Authentication of a survival nomogram for non-invasive micropapillary breast cancer

Purpose

We aimed at establishing a nomogram to accurately predict the overall survival (OS) of non-metastatic invasive micropapillary breast carcinoma (IMPC).

Methods

In the training cohort, data from 429 patients with non-metastatic IMPC were obtained through the Surveillance, Epidemiology, and End Results (SEER) database. Other 102 patients were enrolled at the Xijing Hospital as validation cohort. Independent risk factors affecting OS were ascertained using univariate and multivariate Cox regression. A nomogram was established to predict OS at 3, 5 and 8 years. The concordance index (C-index), the area under a receiver operating characteristic (ROC) curve and calibration curves were utilized to assess calibration, discrimination and predictive accuracy. Finally, the nomogram was utilized to stratify the risk. The OS between groups was compared through Kaplan-Meier survival curves.

Results

The multivariate analyses revealed that race (p = 0.047), surgery (p = 0.003), positive lymph nodes (p = 0.027), T stage (p = 0.045) and estrogen receptors (p = 0.019) were independent prognostic risk factors. The C-index was 0.766 (95% CI, 0.682-0.850) in the training cohort and 0.694 (95% CI, 0.527-0.861) in the validation cohort. Furthermore, the predicted OS was consistent with actual observation. The AUCs for OS at 3, 5 and 8 years were 0.786 (95% CI: 0.656-0.916), 0.791 (95% CI: 0.669-0.912), and 0.774 (95% CI: 0.688-0.860) in the training cohort, respectively. The area under the curves (AUCs) for OS at 3, 5 and 8 years were 0.653 (95% CI: 0.498-0.808), 0.683 (95% CI: 0.546-0.820), and 0.716 (95% CI: 0.595-0.836) in the validation cohort, respectively. The Kaplan-Meier survival curves revealed a significant different OS between groups in both cohorts (p<0.001).

Conclusion

Our novel prognostic nomogram for non-metastatic IMPC patients achieved a good level of accuracy in both cohorts and could be used to optimize the treatment based on the individual risk factors.

Micropapillary Breast Carcinoma: From Molecular Pathogenesis to Prognosis

Invasive micropapillary carcinoma (IMPC) of the breast is an infrequent type of breast cancer often discussed for its potency for lymphovascular invasion and difficulty in accurate imaging estimation. Micropapillary carcinomas are noted to be present as larger tumors, of higher histological grade and a notably higher percentage of disease-positive lymph nodes. Hormonal and HER-2 positivity in IMPC is also commoner when compared to other NST carcinomas. IMPC occurs either as a pure form or more often as a component of mixed Non-Specific Type (NST) carcinoma. The latest data suggest that despite having comparable survival rates to other histological subtypes of breast carcinoma, effective surgical treatment often requires extended surgical margins and vigilant preoperative axillary staging due to an increased incidence of lymph node invasion, and locoregional recurrence. Moreover, the presence of micropapillary in situ components within tumors also seems to alter tumor aggression and influence the nodal disease stage. In this review, we present an overview of the current literature of micropapillary carcinoma of the breast from biology to prognosis, focusing on biological differences and treatment.

Special Histologic Type and Rare Breast Tumors - Diagnostic Review and Clinico-Pathological Implications

Breast cancer is the most common malignant tumor in females. While most carcinomas are categorized as invasive carcinoma, no special type (NST), a diverse group of tumors with distinct pathologic and clinical features is also recognized, ranging in incidence from relatively more common to rare. So-called "special histologic type" tumors display more than 90% of a specific, distinctive histologic pattern, while a spectrum of tumors more often encountered in the salivary gland may also arise in the breast. Metaplastic carcinomas can present diagnostic challenges. Some uncommon tumors harbor pathognomonic genetic alterations. This article provides an overview of the key diagnostic points and differential diagnoses for this group of disparate lesions, as well as the salient clinical characteristics of each entity.

HER2 Immunohistochemistry in Invasive Micropapillary Breast Carcinoma: Complete Assessment of an Incomplete Pattern

CONTEXT.—

Invasive micropapillary carcinoma (IMPC) is a rare variant of breast carcinoma, composed of avascular morula-like tumor clusters surrounded by stromal spaces, which can affect the HER2 immunohistochemical (IHC) staining pattern. The 2013 American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) HER2 testing guideline suggests moderate to intense but incomplete (basolateral) staining be considered equivocal.

OBJECTIVES.—

To perform a detailed assessment of HER2 IHC staining patterns in IMPC.

DESIGN.—

Hematoxylin-eosin and HER2 IHC slides were retrospectively reviewed to assess the morphology and HER2 IHC characteristics of IMPC. The 2018 ASCO/CAP guideline was applied.

RESULTS.—

The cohort consisted of 187 IMPCs from 181 patients with median age of 58 years. Homogeneous (≥90%) micropapillary component was found in 40% (75 of 187) of cases. Receptor profile was as follows: 75% (140 of 187) ER+ HER2-, 19% (37 of 187) ER+ HER2+, 4% (7 of 187) ER- HER2+, and 2% (3 of 187) ER- HER2-. Of 26 cases with HER2 IHC 3+, 65% (17 of 26) showed a basolateral staining pattern with strong intensity. HER2 fluorescence in situ hybridization (FISH) showed amplification in 26% (17 of 66) of HER2 IHC equivocal cases: 76% (13 of 17) showed basolateral staining pattern and 24% (4 of 17) complete staining, with weak to moderate (2), moderate (14), or moderate to strong (1) intensity.

CONCLUSIONS.—

The most frequent staining pattern was basolateral, seen in 49% of cases, including 65% HER2 IHC positive and 76% HER2 IHC equivocal/FISH amplified. If a basolateral pattern and weak to moderate staining is observed in IMPC, alternative testing should be performed to confirm the HER2 status.

Prognosis of lymphotropic invasive micropapillary breast carcinoma analyzed by using data from the National Cancer Database

Background

Invasive micropapillary carcinoma (IMPC) is an uncommon subtype of breast cancer. Previous studies of this subtype demonstrated a higher propensity for lymph node metastases as compared with invasive ductal carcinoma (IDC). The purpose of the present study was to determine the clinical characteristics, outcomes, and propensity for lymph node metastasis of patients with IMPC of the breast recorded in the National Cancer Database (NCDB).

Methods

Records of patients with IMPC diagnosed between 2004 and 2014 were retrieved from the NCDB. Log-rank test was performed to evaluate associations of clinical characteristics with overall survival (OS). Cox proportional hazards model was used to determine variables associated with OS.

Results

Overall, 2660 patients with IMPC met the selection criteria; the 5-year OS rate was 87.5% and 24.9% of patients had nodal involvement at presentation. Patients with ≥ 4 positive lymph nodes had shorter OS than node-negative patients, whereas patients with 1–3 positive nodes had similar OS to node-negative patients. Age < 65 years, receipt of radiotherapy, and estrogen receptor positivity were also associated with prolonged OS. The benefit of radiotherapy was limited to IMPC patients undergoing lumpectomy; there was no benefit for the patients undergoing mastectomy (regardless of nodal positivity/negativity).

Conclusions

Favorable prognostic factors of IMPC patients included age < 65 years, < 4 positive lymph nodes, receipt of radiotherapy, and estrogen receptor positivity. The results presented herein suggest a survival benefit associated with radiotherapy in IMPC treatment, though this may be limited to the patients treated with lumpectomy.

The impact of molecular status on survival outcomes for invasive micropapillary carcinoma of the breast

Invasive micropapillary carcinoma (IMPC) is an uncommon variant of breast cancer. Previous studies demonstrated this subtype is often hormone receptor (HR)-positive, resulting in survival outcomes similar to invasive ductal carcinoma. However, many of these studies were conducted prior to HER2 testing availability. We aim to determine the impact of molecular marker status (including HER2 status) on IMPC survival outcomes. The National Cancer Data Base (NCDB) was used to retrieve patients with biopsy-proven IMPC from 2007 to 2012. Only patients with known HR and HER2 status were included. Cox multivariate regression was used to determine prognostic factors. In total, 865 patients were included; median follow-up was 2.5 years. Overall, 651 patients (75.3%) had HR + HER2- disease, 128 (14.8%) had HR + HER2+ disease, 41 (4.7%) had HR-HER2 + disease, and 45 (5.2%) had triple negative disease. Patients with triple negative disease were more likely to have poorly differentiated histology (66.7%), lymphovascular invasion (73.3%), stage 3 disease (37.8%), undergone mastectomy (68.9%), and positive surgical margins (15.6%). On Cox multivariate regression, those with triple negative disease had worse overall survival (hazard ratio [HR] 7.28, P < 0.001). Other adverse prognostic factors included African-American descent (HR 2.24, P = 0.018), comorbidity score of 1 (HR 2.50, P = 0.011), comorbidity score ≥2 (HR 3.27, P = 0.06), and ≥3 positive lymph nodes (HR 3.23, P = 0.007). Similar to invasive ductal carcinoma, triple negative disease in IMPC results in worse survival outcomes. This is the largest and first study to characterize molecular status (including HER2 status) in patients with IMPC and its impact on survival outcomes.

High Expression of Plakoglobin Promotes Metastasis in Invasive Micropapillary Carcinoma of the Breast via Tumor Cluster Formation

Invasive micropapillary carcinoma of the breast (IMPC) is a rare subtype of breast cancer that has a high frequency of lymph node (LN) involvement and metastasis to distant organs. IMPC is characterized by distinct histomorphology and unfavorable prognosis when compared with invasive ductal carcinoma no special type (IDC-NST). However, the underlying molecular mechanisms remain unclear. We reported here that plakoglobin, as a key component in cell adhesion, can promote collective metastasis through facilitating IMPC clusters formation. In comparing the clinicopathological features of 451 IMPC patients and 282 IDC-NST patients, our results showed that tumor emboli were significantly higher in IMPC patients and were associated with a high frequency of metastasis. Both in vitro and in vivo data showed overexpression of plakoglobin in both the cell membrane and the cytoplasm of IMPC clusters. When plakoglobin was knocked down in IMPC cell models, the tumor cell clusters were depolymerized. Using mouse models, we validated the metastatic potential of tumor clusters was higher than single cells in vivo. Further analysis showed that higher expression of plakoglobin was able to promote activation of the PI3K/Akt/Bcl-2 pathway, which might protect the clusters from anoikis. Our data indicate that plakoglobin promotes tumor cluster formation in IMPC and downregulates apoptosis in the cell clusters through activation of PI3K/Akt/Bcl-2 signaling. These results provide a convincing rationale for the high metastatic propensity seen in IMPC.

Breast Carcinoma: Updates in Molecular Profiling 2018

The most significant contribution of molecular subtyping of breast carcinomas has been the identification of estrogen-positive and estrogen-negative tumor subtypes. Knowledge of genetic alterations in these tumors will help clinicians identify novel therapeutic targets. Understanding the progression pathways involved in the transition of in situ carcinoma to invasive carcinoma might lead to efficient risk stratification in these patients. The Cancer Genome Analysis Network has collected genomic and epigenomic data to provide comprehensive information regarding carcinogenesis and pathway interactions. Such information improves understanding of the disease process and also provides more accurate information toward identifying targetable mutations for treatment.

CD1d- and PJA2-related immune microenvironment differs between invasive breast carcinomas with and without a micropapillary feature

Background

Invasive micropapillary carcinoma (IMPC) of the breast is characterized by its unique morphology and frequent nodal metastasis. However, the mechanism for development of this unique subtype has not been clearly elucidated. The aim of this study was to obtain a better understanding of IMPC.

Methods

Using representative cases of mixed IMPC, mRNA expression in the micropapillary area and usual invasive area was compared. Then, immunohistochemical analyses for 294 cases (76 invasive carcinomas with a micropapillary feature [ICMF] and 218 invasive carcinomas without a micropapillary feature [ICNMF]) were conducted. Clinicopathological analyses were also studied.

Results

DNA microarray analyses for mixed IMPC showed that BC-1514 (C21orf118) was commonly upregulated in the micropapillary area. CAMK2N1, CD1d, PJA2, RPL5, SAMD13, TCF4, and TXNIP were commonly downregulated in the micropapillary area. Immunohistochemically, we confirmed that BC-1514 was more upregulated in ICMF than in ICNMF. CD1d and PJA2 were more downregulated in ICMF than ICNMF. All patients with cases of PJA2 overexpression survived without cancer recurrence during the follow-up period, although the differences for disease-free (p = 0.153) or overall survival (p = 0.272) were not significant.

Conclusions

The CD1d- and PJA2-related tumour microenvironment might be crucial for IMPC. Further study of the immune microenvironment and micropapillary features is warranted.

The Impact of Micropapillary Component Ratio on the Prognosis of Patients With Invasive Micropapillary Breast Carcinoma

Background and Objectives: Invasive micropapillary carcinoma (IMPC) of the breast is a rare and aggressive variant of invasive ductal carcinoma characterized by high-grade lymphovascular invasion and high rates of nodal metastasis. The prognostic significance of the micropapillary component (MC) ratio that constitutes this aggressive variation is controversial. In this study, we aimed to investigate the effect of the MC ratio on the prognosis of these patients. Methods: The data of 47 patients with IMPC were retrospectively reviewed. Patients were divided into two groups: MC ratio of 10-75% (Group 1) and greater than 75% (Group 2). The demographic characteristics of the patients, histopathologic features of the tumors, and survival rates were compared. Results: We detected no significant difference in demographic characteristics between groups 1 and 2 (p = 0.21). No significant difference was detected in terms of tumor diameter, lymph node metastasis, lymphovascular invasion, histologic grade, multicentricity, local recurrence, distant metastasis, and overall survival. Conclusion: In the micropapillary subgroup of invasive ductal carcinoma, although positive receptor characteristics are directly proportional to the increase in MC ratio, recurrence and survival rates are not affected by micropapillary component level.

Characteristics of Special Type Breast Tumors in Our Center

Objective

Breast cancer is a heterogeneous disease with different histological types. Ductal breast cancer constitutes the vast majority of the breast cancers. However limited data are present in the rest of breast cancers called special or rare type breast cancers. Here in this study, we tried to describe the clinical features of special type breast cancers in our center.

Materials and Methods

Retrospective descriptive study was performed in Kocaeli University School of Medicine, Department of General Surgery between January 2000 and January 2016. Women diagnosed with primary breast cancer other than ductal carcinoma were included to the study. In total, 101 patients were evaluated according to histologic types, molecular types, Tumor Node Metastasis (TNM) stages, and grades. Survival of the patients was also evaluated.

Results

Medullary and metaplastic types showed basal type; tubular, mucinous, micropapillary carcinoma, cribriform, lobular and apocrine tumors showed luminal type molecular pattern. Neither the existence of ductal carcinoma nor any histologic types had any effects on survival. Apocrine tumors were presented in younger ages.

Conclusion

Histologic types of breast cancer are closely related with the molecular types of the breast cancer. Tumor size, grade, stage of the disease can show differences among histological types which might be due to the genetic background, late onset or limited number of patients. In order to achieve more significant results, multicenter national studies are needed.

Invasive micropapillary carcinoma of the breast has a better long-term survival than invasive ductal carcinoma of the breast in spite of its aggressive clinical presentations: a comparison based on large population database and case-control analysis

There are controversies in the comparison of overall survival between invasive micropapillary carcinoma of the breast (IMPC) and invasive ductal carcinoma (IDC). The objective of this study was to compare the long‐term survival outcome between non‐metastatic IMPC and IDC. The Surveillance, Epidemiology, and End Results database was searched to identify women with non‐metastatic IMPC and IDC diagnosed between 2001 and 2013. Comparisons of patient and tumor characteristics were performed using Pearson's chi‐square. The propensity score matching method was applied with each IMPC matched to one IDC. Breast cancer‐specific survival (BCSS) and overall survival (OS) were estimated using the Kaplan–Meier product limit method and compared across groups using the log‐rank statistic. Multivariate analysis was performed through Cox models. IMPC was presented with aggressive clinical presentations such as larger tumor, more positive lymph nodes, and more advanced stage compared with IDC. A higher rate of estrogen receptor (ER)/progesterone receptor (PR) positivity was also observed in IMPC. With a median follow‐up of 64 months, IMPC had a better BCSS (P = 0.031) and OS (P = 0.012) compared with IDC. In a case–control analysis IMPC was still an independent favorable prognostic factor for BCSS (HR = 0.410, P < 0.001, 95% CI: 0.293–0.572) and OS (HR = 0.497, P < 0.001, 95% CI: 0.387–0.637). In subgroup analysis, IMPC always showed a better survival outcome compared with IDC except in AJCC stage I and histologic grade I disease. IMPC has a better long‐term survival outcome compared with IDC in spite of its highly aggressive clinical presentation.

Invasive micropapillary carcinoma of the mammary gland in humans and canines: Clinicopathological, immunophenotypical and survival approaches

Invasive micropapillary carcinoma (IMPC) is a breast cancer with a proclivity for lymph node metastasis that affects women. In canines, this carcinoma has only recently been reported and appears to have similar histological aspects as its human counterpart. Thus, the aim of the present study was to compare clinicopathological, immunohistochemical and prognostic characteristics of mammary IMPC between humans and canines. In canines, regional metastasis was more frequently observed. Histopathologically, humans and canines predominantly showed a moderate histological grade. The pure subtype and neoplastic emboli were more frequently observed in canines. Regarding immunohistochemical evaluation, most canine and human IMPCs were positive for the estrogen and progesterone receptors. A reversed pattern of epithelial membrane antigen expression and a high proliferation index predominated in both species. The mortality due to the neoplastic disease was more frequently observed in canines (94%) than in humans (4%). Thus, canine IMPCs show a larger tumor size and higher rates of the pure subtype, regional metastasis and mortality than their human counterparts and appear to provide a good spontaneous model for achieving a better understanding of the biological behavior of human IMPCs.

Invasive Micropapillary Carcinoma of the Breast: Immunophenotypic Analysis and Role of Cell Adhesion Molecules (CD44 and E-Cadherin) in Nodal Metastasis

Invasive micropapillary carcinoma is a morphologically distinct subtype of breast carcinoma with high frequency of lymph node metastasis. In this study, we analyzed clinicopathologic features, immunophenotype, and expression of adhesion molecules [CD44 and E-cadherin (E-Cad)] in pure invasive micropapillary carcinoma of the breast. All cases had diffuse micropapillary pattern and were grade II tumors. Lymphovascular emboli were present in 80% and lymph node tumor deposits were seen in 69.2% cases. The cases were classified as; luminal A (11 cases), luminal B (8 cases), Her-2-neu overexpressing (4 cases), and triple negative (2 cases). All cases were positive for luminal cytokeratin (CK)CK8/18, and 2 cases showed <10% positivity for CK5/6. Eighteen cases showed loss of CD44 expression and 7 cases showed only weak positivity. Seven cases with lymph node metastasis showed reexpression of CD44 at metastatic site. Strong to moderate expression of E-Cad was observed in all cases and the corresponding nodal metastasis. To conclude, the loss of the CD44 expression plays role in lymphovascular permeation and metastasis and it can be hypothesized that its reexpression at metastatic site may play a role in homing of tumor cells. However, intact E-Cad expression could be because of the fact that tumour cells travel as clusters and retain their expression of E-Cad.

Comparison of invasive micropapillary and triple negative invasive ductal carcinoma of the breast

BACKGROUND

Invasive micropapillary carcinoma (IMPC) of the breast and triple negative breast cancer (TNBC) are both aggressive subtypes, but little information is available on their comparison.

PATIENTS AND METHODS

Retrospective analysis of 95 IMPC and 200 TNBC-IDC (invasive ductal carcinoma) was conducted to compare the clinicopathologic characteristics and survivals.

RESULTS

For IMPC, pN was the independent prognostic factor of local-regional recurrence free survival (LRRFS) (P = 0.045) and metastasis free survival (MFS) (P = 0.048), but not of overall survival (OS) (P = 0.165). For TNBC, pT and lymphovascular invasion (LVI) were both independent prognostic factors of MFS (pT: P = 0.006, LVI: P = 0.010) and OS (pT: P = 0.006, LVI: P = 0.001), but not for LRRFS (pT: P = 0.060, LVI: P = 0.503). IMPC exhibited more aggressive features than TNBC, including larger tumor size, a greater proportion of nodal involvement, and an increased incidence of LVI. After a median follow-up duration of 61 months, 5y-LRRFS rate was lower in IMPC than in TNBC, in entire cohort (71.4 ± 4.8% vs. 89.8 ± 2.2%, P < 0.001) and in node positive cases (64.2 ± 5.9% vs. 81.7 ± 4.4%, P = 0.048). A tendency of lower 5y-MFS rate was observed in TNBC compared with in IMPC, in node positive cases (63.8 ± 5.5% vs. 74.8 ± 5.5%, P = 0.053) and in node negative cases (80.1 ± 3.6% vs. 96.2 ± 3.8%, P = 0.052), but it did not reach significance. 5y-OS was similar between IMPC and TNBC (81.9 ± 4.7% vs. 79.8 ± 3.1%, P = 0.475).

CONCLUSIONS

IMPC is featured with high rate of lymph node involvement which is strongly associated with high rate of LRR. TNBC is featured with high rate of early distant metastasis without increase of nodal metastases. The survival is still relatively poor even in node negative cases.

Similar prognoses for invasive micropapillary breast carcinoma and pure invasive ductal carcinoma: a retrospectively matched cohort study in China

PURPOSE

Invasive micropapillary breast carcinoma (IMPC) is a rare pathological finding. Few studies have compared IMPC with invasive ductal breast carcinoma (IDC) according to matched nodal status and age. To better illustrate the difference between IMPC and IDC prognoses, we conducted this cohort study.

METHODS

51 mixed or pure IMPC patients and 102 pure IDC patients were matched for nodal status and age. Clinical and biological features as well as disease-free survival (DFS) were compared between groups.

RESULTS

More than one-half of IMPC consisted of mostly or exclusively IMPC component (meaning greater than 75%) and these tumors significantly correlated with a higher histologic grade (P = 0.016) and LVI positivity (P = 0.036) compared with mixed IMPC. IMPC displayed a significantly higher rate of estrogen receptor (ER) positivity and lymphovascular invasion (LVI) compared to matched IDC. Women diagnosed with IMPC had a slight, but not significant, reduced frequency for recurrence and metastasis compared to women with IDC (15.7% vs. 21.6%, P = 0.518). In the subgroup analysis, IMPC patients demonstrated significantly reduced survival (P = 0.018) compared to IDC patients in the T1N2-3 subpopulation, whereas IDC patients demonstrated significantly increased recurrence and metastasis (P = 0.024) compared to IMPC patients in the T2N2-3 subgroup. No difference was observed in patients with 3 or less positive lymph nodes (LNs).

CONCLUSION

Although no difference in DFS was observed between IMPC and LN-matched IDC patients, IMPC patients demonstrated a significantly poorer outcome compared to IDC patients with smaller tumors and 4 or more positive LNs. The opposite results were observed in larger tumors and patients with 4 or more positive LNs. Therefore, we might advise more proactive treatment for IMPC patients with a smaller tumor size and extensive LN involvement. Furthermore, correlative IMPC studies should focus on this subset of patients to elucidate the genetic and/or biologic differences that contribute to metastatic potential.

Breast carcinoma: molecular profiling and updates

The most significant contribution of molecular subtyping of breast carcinomas has been the identification of estrogen-positive and estrogen-negative tumor subtypes, which are 2 distinct entities with differing prognoses and requiring different therapy. Molecular and genetic analyses can provide prognostic information; however, a thorough histopathologic evaluation with an evaluation of predictive biomarkers will provide similar information. Knowledge of genetic alterations in these tumors will help identify novel therapeutic targets, which might have an impact on prognosis. Understanding the progression pathways involved in the transition of in situ carcinoma to invasive carcinoma might lead to efficient risk stratification in these patients.

Population-based comparison of prognostic factors in invasive micropapillary and invasive ductal carcinoma of the breast

Background:

Invasive micropapillary carcinoma (IMPC) is a variant of breast carcinoma with a higher propensity for lymph node metastases compared with invasive ductal carcinoma (IDC).

Methods:

Retrospective analysis of 636 IMPC and 297 735 IDC cases in the Surveillance, Epidemiology and End Results database comparing disease-specific survival (DSS) and overall survival (OS) between IMPC and IDC.

Results:

A higher percentage of IMPC cases (52.0%) had nodal metastases compared with IDC cases (34.6%). The 5-year DSS and OS for IMPC was 91.8% and 82.9%, respectively compared with 88.6% and 80.5% for IDC, respectively. For both IMPC and IDC, oestrogen-receptor positivity was associated with better survival, while having four or more positive lymph nodes or larger tumour size correlated with worse survival. Radiotherapy provided a survival benefit for both histological types.

Conclusions:

Despite IMPC's higher propensity for lymph node metastasis, IMPC has DSS and OS that compare favourably with IDC.

Histopathological and immunohistochemical assessment of invasive micropapillary mammary carcinoma in dogs: a retrospective study

Invasive micropapillary carcinoma (IMPC) of the mammary gland, despite its rare occurrence in humans and dogs, is an important neoplasm due to its aggressive behaviour. The aim of this study was to evaluate the clinicopathological and immunophenotypical characteristics of IMPC and to determine the overall survival of dogs with this tumour. Of the selected cases, the majority had >3 cm neoplasms (15/19, 78.95%) and lymph node metastases (16/16, 100%), but only two cases (2/9, 22.2%) had distant metastases. The IMPCs were classified as either pure (15/22, 68.18%) or mixed (7/22, 31.82%) types. There was a predominance of moderate histological grade tumours (16 grade II) and the average overall survival was 120 days. Positive immunohistochemical staining for epithelial membrane antigen and negative staining for CD-31, p63 and cytokeratin (CK) AE1AE3 in cystic formations confirmed the micropapillary nature of these neoplasms. A proportion of cases exhibited positive epithelial staining for p63 (4/20, 20%) and CK34βE12 (20/22, 90.9%). Most cases were positive for oestrogen (19/20, 95%) and progesterone (19/20, 95%) receptors, but lacked HER-2 (16/22, 72.72%) and epidermal growth factor receptor (15/22, 68.18%) over-expression. The mean proliferation index was 14.8%. The findings demonstrate that, similar to humans, canine IMPCs behave aggressively with high rates of metastasis to regional lymph nodes and short overall survival times.

Recurrence of invasive micropapillary carcinoma of the breast with different ultrasound features according to lesion site: case report

Invasive micropapillary carcinoma (IMPC) of the breast is a distinct variant of breast cancer. Extensive lymphatic penetration, lymph node metastasis, and local recurrence are seen at a relatively high frequency. On ultrasound (US) findings, IMPC has been reported to be an irregular or lobulated mass with hypoechoic internal areas, but as yet there is no consensus regarding typical findings. A 52-year-old female noticed a mass less than 3 cm in diameter in her left upper breast. US findings indicated an irregularly shaped, hypoechoic tumor with indistinct margins. The diagnosis according to fine-needle aspiration cytology was invasive ductal carcinoma. She underwent lymph node dissection with mastectomy of the left breast. Histological examination revealed mixed-type IMPC. Three years and three months after surgery, IMPC recurred under the skin of the surgical scar. US findings indicated a hyperechoic tumor in this region. Eight months after further surgery, a tumor in the anterior chest wall was observed. US findings indicated an oval hypoechoic tumor with posterior acoustic enhancement. US findings differed between primary and recurrent IMPC because of differences in the occupancy and distribution of IMPC. We describe here a comparison between US and histological findings, as well as differences in IMPC between primary, secondary and tertiary sites.

Metaplastic variant of invasive micropapillary breast carcinoma: a unique triple negative phenotype

Invasive micropapillary carcinomas (IMC) and metaplastic breast carcinoma (MBC) have different clinicopathologic features. This study reports an unusual case of multifocal grade III IMC associated with MBC component in a 35-year-old woman. MBC was vimentin positive, pancytokeratin negative, and showed focal p63 positivity. Immunostains for estrogen and progesterone receptor, and fluorescence in situ hybridization for Her2/neu amplification were negative. All the left axillary lymph nodes dissected were positive for metastatic carcinoma with ductal and IMC patterns, but without metaplastic component. Postmastectomy computed tomography and magnetic resonance imaging scans showed metastases to lungs, liver, brain, and vertebrae. The biologic behavior of tumor was in accordance with histology, so that the nodal and distant metastases were testament to the underlying inherently aggressive IMC, whereas large tumor size and triple negativity reflected the features of MBC. To the best of the authors' knowledge, this is the first report of a metaplastic variant of invasive micropapillary breast carcinoma with triple negative phenotype.

Cutaneous invasive micropapillary carcinoma of probable apocrine sweat gland origin in a cat

An invasive micropapillary carcinoma (IMC) occurred in the buccal skin of an 18-year-old female cat. Histologically, the tumor had a honeycomb pattern characterized by clusters of neoplastic epithelial cells that were surrounded by empty clear spaces and lined with fibrocollagenous stroma. On immunohistochemistry, the neoplastic cells were positive for cytokeratin (clone CAM5.2; pancytokeratin, clone AE1/AE3) and carcinoembryonic antigen (CEA) but negative for cytokeratin 14, vimentin, S100, smooth muscle actin, and p63. The CEA-positive staining reaction was present along the outermost rim of the neoplastic cell clusters consistent with an "inside-out" immunoreactivity pattern. Examination of the tumor cells by electron microscopy revealed microvilli on the outermost rim of neoplastic cells that were directed toward the surrounding vacant space. Based on histomorphological characteristics, the neoplasm was defined as an IMC of "pure-type." The location site and immunohistochemical features suggest the tumor was most likely derived from the apocrine sweat glands in the buccal skin.