Secretory breast carcinoma: a clinicopathological and immunophenotypic study of 15 cases with a review of the literature

Nuclear staining for pan-Trk by immunohistochemistry is highly specific for secretory carcinoma of breast: pan-Trk in various subtypes of breast carcinoma

AIMS

Secretory carcinoma of breast (SCB) typically harbours ETV6-NTRK3 gene fusion. Pan-Trk immunohistochemistry analysis (IHC) has been shown to be sensitive for SCB diagnosis. However, weak focal pan-Trk nuclear staining was previously found in 10% of non-secretory breast carcinomas. To further examine pan-Trk IHC specificity, we evaluated pan-Trk staining in various breast carcinoma subtypes.

METHODS

The study cohort consisted of 346 invasive breast carcinomas (IBCs), including 8 SCBs and 48 triple-negative histological mimickers (36 metaplastic carcinomas, including 12 matrix-producing carcinomas; 5 adenoid cystic carcinomas; 5 apocrine carcinomas; 2 acinic cell carcinomas), 101 triple-negative IBCs of no special type, 101 estrogen receptor (ER)-positive/HER2-negative IBCs and 88 HER2-positive IBCs. Six salivary gland secretory carcinomas were also included. Pan-Trk IHC was performed on tumours using a rabbit monoclonal pan-Trk antibody. Any nuclear staining in the invasive carcinoma cells was considered positive.

RESULTS

All 14 secretory carcinomas from breast and salivary gland exhibited moderate to strong pan-Trk nuclear staining. In contrast, no pan-Trk nuclear staining was identified in any of the 338 non-secretory IBCs. Focal cytoplasmic pan-Trk staining was observed in nine non-secretory IBCs (2.7%), and was considered nonspecific and negative.

CONCLUSIONS

Our results indicate that pan-Trk nuclear staining is highly specific for SCB. In low-grade to intermediate-grade IBCs that share histological features with SCB, adding pan-Trk to a routing panel of estrogen receptor/progesterone receptor/HER2 is highly diagnostic. Our results also support using pan-Trk IHC to differentiate SCB from its triple-negative histological mimickers, such as adenoid cystic carcinoma, matrix-producing carcinoma, apocrine carcinoma and acinic cell carcinoma.

Case report: Diagnostic trap: a extremely rare metastatic myoepithelial carcinoma of breast

Background

Myoepithelial carcinoma (MECA) is a malignant tumor primarily affecting the salivary gland, most frequently in the parotid gland. It can manifest as primary or secondary to pleomorphic adenoma or benign myoepithelioma. MECA exhibits aggressive behaviors. In particular, primary MECA is more aggressive, frequently recurring or metastasizing distantly. Its morphological and immunohistochemical characteristics overlap with various tumors, posing challenges in its recognization as a distinct entity. Consequently, MECA may be frequently misdiagnosed, mainly when occurred in the mammary gland. This chance for misdiagnosis poses significant challenges in clinical diagnosis and treatment.

Case demonstration

A 77-year-old woman with a history of pleomorphic adenoma presented with a palpable lump in the right breast for 3 months. Subsequent core needle biopsy (CNB) and modified radical mastectomy were performed, with samples subjected to histopathological examination. Based on the patient's history, histomorphologic features, immunohistochemistry (IHC) results and results of FISH, the pathological diagnosis confirmed MECA in the mammary gland. Postoperative chemotherapy was administered, and the patient exhibited a favorable prognosis during a 40-month follow-up period.

Conclusions

Primary MECA in the mammary gland is exceedingly rare, metastasis from the salivary gland MECA to the mammary gland is even rarer and has not been previously reported. This study presents the first documented case of MECA originating from the parotid gland metastasizing to the mammary gland (also known as breast). Highlighting this case aims to raise awareness among clinical pathologists to prevent underdiagnosis and misdiagnosis of this tumor entity.

Salivary gland-like tumors of the breast: Histopathologic and genetic features with clinical implications

Salivary gland-like tumors of the breast are rare neoplasms that share morphologic, immunophenotypic, and/or genetic features with their salivary gland counterparts, highlighting a shared underlying histopathogenesis in most cases. Salivary gland-like carcinomas included in the World Health Organization classification of breast tumors are adenoid cystic carcinoma, secretory carcinoma, mucoepidermoid carcinoma, acinic cell carcinoma, and the exceedingly rare polymorphous adenocarcinoma. These carcinomas are usually triple negative for estrogen receptor and progesterone receptor expression and HER2 overexpression, yet generally have favorable prognosis, in contrast to high-grade triple negative carcinomas of no special type. On the other hand, a small subset, such as solid-basaloid adenoid cystic carcinoma, rare high-grade carcinomas, and those associated with transformation to other types of high-grade invasive carcinoma can behave more aggressively. Other salivary gland-like tumors of the breast, such as pleomorphic adenoma and adenomyoepithelioma, are usually benign but can rarely undergo malignant transformation. Although clinical experience with salivary gland-like breast tumors is overall limited, their recognition and accurate classification has important implications for prognosis and clinical management, especially to avoid overtreatment of salivary gland-like carcinomas. The identification of characteristic genetic alterations and/or immunohistochemical surrogates in many of these tumors has practical applications to establishing an accurate diagnosis and directing clinical management. This review highlights the histopathologic and genetic characteristics of salivary gland-like breast tumors and the implications of the diagnosis for current clinical management.

Secretory Carcinoma of the Breast: Radiologic-Pathologic Correlation

Secretory carcinoma is a rare, low-grade, special histological type of invasive breast carcinoma. Although it is the most common primary breast cancer in the pediatric population, most cases are diagnosed in adults, with a median age of 48 years (range 3 to 91 years). It most often presents as a painless and slowly growing palpable lump. Imaging findings are nonspecific. Secretory carcinomas have abundant periodic acid-Schiff positive intracytoplasmic and extracellular secretions on histopathology. Nearly all secretory carcinomas have mild to moderate nuclear pleomorphism with low mitotic activity. Over 80% (86/102) of secretory carcinomas display the translocation of t(12;15)(p13;q25), resulting in ETV6::NTRK3 gene fusion. Secretory carcinoma generally has an indolent course and has a better prognosis and overall survival than invasive breast carcinoma of no special type. A good prognosis is associated with age <20 years, tumor size <2 cm, and ≤3 axillary lymph node metastases. Metastases beyond the ipsilateral axillary lymph nodes are rare, with the most common sites involving the lung and liver. Except for the potential addition of targeted drug therapy for NTRK fusion-positive tumors, the treatment approach is otherwise similar to invasive breast carcinomas of similar receptor status.

Special Types of Breast Cancer: Clinical Behavior and Radiological Appearance

Breast cancer is a complex disease that includes entities with different characteristics, behaviors, and responses to treatment. Breast cancers are categorized into subgroups based on histological type and grade, and these subgroups affect clinical presentation and oncological outcomes. The subgroup of "special types" encompasses all those breast cancers with insufficient features to belong to the subgroup "invasive ductal carcinoma not otherwise specified". These cancers account for around 25% of all cases, some of them having a relatively good prognosis despite high histological grade. The purpose of this paper is to review and illustrate the radiological appearance of each special type, highlighting insights and pitfalls to guide breast radiologists in their routine work.

Secretory Carcinoma of the Breast with Apocrine Differentiation-A Peculiar Entity

Background and Objectives: Secretory carcinoma of the breast is an uncommon histological subtype of breast cancer. There is little research on this entity and only a few larger studies, which lack consensus. We aim to report a particular apocrine differentiation in this subtype and ponder upon the clinical outcome of this case. Case presentation: We report the case of a 72-year-old female patient who presented to our hospital with a suspicious breast tumor. Core biopsy and mastectomy showed a low-grade breast carcinoma, a secretory subtype with apocrine differentiation. Immunohistochemistry confirmed both the secretory nature and the apocrine nature of the tumor cells. Surgical excision was considered curative and the patient is under long-term surveillance for any recurrences. Conclusions: There is very little research on the clinical behavior of secretory carcinomas with apocrine differentiation. The clinical outcome is unknown and, unfortunately, besides surgery, no other adjuvant treatments have shown efficacy. Further studies on long-term clinical progression are required for this rare entity.

A Comparative Evaluation of TRPS1 and GATA3 in adenoid cystic, secretory, and acinic cell carcinomas of the breast and salivary gland

GATA3 is the most used marker to determine tumors' breast origin, but its diagnostic value in triple-negative breast cancer (TNBC) is limited. The newly identified TRPS1 is highly sensitive and specific for breast carcinoma, especially TNBC. Here, we compared the utility of TRPS1 and GATA3 expression in a subset of salivary gland-type breast tumors (including adenoid cystic, acinic cell, and secretory carcinomas [AdCC, ACC, and SC, respectively]), and we compared TRPS1 and GATA3 expression of such tumors with head and neck (H&N) and AdCC of upper respiratory tumors. TRPS1 was strongly expressed in basaloid TNBC and AdCCs with solid components, including 100 % of mixed and solid breast AdCCs. However, TRPS1 was positive in only 50 % cribriform AdCCs. Expression patterns of TRPS1 in H&N and upper respiratory AdCC were similar. TRPS1 was positive in 30 % of H&N cribriform AdCCs but was strongly expressed in mixed AdCC (67 %) and solid AdCC (100 %). In the upper respiratory AdCCs, TRPS1 was positive in 58.4 % of cribriform AdCCs and positive in 100 % of AdCCs with solid components. On the contrary, GATA3 was negative in predominant AdCCs of the breast, H&N, and upper respiratory tract. These data show that GATA3 and TRPS1 expression varies AdCCs. In addition, TRPS1 and GATA3 expression patterns were similar SC and ACC of breast and H&N. Both markers were positive in SC and negative in ACC. Therefore, TRPS1 and GATA3 cannot be used to differentiate salivary gland-type carcinomas of breast origin from those of upper respiratory or H&N origin.

Secretory Carcinoma of Breast: A Population-Based Study

AIM

In this study, it was aimed to evaluate the characteristic features and survival of secretory carcinoma of the breast (SCB), which is one of the rare malignant tumors of the breast.

METHODS

Data of patients with histopathological diagnosis of SCB between 2010 and 2019 were extracted from the SEER database. These patients were evaluated in terms of age, race, molecular subtype, grade, estrogen receptor (ER), progesterone receptor (PR), HER2 receptor, TNM stage, surgical status, chemotherapy and radiotherapy treatment. Overall survival (OS) and breast cancer-specific survival (BCSS) of the whole population and subgroups [in terms of surgery procedure (mastectomy/breast-conserving surgery), and hormone receptor status (positive/negative)] were analyzed.

RESULTS

70 patients were included in the study. The mean age was 57 years (range 2-82). 32.9% of the patients were diagnosed under the age of 50. 97.1% of the patients were female; 2.9% were male. The vast majority of patients were white race (81.4%). Although the rates of localization were higher in the upper outer quadrant (31.4%), centrally located tumors (18.5%) were also quite common. The most frequently detected molecular subtype was hormone positive/HER2 negative. All patients were non-metastatic, 81.4% of patients did not have lymph node metastases, and most of the patients were stage IA. Median follow-up was 37 months (range 0-118 months). Considering all patients, OS was 76.3%, 5-year OS was 91.8%, and BCSS was 88%, 5-year BCSS was 97.8%. There was no statistically significant difference in OS and BCSS according to subgroups (P > .01).

CONCLUSION

SCB, a rare histopathologic type, has high OS and BCSS rates.

Secretory breast carcinoma: clinicopathological features and prognosis of 52 patients

PURPOSE

Secretory breast carcinoma is a rare histological subtype of invasive breast cancer and considered with an indolent clinical behavior. This study was conducted to analyze the clinicopathological features of patients with secretory breast carcinoma (SBC), explore the outcome, and compare the prognostic difference with invasive ductal breast carcinoma (IDC). METHODS AND MATERIALS: Patients with SBC diagnosed between 2006 and 2017 from Fudan University Shanghai Cancer Center were included in the study, excluding patients with previous malignant tumor history and incomplete clinical data or follow-up records. Peculiar clinicopathological and immunohistochemical features of the cases were fully described. Clinical data of 4979 cases of IDC were also evaluated during this period. After propensity score matching, prognostic analysis of SBCs and IDCs was calculated by Kaplan-Meier method and landmark analysis method.

RESULTS

The data of 52 patients diagnosed with SBC were identified from the pathological files. Among them, 47 patients were women, and 5 were men. The median age of the 52 SBCs was 46 years (mean, 48.1 years; range, 10-80 years). The tumor sizes ranged from 0.3 to 6.8 cm, with a mean of 3.5 cm. Eight patients (15.4%) had positive axillary lymph node involvement. The molecular classification was mostly triple-negative breast cancer (65.4%). Fluorescence in situ hybridization confirmed the presence of ETV6::NTRK3 rearrangement in 16 of 18 cases (88.9%). Furthermore, Kaplan-Meier survival analysis and landmark analysis demonstrated that there were no statistically significant differences in DFS and OS between SBC and IDC patients.

CONCLUSION

Although SBCs are generally associated with a favorable prognosis, our work exhibited that the clinicopathological features of SBC were partly different from former understandings, indicating that therapeutic procedure should be prudent. Further studies are necessary to fully identify the clinical behavior and predictive markers to improve diagnosis and management in this unique subtype of breast cancer.

Multimodal ultrasonic manifestations of secretory carcinoma of the breast

 Secretory carcinoma of the breast (SCB) is a rare and specific type of breast cancer. Owing to its rarity, the number of SCB reports available is limited, with most of them focusing on clinical and pathological characteristics but no reports on its multimodal ultrasound (US) features. Thus, we present a rare case of SCB, retrospectively analyzing manifestations of US and contrast-enhanced US, as well as its pathological basis, aiming to enhance the understanding of US image features of SCB and provide more valuable information for clinical diagnosis. Moreover, the treatment strategy adopted for this patient may serve as a template for future management of SCB.

[Rare tumours of the breast]

Breast tumours are the most common tumours in women but represent a very heterogeneous group. On the one hand, there are ductal and lobular carcinomas of the breast, representing 90% of tumours, whose clinicopathologic characteristics are well known. On the other hand, there are rare breast tumours, each of which represents less than 1% that limits their study through large cohorts. The objective of this work was to collect, update and synthesize knowledge on these rare tumours. A literature review was performed on the Medline and Google Scholar databases. We present here a selection of several rare tumours, providing updated data at the epidemiological, histopathological, genetic, clinical and radiographic, prognostic and therapeutic levels, taking into account the place of radiotherapy. Each tumour histology is unique and has its own characteristics, the management must therefore be adapted as much as possible and decided in a multidisciplinary meeting.

The Role of Novel Immunohistochemical Markers for Special Types of Breast Carcinoma

Some histologic special types of breast carcinoma harbor specific recurrent genetic alterations that are not seen in other types of breast carcinoma (no special type), namely adenoid cystic carcinoma, secretory carcinoma, and tall cell carcinoma with reversed polarity. These tumors have unique morphologic features, are triple-negative, that is, do not express hormone receptors or HER2, and are generally associated with a favorable prognosis. Adenoid cystic carcinoma, like its counterpart in other organs, shows a MYB-NFIB fusion gene that is the result of a recurrent t(6;9)(q22-23;p23-24) translocation. Other MYB alterations have been described that result in overexpression of MYB . Secretory carcinoma is characterized by an ETV6-NTRK3 gene fusion that is the result of recurrent (12;15);(p13;q25) translocation, which is also seen in mammary analog secretory carcinoma of the salivary gland. Tall cell carcinoma with reversed polarity shows IDH2 p.Arg172 hotspot mutations. Immunohistochemical antibodies have emerged that identify the underlying genetic alterations in these tumors and serve as useful diagnostic tools. This review will provide an update on the molecular features and diagnostic immunohistochemical markers that have become increasingly popular to aid in diagnosing these uncommon triple-negative breast tumors.

Secretory Breast Carcinoma: Report of Two Cases and Literature Review

Secretory Breast Carcinoma (SBC) is a rare subtype of breast cancer, predominantly affecting young women, and characterized by hormone receptor-negative and HER2-negative tumors with distinctive histological features, including secretory droplets within tumor cells. This article presents 2 unique cases of SBC, Case 1 involving a 42-year-old woman with triple-negative mammary carcinoma later diagnosed with triple-negative secretory carcinoma, and Case 2 featuring a 48-year-old woman with poorly differentiated adenocarcinoma subsequently identified as invasive mammary carcinoma of secretory type. Both cases received diverse treatment regimens, incorporating surgery, chemotherapy, radiotherapy, and hormone therapy. The importance of accurate diagnosis and the need for further research to optimize the management of this rare breast cancer subtype are emphasized. Raising awareness of SBC and reporting additional cases can enhance understanding and improve patient outcomes. Additionally, the integration of clinical, radiological, and histopathological findings, alongside specific molecular markers like S-100 and mammaglobin, is crucial for accurate SBC diagnosis. Given the lack of established guidelines for SBC management, collecting additional cases can aid in defining a more effective strategy for diagnosis, monitoring, and treatment, ultimately contributing to advancements in the field. Herein, we report 2 cases of this rare disease that were diagnosed and treated in our institution.

Rare subtypes of triple negative breast cancer: Current understanding and future directions

Rare subtypes of triple-negative breast cancers (TNBC) are a heterogenous group of tumors, comprising 5-10% of all TNBCs. Despite accounting for an absolute number of cases in aggregate approaching that of other less common, but well studied solid tumors, rare subtypes of triple-negative disease remain understudied. Low prevalence, diagnostic challenges and overlapping diagnoses have hindered consistent categorization of these breast cancers. Here we review epidemiology, histology and clinical and molecular characteristics of metaplastic, triple-negative lobular, apocrine, adenoid cystic, secretory and high-grade neuroendocrine TNBCs. Medullary pattern invasive ductal carcinoma no special type, which until recently was a considered a distinct subtype, is also discussed. With this background, we review how applying biological principals often applied to study TNBC no special type could improve our understanding of rare TNBCs. These could include the utilization of targeted molecular approaches or disease agnostic tools such as tumor mutational burden or germline mutation-directed treatments. Burgeoning data also suggest that pathologic response to neoadjuvant therapy and circulating tumor DNA have value in understanding rare subtypes of TNBC. Finally, we discuss a framework for advancing disease-specific knowledge in this space. While the conduct of randomized trials in rare TNBC subtypes has been challenging, re-envisioning trial design and technologic tools may offer new opportunities. These include embedding rare TNBC subtypes in umbrella studies of rare tumors, retrospective review of contemporary trials, prospective identification of patients with rare TNBC subtypes entering on clinical trials and querying big data for outcomes of patients with rare breast tumors.

TRK inhibitor in a patient with metastatic triple-negative breast cancer and NTRK fusions identified via cell-free DNA analysis

Tissue-agnostic indications for targeted therapies have expanded options for patients with advanced solid tumors. The Food and Drug Administration approvals of the programmed death-ligand 1 inhibitor pembrolizumab and the TRK inhibitors larotrectinib and entrectinib provide rationale for next-generation sequencing (NGS) in effectively all advanced solid tumor patients given potential for clinical responses even in otherwise refractory disease. As proof of concept, this case report describes a 64-year-old woman with triple-negative breast cancer refractory to multiple lines of therapy, found to have a rare mutation on NGS which led to targeted therapy with meaningful response. She initially presented with metastatic recurrence 5 years after treatment for a localized breast cancer, with rapid progression through four lines of therapy in the metastatic setting, including immunotherapy, antibody-drug conjugate-based therapy, and chemotherapy. Germline genetic testing was normal. Ultimately, NGS evaluation of cell-free DNA via an 83-gene assay (Guardant Health, Inc.) identified two NTRK3 fusions: an ETV6-NTRK3 fusion associated with the rare secretory breast carcinoma, and CRTC3-NTRK3, a novel fusion partner not previously described in breast cancer. Liver biopsy was sent for whole exome sequencing and RNA-seq analysis of tissue (BostonGene, Inc., Boston, MA, USA), which provided orthogonal confirmation of both the ETV6-NTRK3 and CRTC3-NTRK3 fusions. She was started on the TRK inhibitor larotrectinib with a marked clinical and radiographic response after only 2 months of therapy. The patient granted verbal consent to share her clinical story, images, and data in this case report. This case demonstrates the significant potential benefits of NGS testing in advanced cancer and the lessons we may learn from individual patient experiences.

Clinicopathological features and genomic profiles of a group of secretory breast carcinomas in which progressive cases have more complex genomic features

BACKGROUND

Secretory breast carcinoma (SBC) is a rare malignant breast neoplasm with distinct histological features, including solid, microcystic, tubular, and rarely papillary structures, traditionally characterized by a t (12;15) (p13:q25) translocation, which usually leads to ETV6-NTRK3 fusion, suggesting an early event in tumorigenesis. Due to the rarity of this disease, very few genome sequencing studies have been performed on a series of cases, especially progressive cases.

METHODS

Seven lesions from 5 patients diagnosed at the Third Affiliated Hospital of Soochow University from 2007 to 2021 were included. Clinicopathological features and prognosis/survival data were collected. Next-generation DNA sequencing was performed on six of the seven lesions.

RESULTS

In total, 3/7 (42.9%) lesions demonstrated estrogen receptor (ER) expression, including weak, moderate to strong staining, and no lesion demonstrated progesterone receptor (PR) expression. There were no cases of human epidermal growth factor (HER2) overexpression, and the Ki-67 index was low. S-100 and pan-TRK protein were diffusely positively expressed in all cases. All lesions were characterized by a t(12;15) (p13:q25) translocation, leading to ETV6-NTRK3 fusion confirmed by fluorescence in situ hybridization (FISH). The sequencing results showed that ETV6-NTRK3 fusion was the main driver of early tumorigenesis, while SBC with invasive biological behavior had more complex genomic variation in which TERT promoter mutation was detected.

CONCLUSIONS

Immunohistochemical staining of a biomarker panel, including ER, PR, HER2, Ki-67, S-100 and pan-TRK, can be used as an auxiliary diagnostic tool, and FISH detection can be used as a diagnostic tool. ETV6-NTRK3 gene fusion involving multiple sites may drive tumorigenesis, while mutations in the TERT promoter region may be a factor driving tumor progression.

Metastatic triple negative breast cancer with NTRK gene fusion on tissue but not on ctDNA molecular profile

A woman presented to medical oncology with almost 4 years of untreated, slowly progressing, triple negative metastatic breast cancer to the lung. About 15 years prior, she was diagnosed with invasive ductal carcinoma of the right breast with ipsilateral chest wall recurrence 6 years later. Comprehensive molecular profiling of a metastatic lesion detected a hotspot ETV6-NTRK3 fusion, which was not present on circulating tumour DNA or molecular profile performed 4 years prior. A second look pathological examination demonstrated tumour characteristics consistent with secretory breast carcinoma. Identification of ETV6--NKRT3 fusion allowed for treatment with larotrectinib, a tyrosine kinase inhibitor specifically indicated for secretory breast carcinoma. After 3 months, she experienced a partial response.

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.

Cytological and molecular characterization of secretory breast carcinoma

Secretory breast carcinoma is a rare neoplasm, histologically well-characterized, and secondary to ETV6-NTRK3 gene fusion, whose cytological features are scarcely described in the literature. We report the case of a woman with a history of secretory breast carcinoma 8 years before, who presented a periareolar nodule. A recurrence was diagnosed by fine-needle aspiration based on the cytomorphological features and pan-TRK immunocytochemistry on the cell block, and the patient underwent a mastectomy. The histology and molecular studies performed on the surgical specimen (immunohistochemistry, FISH and NGS) confirmed the diagnosis. Cytological smears showed abundant epithelial cellularity, in groups and single cells. These cells showed moderate atypia, with abundant cytoplasm. We observed intracytoplasmic inclusions and extracellular metachromatic globules. Immunocytochemical and immunohistochemical studies showed a triple negative breast tumour. NTRK overexpression was demonstrated with immunocytochemistry against pan-TRK on the cell block, as well as with immunohistochemistry in the surgical specimen. NTRK3 rearrangement was proved by FISH. In the primary tumour and in the recurrence, we demonstrated ETV6-NTRK3 fusion by NGS. After conducting a literature review, we have found 26 articles describing the cytological features of secretory breast carcinoma in 33 patients. The smears were described as groups of epithelial cells with vacuolated cytoplasm, single signet ring cells and a globular extracellular secretion. In only two cases molecular confirmation of the diagnosis with ETV6-NTRK3 fusion was proven, although not in the cytological specimen, but in the subsequent biopsy. The distinct cytological features of secretory breast carcinoma can help in its diagnosis, thus guiding the molecular studies. This is the first reported case that proves TRK overexpression, as a fusion surrogate, in the cytological sample.

Papillary lesions of the breast

Papillary lesions of the breast represent a heterogeneous group of lesions including benign papillomas, papillomas with focal epithelial atypia, fully fledged ductal carcinoma in situ (DCIS) or lobular neoplasia, papillary DCIS, encapsulated papillary carcinomas without or with invasion, solid papillary carcinomas, and invasive papillary carcinomas. A micropapillary pattern characterized by lack of fibrous stalks within the papillae is observed in micropapillary DCIS and invasive micropapillary carcinoma. In addition, a variety of other rare breast lesions reveals a papillary architecture such as tall cell carcinoma with reversed polarity (TCCRP) and mucinous cystadenocarcinoma, adenomyoepithelioma, and secretory carcinoma. In addition, benign lesions such as usual ductal hyperplasia, apocrine metaplasia, gynecomastia, and juvenile papillomatosis may show a papillary or micropapillary architecture. Fragments of a benign papilloma in a breast biopsy are considered a lesion of uncertain malignant potential (B3 in the European classification) and excision is mostly recommended. Although the knowledge about molecular pathology of papillary breast lesions has increased, there is not sufficient evidence for diagnostically useful molecular features, yet. The aim of this review is to provide an update on papillary and micropapillary lesions with emphasis on problematic areas for daily diagnostic work including biopsies.

Triple-Negative Breast Cancer Histological Subtypes with a Favourable Prognosis

Triple-negative breast cancers (TNBC), as a group of tumours, have a worse prognosis than stage-matched non-TNBC and lack the benefits of routinely available targeted therapy. However, TNBC is a heterogeneous group of neoplasms, which includes some special type carcinomas with a relatively indolent course. This review on behalf of the European Working Group for Breast Screening Pathology reviews the literature on the special histological types of BC that are reported to have a triple negative phenotype and indolent behaviour. These include adenoid cystic carcinoma of classical type, low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, low-grade mucoepidermoid carcinoma, secretory carcinoma, acinic cell carcinoma, and tall cell carcinoma with reversed polarity. The pathological and known molecular features as well as clinical data including treatment and prognosis of these special TNBC subtypes are summarised and it is concluded that many patients with these rare TNBC pure subtypes are unlikely to benefit from systemic chemotherapy. A consensus statement of the working group relating to the multidisciplinary approach and treatment of these rare tumour types concludes the review.

Secretory breast carcinoma in a female adult with liver metastsis: a case report and literature review

BACKGROUND

Secretory breast carcinoma is an uncommon subset of breast cancer that usually has a favorable outcome. Although initially described in children, it also occurs in adults where it may metastasize, possibly resulting in death. To date, only 20 cases of secretory breast carcinoma with distant metastases have been described.

CASE PRESENTATION

A 42-year-old female presented with liver metastasis after modified radical mastectomy of the left breast in 2008 at 34 years of age. The liver metastasis was morphologically similar to the primary tumor. Pan-TRK and Fluorescence in situ hybridization showed a rearrangement in the ETV6 gene. She subsequently underwent adjuvant chemotherapy with a fatal outcome.

CONCLUSIONS

Although secretory breast carcinoma is usually associated with favorable outcomes, our study and reviews provide a novel insight into the genetic spectrum and treatment of secretory breast carcinoma showing reduced expression of hormone receptors, abnormal genomic profiles, and possible poor prognosis. Targeted therapy may curb clinically aggressive cases. Additional molecular investigations are needed to determine the links between specific mutations and poor prognosis.

Hypofractionated radiation in secretory breast cancer: A case report

Secretory carcinoma is a rare and indolent breast cancer with a lack of established treatment paradigms. We describe a case of a woman who underwent breast conservative therapy in the modern era. A 48 year old woman with a screen-detected left breast cancer was found to have early-stage secretory carcinoma after definitive breast conservation surgery. Further management with adjuvant radiation was recommended. After definitive breast conservative surgery, final pathology was notable for secretory breast carcinoma due to the immunohistologic characteristics of the tumor, ETV6-NTRK3 gene fusion, and histologic findings. After multi-disciplinary discussion, it was recommended that the patient proceed with adjuvant radiation. She was treated using a modestly hypofractionated regimen of 4256 cGy in 16 fractions. She tolerated the treatment well, developing only grade 1 radiation dermatitis. At 1 year follow-up she was clinically and radiographically free of disease. With a shift in management toward breast conservative therapy, defining the role of adjuvant radiation for secretory carcinomas in the modern era is of increasing importance. Modestly hypofractionated radiation is well-tolerated. Oncologic outcomes will be assessed with continued long-term follow-up.

Clinicopathologic profiling and oncologic outcomes of secretory carcinoma of the breast

Secretory carcinoma of the breast (SCB) is a rather rare entity of invasive breast cancer, the clinicopathologic characteristics and survival outcomes remain to be elaborated. A retrospective review was conducted in SEER database. A total of 190 SCB patients identified in SEER were eligible for inclusion in the analysis. Median age at diagnosis was 56 years (range 2–96 years). Both sexes and bilateral breast could be affected. Intriguingly, the incidence of SCB tended towards to decreasing in recent decades. Small tumor burden was observed with a mean tumor size of 2.13 cm. In a subgroup with sufficient details, positive staining of estrogen receptor (ER) and progesterone receptor (PR) was 58% and 40%, respectively. The vast majority of patients were of well to moderate differentiation (86.86%) and negative regional lymph nodes involvement (70.71%). Nearly half of the patients took radiotherapy and chemotherapy. Seniors were inclined to have an inferior breast cancer specific survival (BCSS) than their younger counterparts (P = 0.018). Patients underwent breast conserving surgery (BCS) and radiotherapy had much better BCSS than its mastectomy counterparts (P = 0.014). Collectively, SCB is a clinical indolent invasive breast cancer with excellent prognosis. BCS in conjunction with radiotherapy would be a rational alternative for this distinct entity.

Secretory carcinoma of the breast with multiple distant metastases in the brain and unfavorable prognosis: a case report and literature review

Background

Secretory carcinoma of the breast is one of the rarest entities, accounting for less than 0.15 % of all infiltrating breast carcinomas. It has characteristic histopathological and molecular features and, in general, a more favorable prognosis. In this case report, we describe a local, advanced secretory carcinoma of the breast with aggressive course and an unfavorable outcome.

Case presentation

A hard, painless, and palpably bossed mass approximately 12.0 cm in diameter occupied most of the left breast of a 39-year-old woman with fixation to the overlying skin. Breast ultrasonography and magnetic resonance imaging (MRI) scans gave the same grading as BI-RADS IV. A needle biopsy was performed, and the pathological diagnosis was secretory carcinoma. Neoadjuvant chemotherapy (NAC) was then performed, after which ultrasonography and MRI scans revealed chemo-resistance of the tumor to NAC. Left breast mastectomy and axillary lymphadenectomy were subsequently performed. Tumor cells were triple-negative and positive for S-100 and periodic acid-Schiff (PAS) staining. Fluorescence in-situ hybridization (FISH) analysis indicated a fusion arrangement of the ETV6-NTRK3 gene. The patient developed multiple distant metastases in the brain and died of these metastases 19 months after initial diagnosis.

Conclusions

Secretory carcinomas of the breast have been described as a low-grade histologic subtype with a favorable prognosis. This case showed chemo-resistance to neoadjuvant chemotherapy, multiple distant metastases, and a final unfavorable outcome. Further research is needed to better understand the behavior and treatment of this rare tumor.

Secretory carcinoma of the breast limited to the dermis: Cutaneous or breast primary?

We offer a case of a 22-year-old woman who presented with a painless breast mass. Physical examination of the breast was unrevealing other than a palpable mass in close proximity to the nipple areolar region. No lymphadenopathy was noticed in the axilla or supraclavicular region. Sonographic assessment was performed and the findings were classified as Breast Imaging Reporting and Data System category 4. Because of the proximity of the mass to the skin surface, an excisional biopsy was performed. Final pathology disclosed a 5-mm invasive carcinoma. On pathologic examination, histopathologic and immunophenotypes supported the diagnosis of secretory carcinoma; however, whether the origin was from the breast parenchyma or skin tissue was not clearly discernable. Therefore, the patient was scheduled for sentinel lymph node biopsy with plans for axillary dissection if positive. While the overall prognosis for secretory carcinoma is good, with a low chance of metastasis, any ambiguity in breast mass diagnosis should be discussed in a multidisciplinary tumor board and should be treated aggressively particularly in younger patients.

Rare Breast Cancer Subtypes

PURPOSE OF REVIEW

Breast cancer is a collection of diseases including the more common invasive ductal and lobular carcinomas and rarer subtypes of breast cancer. This review summarizes the features of rare breast cancers.

RECENT FINDINGS

Each of the rare tumors has defined pathological and clinical features that impact treatment recommendations. In this review, we summarize these for each rare type of breast cancer and where available we include molecular features of each tumor. Rare subtypes of breast cancer each have unique features. In many cases, data is limited for the optimal treatment approaches.

Secretory carcinoma of the breast, commonly exhibits the features of low grade, triple negative breast carcinoma- A Case report with updated review of literature

Secretory carcinoma of the breast (SBC) is a rare breast neoplasm. Most of the patients present at an early stage with a relatively indolent clinical course. Lymph node and distant metastasis are also very infrequent. The histomorphological features of the secretory breast carcinoma are quite characteristic. Predominantly three histological patterns, solid, microcystic, and tubular, have been noted with copious amounts of intra and extracellular secretory material. Most commonly, no positivity for estrogen receptor (ER), progesterone receptor (PR) and ERBB2(HER2/neu) is observed in SBCs. As SBC can occasionally be hormone receptor-positive, they should not be categorized in the triple-negative breast carcinoma (TNBC) group in general. A very characteristic genetic translocation t (12;15) has been noted in this rare tumor, resulting in a fusion between ETV6 and NTRK3 proteins. We present a case of a 60-year-old lady who presented with right breast lump of 1-month duration and was managed by lumpectomy and sentinel lymph node dissection. Axillary dissection was not performed because the sentinel lymph node biopsy was negative. Postoperative radiotherapy was given to the right breast with a boost to the tumor bed. No adjuvant chemotherapy was given No recurrence has been noted even after a year of the completion of treatment

Neurotrophic receptor tyrosine kinase (NTRK) fusions and their role in cancer

Neurotrophic receptor tyrosine kinase (NTRK) fusions are rare, therapeutically actionable, and, in some cases, diagnostic oncogenic events that can occur in a variety of adult and pediatric cancers. Cytopathologists need to be a familiar with the types of tumors that can harbor NTRK fusions to triage specimens accordingly for testing.

Triple negative breast cancer: special histological types and emerging therapeutic methods

Triple negative breast cancer (TNBC) is a complex and malignant breast cancer subtype that lacks expression of the estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), thereby making therapeutic targeting difficult. TNBC is generally considered to have high malignancy and poor prognosis. However, patients diagnosed with certain rare histomorphologic subtypes of TNBC have better prognosis than those diagnosed with typical triple negative breast cancer. In addition, with the discovery and development of novel treatment targets such as the androgen receptor (AR), PI3K/AKT/mTOR and AMPK signaling pathways, as well as emerging immunotherapies, the therapeutic options for TNBC are increasing. In this paper, we review the literature on various histological types of TNBC and focus on newly developed therapeutic strategies that target and potentially affect molecular pathways or emerging oncogenes, thus providing a basis for future tailored therapies focused on the mutational aspects of TNBC.

Genotype-phenotype associations in breast pathology: Achievements of the past quarter century

The first genotype-phenotype relationship in breast pathology developed in 1994 with the discovery of the CDH1 gene. This finding eventually provided biological insight into the characteristic morphology of invasive lobular carcinoma. Subsequent investigative efforts have uncovered additional molecular alterations largely responsible for the histology of several breast neoplasms including secretory carcinoma, adenoid cystic carcinoma, tall cell carcinoma with reversed polarity, fibroepithelial lesions, and most recently, adenomyoepithelioma. Evaluation of the genomic landscape of other special types of breast cancer with distinctive growth patterns, such as invasive mucinous carcinoma, have yet to uncover recurring cytogenetic and/or molecular alterations. Despite the lack of a hallmark alteration in mucinous carcinoma, it is important to note the relative decrease in PIK3CA mutations compared with invasive carcinoma of no special type. In this review, we describe the clinical and pathologic features of breast tumors with recognized genotype-phenotype correlations and summarize the molecular alterations of mucinous carcinoma.

[Multicentric secretory carcinoma of the breast: Case report and review of the literature]

Secretory carcinoma of the breast is a rare entity, characterized by the presence of intra- and extracellular, eosinophilic and acelular secretions. They are negative for hormone receptors and do not express human epidermal growth factor receptor HER-2/neu. However, the clinical outcome is favorable. Multicentricity is very unusual. We report a case of a 32-year-old woman with a multicentric secretory carcinoma of the breast. The main pathological features are discussed together with a review of the pertinent literature.

Pan-TRK Immunohistochemistry: A Useful Diagnostic Adjunct For Secretory Carcinoma of the Breast

Secretory carcinoma is a special-type breast carcinoma underpinned by a recurrent t(12;15)(p13;q25) translocation resulting in ETV6-NTRK3 gene fusion. Immunohistochemistry (IHC) using a pan-TRK antibody has been recently shown to help identify NTRK rearrangements in other tumor types. The purpose of this study was to assess the diagnostic utility of pan-TRK IHC in secretory carcinoma of the breast. Pan-TRK IHC was performed using a rabbit monoclonal antibody on whole sections of 24 breast secretory carcinomas and tissue microarray sections of other breast carcinoma types (n=203) and histologic mimics (n=15). Cases were assessed for staining intensity and localization. The 24 patients with secretory carcinoma had a median age of 44 years and a median tumor size of 1.0 cm. ETV6 fluorescence in situ hybridization was positive in all cases tested (n=20). Twenty-three cases (95.8%) showed staining with pan-TRK, which was exclusively nuclear in 19, primarily nuclear with weak cytoplasmic staining in 3, and primarily cytoplasmic with focal nuclear staining in 1. The nuclear staining was diffuse in 17 and at least focally strong in 17. The only pan-TRK negative case was a core biopsy with limited tumor. Among the 203 nonsecretory carcinomas, 21 (10.3%) showed focal, weak nuclear staining in <5% of tumor cells and 1 (0.5%) showed focal membranous staining. All histologic mimics were negative. In conclusion, diffuse and/or at least focally strong nuclear pan-TRK staining is a sensitive and specific marker for secretory carcinoma of the breast.

Pure secretory carcinoma in situ: a case report and literature review

Background

Secretory breast carcinoma is an exceptionally rare type of breast carcinoma. Only 5 cases of pure secretory carcinoma in situ have been reported in English literature. Herein, we reported a rare case of pure secretory breast carcinoma in situ.

Case presentation

The patient is a 38-year-old female with bloody discharge from the left nipple. Microscopically, the terminal-duct lobular units were enlarged and filled with tumor cells. The tumor cells were arranged in cystic, microcystic, solid and papillary pattern and formed a honeycomb-like appearance. The presence of intracellular and extracellular eosinphilic PAS-positive material was the most remarkable feature. Immunohistochemically, myoepithelial markers highlighted the complete presence of myoepithelial cells around the tumour nests. Tumour cells were strongly positive for S-100 and CK5/6, negative for ER, PR and HER2. Fluorescence in situ hybridization analysis showed ETV6-NTRK3 fusion.

Conclusion

Secretory carcinoma in situ shares the same morphological, immunohistochemical and molecular features with invasive secretory carcinoma except that the papillary growth pattern is more common in the introductal components. Cautions should be taken to distinguish secretory carcinoma in situ from other introductal lesions. Our report is an important supplement to the morphology spectrum of secretory breast carcinoma.

Secretory carcinoma of the breast: clinicopathologic profile of 14 cases emphasising distant metastatic potential

AIMS

Secretory carcinoma of the breast (SCB) is a rare histological type of breast carcinoma with a generally indolent clinical behaviour. We aim to elucidate the clinical, pathological and molecular findings of SCB cases and identify characteristics associated with aggressive clinical courses.

METHODS AND RESULTS

Fourteen patients with SCB were identified, including 12 women and two men, with a median age of 56 years (range = 8-81 years). Clinical data, histological diagnosis, molecular findings and follow-up were reviewed. Eight patients presented with palpable masses and four patients with radiographic abnormalities. All cases were unilateral. Surgical procedures included excisional biopsies and ipsilateral mastectomies. In 10 cases, oestrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) results were obtained, with six cases positive for ER and three positive for PR. All cases lacked HER2 overexpression. Sentinel lymph node biopsy was performed in 10 cases, and two patients had axillary lymph node metastasis. Follow-up ranged from 21 to 212 months (median = 70 months). Two patients developed distant metastasis of SCB. Molecular analysis of these aggressive tumours revealed amplification of the 16p13.3 locus, a TERT promotor mutation and loss of 9p21.3 locus. Review of the literature for SCB cases with distant metastasis was performed.

CONCLUSIONS

Although SCBs are generally associated with a favourable prognosis, our study and review demonstrate that a subset of SCBs may develop distant metastases. Further studies are warranted to identify markers predictive of more aggressive clinical behaviour in this rare breast cancer subtype.

Clinicopathologic and molecular characteristics of 44 patients with pure secretory breast carcinoma

Objective

Secretory breast carcinoma (SBC) is a rare type of breast malignancy, accounting for less than 0.02% of all infiltrating breast malignancies. The pure SBC, a type of SBC without another type of breast malignant neoplasm, is particularly rare. This study aimed to investigate the clinicopathologic and molecular features of pure SBC.

Methods

The main pathological parameters such as estrogen receptor (ER), progesterone receptor (PR), and human epithelial growth factor receptor 2 (C-erbB-2) were detected by immunohistochemistry (IHC), and the clinicopathologic and prognostic difference were compared with invasive ductal carcinoma (IDC). Fluorescent in situ hybridization (FISH) and reverse transcription polymerase chain reaction (RT-PCR) was performed to identify the ETV6-NTRK3 rearrangement of SBC.

Results

We found that the positivity rates of ER, PR, C-erbB-2, p53, and S-100 were 47.7% (21/44), 52.3% (23/44), 36.4% (16/44), 27.3% (12/44), and 95.5% (42/44), respectively, which were higher than those reported in previous studies. Special periodic acid-Schiff analysis was performed in 36 patients, and the value of the Ki-67 index ranged from 1% to 50% (mean value: 10%). Interestingly, most patients with pure SBC harbored an ETV6-NTRK3 rearrangement with an 88.6% (39/44) expression rate. Compared with IDC, the tumor size of most patients with SBC was larger than 2 cm (P = 0.024). Ultrasound showed benign lesions, and the total misdiagnosis rate was higher (P = 0.020). Although the pathological classification was mostly triple-negative breast cancers (P = 0.036), there was less metastasis (P = 0.029), and the overall prognosis was better than that of the IDC group.

Conclusions

Although axillary lymph node metastasis, local recurrence, or distant metastasis may occur, SBC is also considered an indolent neoplasm with a good prognosis. Once diagnosed, surgical treatment should be performed as soon as possible, followed by appropriate adjuvant chemotherapy, irradiation, and endocrine therapies.

Secretory Carcinoma of the Breast in a 20-year-old Male: Case Report and Review of Literature

Secretory breast carcinoma (SBC) is a very rare low-grade subtype of breast carcinoma. It was initially termed “juvenile breast cancer,” but it is now known to occur in adults of both sexes, and only few male cases have been reported in the literature. SBC is of importance because of its unique morphology and excellent prognosis. We report here a case in a 20-year-old male presenting with right pedunculated and ulcerated breast mass with associated contact bleeding. Histopathology was performed and it revealed a secretory carcinoma. This tumor is morphologically characterized by the presence of abundant eosinophilic secretions in intracellular vacuoles and intercellular spaces. The objective of this article is to review the epidemiological and clinical aspect of secretory carcinoma from a case report and literature review.

Molecular Classification of Breast Cancer

Breast cancer is a heterogeneous disease, observed traditionally by morphology and protein expression but, more recently with the advent of modern molecular technologies, at the genomic and transcriptomic level. This review describes the association between the different molecular subtypes with the histologic subtypes of breast cancer alongside some of their major genomic characteristics and illustrates how these subtypes may affect the appearance of tumors on imaging studies. The authors aim to show how molecular stratification can be used to augment traditional methods to improve our understanding of breast cancers and their clinical management.

De-escalating systemic therapy in triple negative breast cancer: The example of secretory carcinoma

Triple negative breast cancers have the highest relapse risk and the least favourable prognosis of all breast cancer subtypes, leading to an escalation of chemotherapy, substantially during recent years. Secretory carcinoma of the breast is a rare triple negative neoplasm, first described in children but more often presenting in adults. We report a case of a 70-years-old woman, initially diagnosed on the biopsy with a triple negative infiltrating Not Otherwise Specified (NOS) carcinoma of the breast, before it was later correctly identified as a secretory carcinoma, notably because of an abundant intra and extracellular secretory material. This new diagnosis, confirmed by fluorescence in-situ hybridization analysis showing ETS variant 6 (ETV6) gene rearrangement, allowed the de-escalation of chemotherapy therapy. Four years later, the patient is free of recurrences.

Genotype-Phenotype Correlations in Breast Cancer

Only a few breast cancer histologic subtypes harbor distinct genetic alterations that are associated with a specific morphology (genotype-phenotype correlation). Secretory carcinomas and adenoid cystic carcinomas are each characterized by recurrent translocations, and invasive lobular carcinomas frequently have CDH1 mutations. Solid papillary carcinoma with reverse polarity is a rare breast cancer subtype with a distinctive morphology and recently identified IDH2 mutations. We review the clinical and pathologic features and underlying genetic alterations of those breast cancer subtypes with established genotype-phenotype correlations and discuss the phenotypes associated with germline mutations in genes associated with hereditary breast cancer.