large B-cell lymphoma, treated with multiagent chemotherapy. Computed tomography scans performed on both patients showed splenic masses. A positron emission tomography scan performed on 1 patient showed increased metabolic activity. The preoperative diagnosis in both patients was recurrent lymphoma, prompting splenectomy. The splenectomy specimens showed multiple, tan-white, firm nodules, up to 3.5 cm in diameter, that were histologically composed of central necrotic B cells (CD20+/CD3-), consistent with necrotic lymphoma, surrounded by numerous lipid-laden (xanthomatous) histiocytes. Clinical staging studies at the time of splenectomy showed no other sites of disease. We conclude that these histologic and immunophenotypic findings represent chemotherapy-induced tumor necrosis with a florid histiocytic reaction mimicking residual viable lymphoma. Others have used descriptive terminology or the term xanthomatous pseudotumor for these lesions that have been only rarely reported in the spleen previously.

PNL2 melanocytic marker in immunohistochemical evaluation of primary mucosal melanoma of the head and neck.

BACKGROUND: Histologic diagnosis of mucosal melanoma of the head and neck is difficult, requiring immunohistochemical stains which are less reliable than in cutaneous lesions. PNL-2 is a novel marker that has not been examined in mucosal melanoma. METHODS: Nine formalin-fixed tissue sections of mucosal melanoma were stained with PNL-2, human melanoma black (HMB)-45, Melan-A, S-100, and microphthalmia transcription factor (MITF). RESULTS: Disease in all 9 patients arose from the sinonasal mucosa. Rates of diffuse positive staining with the 4 stains were PNL-2 (77.8%), HMB-45 (77.8%), Melan-A (50%), S-100 (87.5%), and MITF (40%). In 3 patients, PNL2 staining was superior to Melan-A or MITF. CONCLUSION: We report the first characterization of PNL-2 staining in head and neck mucosal melanoma. PNL-2 demonstrates high sensitivity for mucosal melanoma, likely superior to Melan-A and MITF, and comparable to HMB-45, with specificity superior to S-100. We advocate inclusion of PNL2 as an important adjunctive marker in the evaluation of these lesions.

Alterations in the expression of PDCD4 in ductal carcinoma of the breast.

Programmed cell death 4 gene (PDCD4), an in vivo repressor of transformation, was originally isolated from a human glioma library by screening it with an antibody against a nuclear antigen in proliferating cells. PDCD4 functions as a transformation repressor by inhibiting the activity of the RNA helicase, eIF4A. We previously showed that retinoids, anti-estrogens and HER2/neu antagonist induce PDCD4 expression in human breast cancer cell lines. Very little is known about the expression of PDCD4 in human breast cancer tissues or the significance of the PDCD4 expression in breast cancer. To gain insight into the pattern of the PDCD4 expression in breast tissues, we performed an immunohistochemical analysis of the PDCD4 expression in 80 archived, normal and ductal breast carcinoma tissues (invasive and carcinoma in situ) (DCIS) and correlated PDCD4 expression with expression of known prognostic markers in breast cancer (ER, PR and HER2/neu). To assess the role of methylation on PDCD4 expression in breast cancer cells, breast cancer cell lines were treated with the demethylating agent 5-deoxy-azacytidine and analyzed for PDCD4 expression. We observed primarily nuclear localization of PDCD4 in ductal carcinoma in situ compared to normal breast tissues where the PDCD4 expression was predominantly cytoplasmic. This was seen more frequently in DCIS cases that were ER positive and HER2/neu negative samples. PDCD4 expression was markedly decreased in the invasive ductal carcinoma. We did not observe any significant relationship between PDCD4 expression and the expression of RAR or PR. In T-47D, MDA-MB-435 and MDA-MB-231 cells, treatment with 5-deoxy-azacytidine did not result in an increased expression of PDCD4. The present study demonstrated altered cellular localization of PDCD4 when comparing normal breast to neoplastic breast tissues. In addition, there was a decreased expression of PDCD4 in breast cancer when compared with normal breast tissue. A loss of the PDCD4 expression in breast cancer cell lines does not appear to result from hypermethylation of the PDCD4 promoter.

Epidermal growth factor receptor in osteosarcoma: expression and mutational analysis.

Activation of intracellular mitogenic signal transduction pathways driven by the ErbB family of receptor tyrosine kinases has been implicated in the development and/or progression of a variety of cancers. Studies on ErbB receptors in osteosarcoma have focused on HER-2 and have produced conflicting results with few studies evaluating the expression of the epidermal growth factor receptor (EGFR). In this study, we determined the level of expression of EGFR and the mutational status of the EGFR receptor in a subset of osteosarcoma tumor samples as well as in a series of established bone tumor-derived cell lines. EGFR protein expression was detected in the form of strong membranous staining by immunohistochemistry in 21 (57%) of 37 cases analyzed. Six of 12 (50%) osteosarcoma cell lines revealed moderate to high expression levels of EGFR. Two somatic alterations (E829E and R831C) were identified in the cytoplasmic domain of the EGFR gene in 1 of 10 tumor samples. The significance of these findings for the pathobiology of osteosarcomas will be investigated further.