Invasive mammary carcinoma with neuroendocrine differentiation: histological features and diagnostic challenges

Histopathological Features Predicting Neuroendocrine Morphology in Primary Breast Tumors: A Retrospective Analysis

Objective

Neuroendocrine neoplasms of primary breast tumors are rare compared to locations, such as the respiratory system and gastrointestinal system, where they are frequently observed. The diagnostic criteria for primary neuroendocrine tumors of the breast have been changed since first description. Morphological and immunohistochemical features helpful in their diagnosis, which vary due to the heterogeneous nature of these tumors, are highlighted in this retrospective study. The purpose was to determine specific histopathological features that can identify neuroendocrine morphology in primary breast tumors.

Materials and Methods

Cases diagnosed with invasive breast carcinoma from resection materials in a single center between 2011 and 2022 and in which neuroendocrine markers were investigated were included. Demographic information, initial histopathological diagnosis, presence of tumor in another organ, tumor location, size and surgical details of the cases were obtained from the hospital database and pathology reports. The slides were re-evaluated in terms of tumor growth pattern, cribriformity, tubule formation, nuclear features, prominence of nucleoli, palisading and basal location of nuclei, presence of grooves, cytoplasmic features and evidence of cytoplasmic border.

Results

The presence of basally located nuclei, absence of tubule formation, inconspicuous nucleoli, fine nuclear chromatin, granular cytoplasm and inconspicuous cytoplasmic borders were frequent findings in tumors with neuroendocrine features (p<0.05). These features may help differentiate primary breast tumors with neuroendocrine features from other breast carcinomas.

Conclusion

The histopathological features that are different from the specific features seen in classical neuroendocrine tumors, the absence of specific clinical and radiological findings, the inability to study neuroendocrine markers in every laboratory and the need to prove that the breast tumor is not a metastasis all create diagnostic difficulties for primary breast neuroendocrine neoplasms. We believe that the results of this study may help diagnose and identify more specific histomorphological features that help determine neuroendocrine morphology in primary breast tumors.

Expression of neuroendocrine markers predicts increased survival in triple-negative breast cancer patients

Background

The significance of neuroendocrine (NE) markers in triple-negative breast cancer (TNBC) patients has not been investigated. This study aims to clarify the incidence and prognostic significance of NE marker expression in TNBC, determine its association with other clinicopathological parameters, and further explore the pathological features and potential treatment options for TNBC patients expressing NE markers.

Methods

Clinicopathological data were collected from 396 TNBC patients undergoing radical breast cancer surgery at Peking Union Medical College Hospital from January 2002 to December 2014, with a final follow-up in July 2019. Immunohistochemistry (IHC) staining was performed for NE markers including chromogranin A (CgA) and synaptophysin (Syn). For TNBC patients with positive NE marker expression, IHC staining was then performed for alpha-thalassemia/mental retardation X-linked (ATRX), O(6)-methylguanine-methyltransferase (MGMT), somatostatin receptor 2 (SSTR2), and programmed death receptor-ligand 1 (PD-L1). The chi-square or Fisher exact test was used to evaluate the correlations between NE marker expression and other parameters. Survival curves were plotted using the Kaplan-Meier (K-M) method to assess the prognostic significance of NE markers in TNBC.

Results

NE marker-positive staining was observed in 7.6% (30/396) of all TNBC cases. Only 0.5% (2/396) cases had ≥ 90% neoplastic cells expressing NE markers. Positive NE marker expression was associated with negative basal-like marker expression. K-M survival analysis showed that the NE marker-positive TNBC patients had higher disease-free survival (DFS) rates than the NE marker-negative patients at the same stage. Among the 30 NE marker-positive TNBC cases, 13.3% and 26.7% showed negative IHC staining for ATRX and MGMT, respectively, while 13.3% had a 3+ score for SSTR2 IHC staining. For PD-L1 IHC staining, 13.3% of the 30 TNBC cases were higher than 10 scores in Combined Positive Score (CPS), and 10.0% were higher than 10% in Tumor Cell Proportion Score (TPS).

Conclusion

There was a small proportion of TNBC patients expressing NE markers. TNBC patients with positive NE marker expression had a better prognosis than the negative group at the same stage. TNBC cases with positive NE marker expression may potentially benefit from immunotherapy or somatostatin analogue treatment.

Defining triple-negative breast cancer with neuroendocrine differentiation (TNBC-NED)

Primary breast neuroendocrine (NE) neoplasms are uncommon, and definitions harbor controversy. We retrospectively collected 73 triple-negative breast cancers (TNBC) and evaluated NE biomarker expression along with p53 aberrant staining (which correlates with TP53 gene mutation) and Rb protein loss by immunohistochemistry. In the study cohort, we found 11 (15%) cases of TNBC with neuroendocrine differentiation (TNBC-NED) showing positivity for one or more NE markers (synaptophysin/chromogranin/insulinoma-associated protein 1 [INSM1]). We also identified one separate small cell neuroendocrine carcinoma. Histologic types for these 11 TNBC-NED cases were as follows: 8 invasive ductal carcinoma (IDC) not otherwise specified (NOS), 2 IDC with apocrine features, 1 IDC with solid papillary features. INSM1 had the highest positivity and was seen in all 11 carcinomas. Seven (64%) cases showed p53 aberrant staining, 6 (55%) had Rb protein loss, while 6 (55%) had p53/Rb co-aberrant staining/protein loss. TNBC-NED was associated with Rb protein loss (p < 0.001), as well as p53/Rb co-aberrant staining/protein loss (p < 0.001). In 61 cases negative for NE markers, 37 (61%) showed p53 aberrant staining, while 5 (8%) had Rb protein loss. We also analyzed genomic and transcriptomic data from The Cancer Genome Atlas (TCGA) PanCancer Atlas of 171 basal/TNBC patients. Transcriptomic analysis revealed mRNA expression of RB1 to be correlated negatively with SYN1 mRNA expression (p = 0.0400) and INSM1 mRNA expression (p = 0.0106) in this cohort. We would like to highlight the importance of these findings. TNBC-NED is currently diagnosed as TNBC, and although it overlaps morphologically with TNBC without NED, the unique p53/Rb signature highlights a genetic overlap with NE carcinomas of the breast.

Expression of novel neuroendocrine markers in breast carcinomas: a study of INSM1, ASCL1, and POU2F3

INSM1, ASCL1, and POU2F3 are novel transcription factors involved in neuroendocrine (NE) differentiation of neoplasms in several organs, but data on their expression in breast carcinomas (BCs) are limited. We retrospectively evaluated the expression of these markers in a series of 97 BCs (58 with NE morphology and 39 with otherwise uncommon morphology) tested prospectively using immunohistochemistry (IHC). Nuclear staining in >50% of the cells was used as the positive cut-off. Thirty-two of the 97 BCs (33%) were INSM1-positive. INSM1-positivity correlated significantly with histologic type and presence of stromal mucin. INSM1 also correlated with synaptophysin and chromogranin, established markers of NE differentiation (P < .0001 and P = .0023, respectively). In BC with NE morphology, the expression of INSM1 supported NE differentiation, and INSM1 was more specific than synaptophysin and more sensitive and specific than chromogranin. INSM1 was the most expressed NE marker in 17 BCs. INSM1-positive BCs included 56% of solid papillary BCs, 88% of BCs with solid papillary features, and 75% of high-grade NE carcinomas. Of 35 BCs tested for POU2F3 and ASCL1, only 1 and 4 cases were positive, respectively. Our results show that INSM1 is a sensitive marker of NE differentiation in BC and should be included with synaptophysin and chromogranin in the IHC panel used to evaluate NE differentiation in BC with NE morphology. ASCL1 and POU2F3 are uncommon in BC and their routine assessment is not warranted.

Invasive ductal carcinoma of breast with neuroendocrine differentiation: A case report

Primary invasive breast carcinoma with neuroendocrine differentiation is an uncommon presentation. We hereby report a case diagnosed as invasive ductal carcinoma with neuroendocrine differentiation in a 52‐year‐old female patient who presented with a painless right breast lump.

Primary invasive breast carcinoma with neuroendocrine differentiation is an uncommon presentation. We hereby report a case of invasive ductal carcinoma with neuroendocrine differentiation who presented with a painless right breast lump. The patient was evaluated with mammography, ultrasound‐guided tru‐cut biopsy, and CT scan of the chest. Later right mastectomy with frozen section examination of right axillary sentinel lymph node was performed. Finally, a diagnosis of invasive ductal carcinoma with neuroendocrine differentiation was made with the help of the histomorphological evaluation and immunohistochemical study using neuroendocrine markers like CD56 and INSM1. To the best of our knowledge, this is the first case of invasive breast carcinoma with neuroendocrine differentiation reported from Nepal and can help better understand the clinical entity, diagnosis, treatment, and prognosis of this rare tumor.

Primary Neuroendocrine Tumor of the Breast: Current Understanding and Future Perspectives

Primary neuroendocrine carcinoma of the breast (NECB) is characterized with heterogeneity, rarity, and poor differentiation, which is probably an underestimated subtype of breast cancer, including small cell NECs and large cell NECs. The diagnostic criteria for NECB have been constantly updated as the disease changes and the understanding increases. According to the latest WHO Classification, primary neuroendocrine neoplasm (NEN) of the breast consists of well-differentiated neuroendocrine tumors (NET), extremely aggressive neuroendocrine carcinomas (NEC) as well as invasive breast cancers of no special type (IBCs-NST) with neuroendocrine differentiation. The accurate diagnosis of NECB remains a challenge for its low incidence, which needs multi-disciplinary methods. For the rarity of the disease, there is a lack of large samples and prospective clinical research. For these invasive tumors, there are no standardized therapeutic guidelines or norms, and the treatment often refers to nonspecific breast cancer. In addition, the prognosis of such patients remains unknown. In 2003, the World Health Organization (WHO) listed NECB as an independent entity for the first time, while few features of NECB were clarified. In this review, it presents the WHO Classification, clinicopathologic characteristics, diagnosis, treatment, and prognosis of these patients. In addition, it summarizes the latest studies on molecular features of NECB, aiming to provide new therapeutic perspectives for the disease.

Primary neuroendocrine carcinomas of the breast and neuroendocrine differentiated breast cancers: Relationship between histopathological and radiological features

PURPOSE

The aim of this study wasto investigate whole-breast imaging findings (mammography, ultrasonography (US), magnetic resonance imaging (MRI),clinical, and histopathological findings of primary neuroendocrine carcinomas of the breast (NEC) and neuroendocrine differentiated breast cancers (NEBC).

METHODS

Patients withadiagnosis of breast cancer with histopathological neuroendocrine features between the years 2010 and 2021 were retrospectively screened.The lesions were divided into two main groups depending on staining with neuroendocrine markers (synaptophysin and chromogranin A). Those showing focal staining were categorized as NEBC while those with diffuse staining as NEC.The mammography, US, and MRI of the lesionswere reviewed in consensus by two breast radiologists in order to assess imaging featuresretrospectively according to the Breast Imaging Reporting and Data System (BI-RADS) 5th lexicon.The findings were compared with breast cancers without neuroendocrine features (BC-WNE) which were randomly selected from the same database.

RESULTS

A total of 105 lesions [NEBC (n = 44), NEC(n = 11), BC-WNE (n = 50)] were evaluated.Patients with neuroendocrine tumors were older (p < 0.001) than those with BC-WNE. Compared with BC-WNE tumors, radiological findings typical of malignancy such as irregular shape [NEBC (7/20); NEC(3/7) vs BC-WNE (35/43); p < 0.001], spiculation [NEBC (2/20); NEC(0/7) vs BC-WNE (21/43); p < 0.001], architectural distortion [(NEBC (3/24); NEC(0/9) vs BC-WNE (31/50); p < 0.001)], calcification [(NEBC (6/24), NEC(0/9) vs BC-WNE (n = 27/50); p = 0.001)] on mamography, non-parallel orientation to skin [(NEBC (n = 17/29), NEC(n = 4/9), BC-WNE (n = 35/42); p = 0.008)], acoustic shadowing [(NEBC (n = 12/29), NEC(1/9), BC-WNE (n = 29/42); p = 0.009)], axillary lymphadenopathy [(NEBC(n = 3/30), NEC(n = 1/9), BC-WNE (21/50); p < 0.001)]on US were less common features of the neuroendocrine carcinomas of breast. Aside from shape features, there was no significant difference in contrast pattern (p = 0.866), kinetic curve (p = 0.454) and diffusion restriction (p = 0.242) on MRI.

CONCLUSION

Characteristic malignant imaging features, including irregular shape, spiculated margins, suspicious calcifications, and posterior acoustic shadowing, are uncommon in neuroendocrine carcinomas of breast. These carcinomas tend to show more benign imaging features when compared with BC-WNE.

Neuroendocrine neoplasms of the breast: diagnostic agreement and impact on outcome

The classification of breast neuroendocrine neoplasms (Br-NENs) was modified many times over the years and is still a matter of discussion. In the present study, we aimed to evaluate the diagnostic reproducibility and impact on patient outcomes of the most recent WHO 2019 edition of breast tumor classification, namely, for neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs). This multicentric observational study included 287 breast neoplasms with NE differentiation. The cases were blindly classified by three independent groups of dedicated breast and/or endocrine pathologists following the 2019 guidelines. Diagnostic concordance and clinical impact were assessed. We observed only a moderate overall diagnostic agreement across the three centers (Cohen's kappa 0.4532) in distinguishing NET from solid papillary carcinomas (SPCs) and no special type carcinomas (NST) with NE differentiation. Br-NENs were diagnosed in 122/287 (42.5%) cases, subclassified as 11 NET G1 (3.8%), 84 NET G2 (29.3%), and 27 NEC (9.4%), the latter group consisting of 26 large-cell and 1 small-cell NECs. The remaining 165/287 (57.5%) cases were labeled as non-NEN, including SPC, mucinous, NST, and mixed NE carcinomas. While NET and non-NEN cases had a comparable outcome, the diagnosis of NECs showed negative impact on disease-free interval compared to NETs and non-NENs (p = 0.0109). In conclusion, the current diagnostic classification of Br-NENs needs further adjustments regarding morphological and immunohistochemical criteria to increase the diagnostic reproducibility among pathologists. Our data suggest that, apart from high-grade small- and large-cell NECs, Br-NENs behave like non-NEN breast carcinomas and should be managed similarly.

Neuroendocrine Neoplasms of the Breast: The Latest WHO Classification and Review of the Literature

Simple Summary

Breast tumors exhibiting neuroendocrine differentiation are a heterogeneous group of tumors that have been variously defined in previous World Health Organization (WHO) classifications. In the WHO Classification of Tumours, 5th edition, neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs) of the breast, both of which are invasive cancers, are classified as neuroendocrine neoplasms (NENs) of the breast. However, the clinical significance of NE differentiation in breast cancers, especially in NETs of the breast, is not yet fully understood, and a large overlap appears to exist between breast cancers showing NE differentiation and invasive breast cancer of no special type (IBC-NST). While breast NECs show distinct clinical and morphological features, diagnosis of NETs based on the morphological characteristics alone can be challenging; one reason is that breast NETs do not necessarily have the same morphological characteristics as those of NENs arising in other organs. Thus, the heterogeneity of breast tumors with neuroendocrine differentiation and the changes in their classifications over the years have left many open issues that still need to be resolved. In this review, we shall summarize the history of breast “NENs,” including of mixed types of tumors and the characteristics of these tumors, and discuss their differences from NENs arising in other organs.

Abstract

Breast tumors with neuroendocrine (NE) differentiation comprise an uncommon and heterogeneous group of tumors, including invasive breast cancer of no special type (IBC-NST) with NE features, neuroendocrine tumors (NETs), and neuroendocrine carcinoma (NEC). The most recent World Health Organization (WHO) classification in 2019 defined neuroendocrine neoplasms (NENs) of the breast (Br-NENs) as tumors in which >90% of cells show histological evidence of NE differentiation, including NETs (low-grade tumors) and NEC (high-grade). Due to the low prevalence of these tumors and successive changes in their diagnostic criteria over the years, only limited evidence of these tumors exists, derived mainly from case reports and retrospective case series. Breast tumors with NE differentiation are usually treated like the more commonly occurring IBC-NSTs. Immunohistochemistry (IHC) of breast tumors with NE differentiation usually shows a hormone receptor (HR)-positive and human epidermal growth factor type 2 (HER2)-negative profile, so that hormonal therapy with cyclin-dependent kinase (CDK)4/6 inhibitors or other targeted agents would be reasonable treatment options. Herein, we present a review of the literature on breast tumors with NE differentiation as defined in the latest WHO 2019 classification, and discuss the clinical management of these tumors.

INSM1, a Novel Biomarker for Detection of Neuroendocrine Neoplasms: Cytopathologists’ View

Background: Insulinoma-associated protein 1 (INSM1) has been considered as a novel immunostain for neuroendocrine tumors (NETs) and is hypothesized to be more reliable than first-generation NET biomarkers, such as CGA (chromogranin A), SYP (synaptophysin) and CD56 (neural cell adhesion molecule). In this review, we summarize existing literature on INSM1′s reliability as an immunostain for detection of various NETs, its results in comparison to first-generation NET biomarkers, and its expression in both non-NETs and benign tissues/cells on cytology specimens (cell blocks/smears).

The classification of neuroendocrine neoplasms of the breast and its clinical relevance

Neuroendocrine neoplasms of the breast (Br-NENs) are rare tumors of the mammary gland. Their definition and classification have been a matter of discussion for more than half a century, as they present some degree of overlap with other malignancies in the mammary gland. The recent evolutions in the understanding of the pathogenesis of neuroendocrine neoplasms (NENs) as well as the novel tools in the diagnostic arsenal of the pathologists, and a better correlation with clinical data, have led to improved classification schemes for these entities, beginning from those arising in digestive and thoracic organs. These new classification concepts have been recently expanded to NENs arising in every anatomical site, with the proposal of a common classification framework that has been applied in the 5th edition of the WHO classification of tumors. These concepts include the recognition of two distinct families of NENs (neuroendocrine tumors, NETs, and neuroendocrine carcinomas, NECs), the identification of mixed neuroendocrine/non-neuroendocrine neoplasms, and the application of definite morphological and immunohistochemical criteria for the diagnosis of NENs. The last WHO classification of Br-NENs, however, still seems to leave several unanswered questions and unmet needs in the understanding of diagnostic and clinical features of these entities. This review will critically revise the current classification of Br-NENs, underlining its lights and shadows and focusing on the identification of diagnostic histopathological criteria that can help the univocal recognition of Br-NET, Br-NEC, and Br-MiNEN.

Independent primary cutaneous and mammary apocrine carcinomas with neuroendocrine differentiation: Report of a case and literature review

Cutaneous apocrine carcinomas share common features with their counterparts in the breast; hence, metastatic mammary carcinoma must be excluded before such lesions can be designated primary cutaneous neoplasms. Primary tumors from either source rarely exhibit neuroendocrine differentiation. We report a case of a 72-year-old female with a painless 1.2-cm scalp nodule. An incisional biopsy revealed dermal involvement by an invasive apocrine carcinoma juxtaposed to a benign apocrine cystic lesion. Immunohistochemically, the carcinoma expressed neuroendocrine proteins including synaptophysin, chromogranin, and CD56. A primary cutaneous apocrine carcinoma with neuroendocrine differentiation was favored, but additional investigations to exclude breast origin were recommended. These revealed a 1.1-cm nodule in the right breast, which proved to be an invasive ductal carcinoma, morphologically and immunophenotypically similar to the scalp lesion. This confounded the case, yet factors militating against metastatic breast carcinoma to skin included (a) the small size of the mammary tumor, (b) absence of other metastatic disease, and (c) juxtaposition of the scalp carcinoma to a putative benign precursor. Molecular studies were undertaken to resolve the diagnostic quandary. Single nucleotide polymorphism microarray analysis revealed distinct patterns of chromosomal copy number alterations in the two tumors, supporting the concept of synchronous and unusual primary neoplasms.

Breast cancer with neuroendocrine differentiation: an update based on the latest WHO classification

Breast cancers with neuroendocrine (NE) differentiation are very heterogeneous, comprising broadly cancers that are morphologically similar to NE tumors (NET) of other anatomic sites, infiltrating breast carcinomas, no special type (IBC-NST) and other special subtypes with NE morphology and/or NE markers expression. Depending on the classification schemes, they are variably included into "NE breast cancers". The latest WHO classification harmonized NE breast cancers with NE neoplasms (NEN) of other organ systems, defined NEN into well-differentiated NET (low Nottingham grade) and poorly-differentiated NE carcinoma (NEC) (high Nottingham grade). Other IBC with NE differentiation are diagnosed based on solely the non-NEN component. Due to the changes in diagnostic criteria, variable results were obtained in the previous studies on NE breast cancers. Hence, the clinical value of NE differentiation in breast cancers is not well investigated and understood. In this review, the current understanding in the pathogenesis, clinical, prognostic, immunhistochemical, and molecular features of "NE breast cancers" is summarized. Controversial issues in their diagnosis and classification are also discussed.

Neuroendocrine Carcinomas of the Canine Mammary Gland: Histopathological and Immunohistochemical Characteristics

Invasive mammary carcinomas with neuroendocrine differentiation are rare in women and were reported only once in female dogs. For the present study, ten cases of solid mammary carcinoma positive for chromogramin A in immunohistochemistry were selected. Histopathological characteristics of these tumors were described and immunohistochemical evaluation was performed with chromogranin A, synaptophysin, CD56, NSE, PGP 9.5, pancitokeratin, Ki67, estrogen receptor (ER), and progesterone receptor (PR). The average animal age was 13.2 years old and the average tumor size was 4.8 cm. In total, 70% of the neoplasms were classified as grade III and 30% as grade II by the Nottingham histological grade system. High mitotic index was observed with a mean of 27.5 mitoses in 10 high magnification fields. Only one case showed typical carcinoid tumor characteristics. In addition, vascular invasion was shown in 3 tumors. All carcinomas were positive for chromogran A, while only two cases were reactive to synaptophysin. For PGP 9.2, NSE and CD56, we observed positivity of 100, 90, and 70%, respectively, in the samples, being that no tumor was positive for all the neuroendocrine markers. All neoplasms showed ER and PR in at least 10% of neoplastic cells, while Ki67 varied from 29 to 95%, with mean mitotic index of 67%. Four of the ten animals died within 1 year of the tumor diagnosis. Neuroendocrine neoplasms occur in the canine mammary gland and are propably underdiagnosed. This is due to their non-specific morphological characteristics and the low use of neuroendocrine immunohistochemistric markers the diagnostic routine. More studies are necessary to determine the prognosis of this new histological type.

INSM1 is a novel prognostic neuroendocrine marker for luminal B breast cancer

Insulinoma associated protein 1 (INSM1) is a relatively new marker of neuroendocrine differentiation. It has been shown to have a high sensitivity for neuroendocrine tumours arising from different organs. This study evaluated INSM1 as a marker for neuroendocrine differentiation in infiltrating breast cancers (IBC). The expression of INSM1, together with other neuroendocrine markers (synaptophysin, chromogranin and CD56) was assessed in a large IBC cohort using tissue microarray by immunohistochemistry. Overall, 13.1%, 4.6%, 7.0% and 6.5% of the cases were positive for synaptophysin, chromogranin, INSM1 and CD56, respectively. INSM1 expression showed similar clinicopathological and biomarker profiles as chromogranin and synaptophysin. They were associated positively with luminal profile (p<0.001) and hormone receptors expression (p≤0.015), but negatively with HER2 (p≤0.044) and high molecular weight cytokeratins (p≤0.047). Using synaptophysin and/or chromogranin to define neuroendocrine differentiation, INSM1 showed a sensitivity of 37.3%, and was more sensitive than chromogranin (33.5%) and CD56 (16.4%) but less than synaptophysin (94.6%). Interestingly, INSM1 expression segregated IBC with neuroendocrine differentiation into different prognostic subgroups, particularly within luminal B subtype. Among the synaptophysin/chromogranin+ luminal B cancers, INSM1 expression was associated with significantly better survival (DFS: χ²=8.009, p=0.004; BCSS: χ²=3.873, p=0.049). Multivariate analysis showed that synaptophysin/chromogranin+ INSM1- status was an independent adverse factor for DFS (HR=2.282, 95%CI=1.196-4.356, p=0.012) in the luminal B subtype. Our data supported the usefulness of INSM1 in detecting neuroendocrine differentiation in IBC. Furthermore, INSM1 expression suggested a favourable prognostic impact; thus, it could be useful for stratifying neuroendocrine tumours with different prognosis.

Primary neuroendocrine carcinoma of the breast: A case report of liver and lymph node metastases after eight years from diagnosis

Primary neuroendocrine carcinoma of the breast (NECB) is one of the rarest subtypes of breast tumor, and for this reason, there are no data from prospective clinical trials on its optimal management. Its incidence is <0.1% of all breast cancers and <1% of all neuroendocrine tumors. The diagnosis of NECB requires the expression of neuroendocrine markers (chromogranin, synaptophysin, NSE) and the lack of simultaneous neuroendocrine carcinoma in extramammary sites. We present a case of a poorly differentiated neuroendocrine carcinoma (PD-NEC) metastasized in liver and lymph node after eight years. Mammography, ultrasound imaging, CT, and pathology findings are described.

Histopathological and Clinical Differences Between Primary Breast Carcinomas With Neuroendocrine Features and Primary Breast Carcinomas Mimicking Neuroendocrine Features

We aimed to determine the histopathological differences between primary breast carcinomas with neuroendocrine features (NEBC) and carcinomas mimicking neuroendocrine features (NEBC-like). Twenty-three cases with NEBC, all showing positive staining for synaptophysin and/or chromogranin-A in ≥50% of tumor cells and 36 cases with NEBC-like (no staining for neuroendocrine [NE] markers but suspicious for NE morphology in terms of solid/trabecular growth patterns) were included in the study. Significant differences were found between the groups in terms of the patients' ages, histologic/nuclear grade of tumor, lymphovascular invasion, comedo-type ductal carcinoma in situ (DCIS), microcalcification, Ki-67 proliferation index, nuclear shape, and level of peritumoral lymphocytic infiltration. The presence of large-size solid cohesive groups of tumor cells; plasmocytoid, spindle, and/or columnar shapes of tumor cells; and eosinophilic-granular appearance of cytoplasm were mostly noted in the NEBC group. The presence of small- to medium-sized solid cohesive groups of tumor cells; high-grade histologic and nuclear features; clear cytoplasm; and round to ovoid nucleus were mostly noted in the NEBC-like group. No significant differences were found in terms of tumor size, ER/PR/HER2 status, as well as the presence of DCIS, elastosis, extracellular/intracellular mucin, signet ring cells, apocrine features, and accompanying papilloma or ductal ectasia. In conclusion, small- to medium-sized solid cohesive groups of tumor cells, high-grade features, clear cytoplasm, round to ovoid shape of nucleus, lymphovascular invasion, comedo-type DCIS, microcalcification, high level of Ki-67 proliferation index (≥20%), and moderate/strong level of peritumoral lymphocytic infiltration might support non-NE features in breast carcinomas.

Expression of Insulinoma-Associated Protein 1 (INSM1) and Orthopedia Homeobox (OTP) in Tumors with Neuroendocrine Differentiation at Rare Sites

Insulinoma-associated protein 1 (INSM1) and orthopedia homeobox (OTP) are transcription factors that play a critical role in neuroendocrine (NE) and neuroepithelial cell development. INSM1 has been identified in multiple tumors of NE or neuroepithelial origin, whereas OTP expression has been mainly studied in NE tumors of pulmonary origin. Expression of OTP appears to correlate with poorer prognosis in pulmonary carcinoids; however, its expression patterns in other NE/neuroepithelial tumors need further investigation. Here, we assessed the diagnostic utility of INSM1 and OTP in tumors with NE differentiation at relatively uncommon sites including prostate, breast, and tumors of gynecologic origin. Thirty-two formalin-fixed, paraffin-embedded cases were used to construct a tissue microarray. Immunohistochemistry for INSM1 and OTP was performed and scored semi-quantitatively. INSM1 was diffusely expressed in 60% of gynecologic tumors, 71.4% of mammary carcinoma, and 25% of prostate adenocarcinoma with NE differentiation. Diffuse expression of OTP was detected in 50% of prostate adenocarcinoma with NE differentiation and 100% neuroendocrine carcinoma of the ovary. Immunostain for achaete-scute homolog 1, chromogranin, synaptophysin, and CD56 supported the NE and/or neuroepithelial differentiation of the tumors. In summary, INSM1 is expressed in most of the tumors with NE and neuroepithelial differentiation in this study, confirming the diagnostic utility of INSM1 as a novel and sensitive marker of NE/neuroepithelial differentiation. The expression of OTP in some NE tumors outside of lung expands the spectrum of tumors that may express this biomarker and should be considered when working up a NE tumor of unknown primary site.

Metastatic breast cancer simulating well-differentiated neuroendocrine neoplasms of visceral organs

A series of metastatic breast carcinoma (MBC) mimicking visceral well-differentiated neuroendocrine neoplasms has not previously been reported. We identified 5 consultation cases originally submitted as neuroendocrine neoplasms in women but that were found to be MBC on subsequent review. All 5 neoplasms demonstrated nested architecture and relatively uniform nuclei. Four patients had a known history of breast cancer (remote in 3 and concurrent in 1), but the metastases (3 liver, 1 lung) labeled for chromogranin and/or synaptophysin, prompting misdiagnosis as neuroendocrine neoplasm. In a fifth case, a liver metastasis in a patient with a known pancreatic endocrine neoplasm was originally thought to be of pancreatic origin; an occult concurrent primary breast cancer (PBC) was subsequently identified as the source. On further immunohistochemistry (IHC), all metastases evaluated were diffusely, strongly positive for estrogen receptor (5/5 cases) and GATA3 (4/4 cases). Three patients had previously received ineffective treatment for neuroendocrine carcinoma. Based on the consultation diagnosis, all 4 patients with follow-up received hormone therapy, which was effective in 3. In a separate tissue microarray cohort of paired PBCs and hematogenous MBCs, chromogranin and/or synaptophysin IHC labeling was typically negative and increased from the PBC to the MBC in only 5% of cases. In conclusion, although neuroendocrine differentiation is uncommon in breast cancer and does not commonly increase in metastases, MBC with neuroendocrine differentiation should be considered in patients with visceral neuroendocrine neoplasms of unknown primary site. Diffuse IHC labeling for estrogen receptor and GATA3 helps establish the correct diagnosis.

Primary breast carcinomas with neuroendocrine features: Clinicopathological features and analysis of tumor growth patterns in 36 cases

Primary breast carcinoma with neuroendocrine features (NEBC) is an uncommon tumor. In the classification of WHO 2012, these tumors were categorized as: 1- neuroendocrine tumor, well-differentiated; 2- neuroendocrine carcinoma, poorly differentiated/small cell carcinoma; and 3- invasive breast carcinoma with neuroendocrine differentiation. In this study, we reviewed NEBC except poorly differentiated/small cell carcinoma variant in order to define the morphological growth patterns and cytonuclear details of these tumors. All breast surgical excision materials between 2007 and 2016 were re-evaluated in terms of neuroendocrine differentiation. Thirty-six cases showing positive staining for synaptophysin and/or chromogranin A in ≥50% of tumor cells were included in the study. All cases were female with a mean age of 67.4. Mean tumor diameter was 26 mm. Multifocality was noted in 5 cases. Grossly, they were mostly infiltrative mass lesions. T stages, identified in 34 cases, were as follows: 13 cases with pT1; 19 pT2 and 2 pT3. We described schematically 4 types of patterns depending on predominant growth pattern, except one case: 1) Large-sized solid cohesive groups (6 cases), 2) Small- to medium-sized solid cohesive groups with trabeculae/ribbons and glandular structures (6 cases), 3) Mixed growth patterns (20 cases), 4) Invasive tumor with prominent extracellular and/or intracellular mucin (3 cases). The tumor cells were mostly polygonal-oval with eosinophilic/eosinophilic-granular cytoplasm. The nuclei of tumor cells were mostly round to oval with evenly distributed chromatin. Only 5 cases showed high grade nuclear and histological features. Molecular subtypes of the cases were as follows: 33 luminal A, 2 luminal B, and 1 triple negative. NEBC should come to mind when a tumor display one of the morphological patterns described above, composed of monotonous cells with mild to moderate nuclear pleomorphism and abundant eosinophilic/eosinophilic granular or clear cytoplasm, especially in elderly patients.

Triple receptor-positive primary neuroendocrine carcinoma of breast in a young patient

Primary neuroendocrine carcinoma of breast is a very rare malignancy and preoperative diagnosis is difficult by clinical examination alone.Most oftenly, histopathological examination (HPE) and immunohistochemistry (IHC) studies are required to establish the diagnosis. We describe here a case of a primary neuroendocrine carcinoma of right breast in a 32-year-old woman. The patient underwent a right modified radical mastectomy, and the diagnosis was conclusively established postoperatively by the HPE and IHC reports. The IHC report revealed positive status of oestrogen, progesterone and Herceptin receptors.

Comprehensive clinical and molecular analyses of neuroendocrine carcinomas of the breast

Neuroendocrine breast carcinomas represent a rare subtype of breast cancer. Their definition, prevalence, and prognosis remain controversial in the literature. The 2012 WHO classification of breast cancer categorizes neuroendocrine carcinomas into three morphologically distinct subtypes: well-differentiated neuroendocrine tumors, poorly differentiated neuroendocrine carcinomas, and invasive breast carcinomas with neuroendocrine differentiation. We aimed to gain insight into the clinical, morphologic, phenotypic, and molecular features of 47 neuroendocrine breast carcinomas. Targeted next-generation sequencing by an AmpliSeq 22 cancer gene hotspot panel and the Prosigna assay were performed on 42/47 and 35/47 cases, respectively. Average age at diagnosis was 69 years. All tumors were estrogen receptor-positive and the large majority expressed progesterone receptor (89%), GATA3 (98%), FOXA1 (96%), and CK8/18 (98%). There was an almost equal distribution of luminal A (52%) and B (48%) carcinomas. Almost half of the cohort (49%) displayed a high risk of recurrence score with the Prosigna test. Patients with a neuroendocrine carcinoma had a shorter disease-free survival compared with those affected by carcinomas of no special type matched for age, size, grade, and estrogen receptor status. No significant differences were observed in terms of overall survival. Stratification of neuroendocrine carcinomas using the 2012 WHO criteria did not reveal statistically significant differences among the distinct categories (well-differentiated neuroendocrine tumors, poorly differentiated neuroendocrine carcinomas, and invasive breast carcinomas with neuroendocrine differentiation), in terms of either progression-free or overall survival. Our targeted sequencing analysis found three cases (7%) harboring a PIK3CA mutation, and in three other cases (7%) TP53 mutations were detected. This study showed that neuroendocrine breast carcinoma is a distinct subtype of luminal carcinoma with a low rate of PIK3CA mutations and with an aggressive clinical behavior. An accurate identification of neuroendocrine differentiation may be useful to better tailor patient adjuvant therapy within luminal carcinomas.

Neuroendocrine Tumors of the Breast

Primary neuroendocrine tumors of the breast are a rare and underrecognized subtype of mammary carcinoma. Neuroendocrine tumors of the breast occur predominately in postmenopausal women. The tumors are subclassified into well-differentiated and poorly differentiated neuroendocrine tumors, and invasive breast carcinoma with neuroendocrine features. Well-differentiated tumors show architectural similarity to carcinoids of other sites but lack characteristic neuroendocrine nuclei. Poorly differentiated neuroendocrine tumors are morphologically identical to small cell carcinoma of the lung. Neuroendocrine differentiation, seen in up to 30% of invasive breast carcinomas, is most commonly associated with mucinous and solid papillary carcinomas. The diagnosis of neuroendocrine differentiation requires expression of the neuroendocrine markers synaptophysin or chromogranin. The main differential diagnosis is a metastatic neuroendocrine tumor from an extramammary site. Neuroendocrine tumors of the breast are treated similarly to other invasive breast carcinomas. Although no consensus has been reached on the prognosis, most studies suggest a poor outcome.

High-grade poorly differentiated neuroendocrine carcinoma of the breast with low oncotype Dx recurrence score: A case report

Primary neuroendocrine carcinoma of the breast (NECB) is a rare malignant tumor with controversial biological behavior and a lack of data guiding treatment decisions due to its scarcity. Cancer gene-expression profiling tests provide a better indication of clinical prognosis and help determine the best clinical management versus the traditional clinical and pathological parameters. This is a report of a NECB with a genetic assay that showed a low-risk tumor despite high-grade and poorly differentiated histopathological features. Patient outcomes correlate with the low risk classification without the need for adjuvant chemotherapy despite the standard clinical-pathologic approach. Analysis of cancer related genes expression and outcomes in historical NECB may elucidate new insight of this rare disease.

Merkel cell carcinoma, melanoma, metastatic mimics of breast cancer

Merkel cell carcinoma and melanoma can each occur primarily in breast skin, or metastasize to the breast. The breast is a rare site of metastasis of essentially any and every type of tumor, including carcinomas, sarcomas, and hematolymphoid neoplasms, and 10-30% of breast metastases may represent the initial presentation of disease. Although metastases generally recapitulate histologic features of the primary tumor, they are diagnostically challenging given their rarity and morphologic overlap with breast carcinoma, including special types of breast cancer. Histologic clues may include lack of carcinoma in situ, lack of central elastosis, pattern of infiltration around normal breast structures, yet none of these are specific. Careful correlation with clinical history and judicious use of immunostain panels is essential in approaching these cases.

Neuroendocrine Tumors of the Breast

A small but increasingly recognized and studied subset of breast carcinomas are characterized by neuroendocrine (NE) differentiation. As with nearly all forms of breast neoplasia, NE tumors are characterized by considerable heterogeneity in microscopic appearance and clinical aggressiveness. About half of NE breast carcinomas recapitulate the histological spectrum typical of their counterparts in other organ systems, varying from "carcinoid-like" to small cell carcinoma, with most representing intermediate grade tumors. Despite NE morphology, these tumors have a high frequency of estrogen receptor expression. Clinical outcomes of women with NE breast carcinomas are reliably grade and stage dependent. Tumors associated with "solid papillary" differentiation comprise the remaining cases of NE breast neoplasia. Solid papillary carcinoma is an intrinsically low grade/favorable prognosis class of breast neoplasia that usually presents in post-menopausal age groups. About half of solid papillary carcinoma present as a distinctive pattern of ductal carcinoma in situ that may be difficult to recognize owing to its close resemblance to florid proliferative lesions. Invasive solid papillary carcinomas are characterized by a variety of histological patterns and often show mucinous differentiation. Future studies are necessary to better define the histogenesis, optimal classification, and improved directed therapies for NE breast neoplasia.

Primary neuroendocrine breast carcinomas: a retrospective analysis and review of literature

Background

Primary neuroendocrine breast carcinomas (NEBCs) are a rare type of breast carcinomas that lack comprehensive recognition, including the clinicopathological features, therapeutic strategies, and prognostic significance. The aim of this retrospective analysis is to present and analyze our own data of primary NEBCs.

Materials and methods

We retrospectively reviewed the medical records from 2005 to 2015 in The First Affiliated Hospital of Chongqing Medical University, Chongqing, People’s Republic of China to obtain a cohort of breast carcinoma patients who were confirmed to have primary NEBC by histopathology. The detailed clinical data along with histopathology, treatment, and follow-up aspects were gathered for analysis.

Results

This retrospective analysis included 19 patients with a histopathological diagnosis of primary NEBC from 2005 to 2015. Their mean age was 59.2 years (ranging from 17 to 82 years). The majority of patients (15/19) focused on stages I and II. Of the 15 patients, 14 were positive for estrogen receptor, and 11 were positive for progesterone receptor. For neuroendocrine markers, the expression rates were 8/19, 14/18, 12/14, and 2/6 for chromogranin A, synaptophysin, neuron-specific enolase, and CD56, respectively. All operable patients except the one stage M1 underwent a surgery and 4/18 had axillary lymph node metastasis. Chemotherapy was performed in 12/19, and endocrine therapy in 8/10. With a median follow-up of 59.2 months, only 2 cases progressed after postoperative systemic therapy.

Conclusion

The understanding of NEBC is limited due to its rarity. More evidence should be provided to enhance the understanding of NEBC, especially for diagnosis, treatment, and prognosis.

A case of multicentric low-grade neuroendocrine breast tumor with an unusual histological pattern

Neuroendocrine features are detectable in carcinomas of the breast either as scattered cells, that are recognized by their expression of neuroendocrine cell markers. Instead, pure breast carcinomas with neuroendocrine features (NEBC) are very rare and represent <1% of all breast cancer. Usually NEBC may be well or poorly differentiated and more frequent in older woman. These tumors showed variable histological pattern but a common feature is represented by expression of neuroendocrine markers. Here we report a case of a primary multicentric low-grade neuroendocrine carcinoma of the breast presented because of its rarity and for the unusual tubular and cribriform pattern resembling a well-differentiated conventional breast carcinoma. The tumor was treated with left quadrantectomy with concomitant wide excisional biopsy of other two nodules and lymph node sentinel biopsy. No recurrence was observed during 1-year follow-up. Because of its rarity and variability of morphologic features, there exist diagnostic challenges for pathologists to differentiate primary NEBC to some conventional breast carcinomas and to the breast metastasis from neuroendocrine tumor of the lung or gastrointestinal tract. It is important to be able recognize this tumor in order to avoid potential misdiagnosis and improper management of afflicted patients.

Mucinous carcinoma of the breast: a comparative study on cytohistological findings associated with neuroendocrine differentiation

OBJECTIVE

Mucinous carcinoma (MCA) may show neuroendocrine differentiation (ND), but the cytological features characteristic of ND remains elusive. We compared fine needle aspiration (FNA) findings of MCA between cases with high and low degrees of ND.

METHODS

Histological sections of 37 MCA cases were immunohistochemically evaluated for expression of chromogranin A and synaptophysin, and were graded as 0 to 3+ degrees of ND. They were divided into low ND (grade 0 and 1+) and high ND (grade 2+ and 3+) groups. Pre-operative FNA samples of each group were assessed for cytological features.

RESULTS

The mean age of the high ND group (n = 18) was higher than the low ND group (n = 19, P = 0.01). In FNA samples of the high ND group, 17 cases showed moderate to severe degrees of discohesiveness, but low ND cases mainly showed no or only mild discohesiveness (P < 0.001). Nine of the low ND cases displayed overlapped, cohesive cell clusters, whereas, in the high ND cases, the cells were arranged in a loose, flat and monolayered pattern (P = 0.045). Fourteen of the high ND cases had round nuclei, but oval nuclei were predominant in the low ND cases (P = 0.027). The nuclei were eccentrically located in 12 of the high ND cases but were centrally located in 14 of the low ND cases (P = 0.01).

CONCLUSIONS

Mucinous carcinoma with high ND may be diagnosed by the presence of discohesiveness, a flat, monolayered pattern, and round or eccentrically located nuclei. Features of ND in carcinomas in other organs, such as intracytoplasmic granules and coarse chromatin, may not be reliable cytological features of ND in MCA.

Novel mutations in neuroendocrine carcinoma of the breast: possible therapeutic targets

Primary neuroendocrine carcinoma of the breast is a rare variant, accounting for only 2% to 5% of diagnosed breast cancers, and may have relatively aggressive behavior. Mutational profiling of invasive ductal breast cancers has yielded potential targets for directed cancer therapy, yet most studies have not included neuroendocrine carcinomas. In a tissue microarray screen, we found a 2.4% prevalence (9/372) of neuroendocrine breast carcinoma, including several with lobular morphology. We then screened primary or metastatic neuroendocrine breast carcinomas (excluding papillary and mucinous) for mutations in common cancer genes using polymerase chain reaction-mass spectroscopy (643 hotspot mutations across 53 genes), or semiconductor-based next-generation sequencing analysis (37 genes). Mutations were identified in 5 of 15 tumors, including 3 with PIK3CA exon 9 E542K mutations, 2 of which also harbored point mutations in FGFR family members (FGFR1 P126S, FGFR4 V550M). Single mutations were found in each of KDR (A1065T) and HRAS (G12A). PIK3CA mutations are common in other types of breast carcinoma. However, FGFR and RAS family mutations are exceedingly rare in the breast cancer literature. Likewise, activating mutations in the receptor tyrosine kinase KDR (VEGFR2) have been reported in angiosarcomas and non-small cell lung cancers; the KDR A1065T mutation is reported to be sensitive to VEGFR kinase inhibitors, and fibroblast growth factor receptor inhibitors are in trials. Our findings demonstrate the utility of broad-based genotyping in the study of rare tumors such as neuroendocrine breast cancer.

Neuroendocrine differentiation in breast carcinoma: clinicopathological features and outcome

AIMS

Primary neuroendocrine (NE) breast carcinoma (BC) is an entity with a wide range of prevalence and poorly defined clinical behaviour. We evaluated the prevalence, clinicopathological features and clinical outcome of NEBC.

METHODS AND RESULTS

Immunohistochemical staining for synaptophysin and chromogranin A was performed on whole sections from 1232 consecutive cases of invasive BC. We divided NEBC into focal (10-49% positive cells) and diffuse (≥50% positive cells) and compared the outcome of patients with NEBC with strictly matched non-NEBC. A total of 128 BC showed NE differentiation (10.4%): 84 diffuse (6.8%) and 44 focal (3.6%). NE differentiation showed a significant association with T4 stage (P = 0.001), solid-papillary and mucinous histotype (P < 0.0001), G2 grading (P = 0.002), positive oestrogen receptor (ER) (P = 0.003) and progesterone receptor (PR) (P = 0.002). Almost 90% of NEBC were ER(+) /HER2(-) and more than half ER(+) /HER2(-) /Ki67≥14%. Kaplan-Meier analysis revealed that patients with NEBC showed worse disease-free survival (DFS) (P = 0.04) compared to matched non-NEBC. We did not find significant differences regarding clinicopathological features, DFS and CSS between diffuse and focal neuroendocrine BC.

CONCLUSIONS

This study demonstrates that NEBC represents 7-10% of invasive BC and that NE differentiation does not affect the prognosis of BC in terms of CSS.

Impact of histological subtype on long-term outcomes of neuroendocrine carcinoma of the breast

Although rare, neuroendocrine carcinoma of the breast (NECB) is becoming an increasingly recognized entity. The current literature is limited to case reports and small series and therefore a comprehensive population-based analysis was conducted to investigate the clinicopathologic features and long-term outcomes associated with NECB. We included all patients in the SEER Database from 2003 to 2010 with a diagnosis of NECB. The 2012 WHO classification system was used to categorize patients based on histopathologic diagnosis: well-differentiated neuroendocrine tumors, small/oat cell or poorly differentiated neuroendocrine tumors, adenocarcinoma with neuroendocrine features (ANF), large cell neuroendocrine and carcinoid tumors. Survival analysis was performed for disease specific (DSS) and overall (OS) survival. Of the 284 cases identified, 52.1% were classified as well-differentiated, 25.7% small cell, 14.8% ANF, 4.9% large cell, and 2.5% carcinoid. In general, patients presented with advanced disease: 36.2% had positive lymph node metastases and 20.4% presented with systemic metastases. Five-year DSS rates for stage I-IV NECB were 88.1, 67.8, 60.5, and 12.4%, respectively, while five-year OS rates were 77.9, 57.3, 52.9, and 8.9%, respectively. DSS and OS were significantly different for well-differentiated neuroendocrine tumors and ANFs compared to small cell and carcinoid tumors. On univariate Cox proportional hazards regression, small cell carcinoma was significantly associated with worse DSS (OR 1.97, 95% CI 1.05-3.67) and OS (OR 2.66, 95% CI 1.49-4.72) compared to other neuroendocrine tumors. NECB is associated with advanced stage disease at presentation and an unfavorable prognosis for stage II-IV disease and small cell, large cell, and carcinoid histologic subtypes.

Primary neuroendocrine carcinoma of the breast: clinical, imaging, and histologic features

OBJECTIVE

The purpose of this study was to evaluate the clinical, imaging, and histopathologic findings of primary neuroendocrine carcinoma of the breast.

MATERIALS AND METHODS

A pathology database was searched for the records of patients with a histopathologic diagnosis of primary neuroendocrine carcinoma of the breast who had undergone mammography, sonography, or MRI between 1984 and 2011. The imaging studies of eligible patients were retrospectively reviewed according to the BI-RADS lexicon, and clinical presentation and histopathologic characteristics were documented. Imaging characteristics were compared with historical controls of invasive mammary carcinoma.

RESULTS

Eighty-seven patients (84 women, three men; mean age, 62.9 years; range, 28-89 years) were included in the study. The mean tumor size was 3.1 cm (range, 0.6-11 cm). Sixty-five of 84 (77.4%) cancers were estrogen and progesterone receptor positive and ERBB2 negative. A palpable mass (55.8%) was a common clinical manifestation. A high-density, round or oval, or lobular mass with nonspiculated margins on mammograms and an irregular (65.4%), hypoechoic (78.4%) mass, with indistinct margins (43.5%), no or enhanced posterior acoustic features (77.9%) on sonograms were common findings. MRI revealed an irregular mass (83.3%), irregular margins (63.6%), and washout kinetics (85.7%). Neuroendocrine carcinoma presented more frequently as masses on mammograms. Calcifications were infrequent compared with their occurrence in invasive mammary cancer.

CONCLUSION

Primary neuroendocrine carcinoma of the breast has mammographic features that differ from those of invasive mammary carcinoma. A round, oval, or lobular mass with nonspiculated margins, positive estrogen and progesterone receptor results, and negative ERBB2 results should raise suspicion of primary neuroendocrine carcinoma.

Peptide Receptor Radionuclide Therapy (PRRT) in a Patient Affected by Metastatic Breast Cancer with Neuroendocrine Differentiation

BACKGROUND

Breast cancer (BC) is the most frequent cancer in European women with nearly 30% of the patients eventually developing metastases. Neuroendocrine differentiation is a rare event, but overexpression of somatostatin receptors in BC has been reported in many studies.

CASE REPORT

A patient with liver metastases from BC was treated with peptide receptor radionuclide therapy (PRRT). Computed tomography scan and biochemical examinations showed a clear response to radionuclide therapy.

CONCLUSION

PRRT may be useful in metastatic BC patients.

Neuroendocrine differentiation correlates with hormone receptor expression and decreased survival in patients with invasive breast carcinoma

AIMS

Invasive breast carcinoma (IBC) with neuroendocrine (NE) differentiation has been controversial in terms of its definition and clinical outcome. We investigated the incidence and clinical significance of NE differentiation in patients with IBC.

METHODS AND RESULTS

We performed immunohistochemistry for NE markers, chromogranin-A and synaptophysin on 1428 IBC samples using tissue microarrays and classified cases with NE differentiation into two groups, focal (1-49% tumour cells positive for any NE marker) and diffuse (≥50% tumour cells positive) groups. Fifty-nine cases (4.1%) showed NE differentiation immunohistochemically, and the majority did not show typical NE morphology. The presence of NE differentiation showed a significant association with positive oestrogen receptor (P = 0.001) and progesterone receptor (P = 0.008) status. Patients with NE differentiation showed worse overall survival (OS) and disease-free survival (DFS) than those without NE differentiation in both univariate (P < 0.001 for both) and multivariate (OS, P = 0.004; DFS, P < 0.001) analyses.

CONCLUSIONS

IBC with NE differentiation is a distinct subtype of mammary carcinoma with an aggressive clinical outcome.

Locally-advanced primary neuroendocrine carcinoma of the breast: case report and review of the literature

Background

Primary neuroendocrine carcinoma of the breast is a heterogeneous group of rare tumors with positive immunoreactivity to neuroendocrine markers in at least 50% of cells. Diagnosis also requires that other primary sites be ruled out and that the same tumor show histological evidence of a breast in situ component. Primary neuroendocrine carcinoma of the breast rarely presents as locally advanced disease and less frequently with such widespread metastatic disease as described herein. The review accompanying this case report is the first to provide an overview of all the cases of primary neuroendocrine carcinoma of the breast published in the literature and encompasses detailed information regarding epidemiology, histogenesis, clinical and histologic diagnosis criteria, classification, surgical and adjuvant treatment, as well as prognosis. We also provide recommendations for common clinical and histologic pitfalls associated with this tumor.

Case presentation

We describe a case of a 51-year-old Hispanic woman initially diagnosed with locally-advanced invasive ductal carcinoma that did not respond to neodjuvant treatment. After undergoing modified radical mastectomy the final surgical pathology showed evidence of alveolar-type primary neuroendocrine carcinoma of the breast. The patient was treated with cisplatin/etoposide followed by paclitaxel/carboplatinum. Thirteen months after surgery the patient is alive, but developed pulmonary, bone, and hepatic metastasis.

Conclusion

The breast in situ component of primary neuroendocrine carcinoma of the breast may prevail on a core biopsy samples increasing the probability of underdiagnosing this tumor preoperatively. Being aware of the existence of this disease allows for timely diagnosis and management. Optimal treatment requires simultaneous consideration of both the neuroendocrine and breast in situ tumor features.