Morphogenesis of the papillary lesions of the breast: phenotypic observation

Invasive papillary carcinoma of the breast

Invasive papillary carcinoma is a rare form of breast cancer that is more likely to occur in postmenopausal women. Previous studies have been limited to case reports and small retrospective studies, leading to low awareness of this type of tumor and difficult clinical management. According to the available literature, invasive papillary carcinoma exhibits unique pathological features and biological behaviors. Invasive papillary carcinoma is mostly luminal type, with a low rate of lymph node metastasis, which underlies its favorable prognosis. The effectiveness of adjuvant therapy in reducing tumor burden and improving prognosis in patients with invasive papillary carcinoma remains uncertain. Due to the rarity of the lesion, conducting prospective clinical trials is impractical. The use of biological models, such as organoids, can help alleviate the impact of the scarcity of this condition on research. In addition, invasive papillary carcinoma is affected by specific genomic events, and more extensive studies of gene expression profiling may provide molecular-level insights to make optimal therapeutic decisions.

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.

Pathology of breast papillary neoplasms: Community hospital experience

In this study, 550 breast papillary neoplasms collected in a community hospital over more than ten years were reviewed and analyzed. This included 457 intraductal papillomas, 53 papillary carcinomas, 35 papillary DCIS and five invasive papillary carcinomas. The diagnostic rate of papillary neoplasms increased over time, likely due to better recognition by pathologists. Intraductal papillomas occurred most frequently in the upper outer quadrants and contained ADH/DCIS in 19% of cases. A total of 28% of non-incidental papillomas were associated with ADH/DCIS, and 29% of patients with papillomas had ADH/DCIS in adjacent tissue; nearly half of papillomas that were > 1 cm in size contained ADH/DCIS in the papilloma or adjacent to it. No single feature could predict an upgrade on excision for non-atypical intraductal papillomas diagnosed on core biopsy. There was no significant difference in the association of ADH/DCIS with central or peripheral papillomas. The overall upgrade rate of non-atypical intraductal papillomas to DCIS on excision was 2%, which justifies the conservative management of non-atypical sub-centimeter lesions. Papillary carcinomas occurred in older than intraductal papilloma patients and were most frequent in the upper quadrants. Although classically devoid of a myoepithelial cell layer, papillary carcinomas may contain some residual or even an ample myoepithelial cell layer in the papillae. An association between papillary carcinoma and conventional invasive carcinoma was found in 40% of EPCs and 89% of SPCs. Papillary DCIS was usually low- or intermediate-grade. The presence of a myoepithelial cell layer in the papillae was not inconsistent with this diagnosis. Invasive papillary carcinoma may have two histologic patterns: papillary and cribriform.

Breast cancer intratumour heterogeneity: current status and clinical implications

Breast cancer (BC) is a heterogeneous disease that varies in presentation, morphological features, behaviour, and response to therapy. High-throughput molecular profiling studies have revolutionised our understanding of BC heterogeneity, and have demonstrated that molecular profiles of tumours are variable not only between tumours, but also within individual tumours. Current evidence indicates that spatial and temporal intratumour heterogeneity of BC exists at levels beyond what are commonly expected. Intratumour heterogeneity poses critical challenges in the diagnosis, prediction of behaviour and management of BC. For instance, heterogeneous expression of oestrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 can be seen not only in primary tumours between different regions, but also between primary tumours and their corresponding metastatic/recurrent lesions. The demonstration of molecularly distinct subclones within individual tumours may explain, at least in part, the mechanisms controlling the variable behaviour of BC, and may change our approach to BC sampling and treatment. In this review, BC intratumour heterogeneity is highlighted, with a special emphasis on the current knowledge pertaining to the relationship between intratumour heterogeneity and BC pathogenesis, evolution, and progression, with consideration of its impact on disease diagnosis, management, and the emergence of novel therapeutic targets. The key role of high-throughput molecular and imaging techniques is also addressed.

Predictive Factors for Upgrading Patients with Benign Breast Papillary Lesions Using a Core Needle Biopsy

PURPOSE

Intraductal papilloma (IDP) is a benign breast disease with malignant potential, for which complete surgical excision is usually recommended. The aim of the present study was to investigate predictive factors for upgrading patients with a benign papillary lesion (BPL).

METHODS

This study was an observational study using a prospectively collected cohort. In total, 13,049 patients who underwent a core needle biopsy (CNB) for a breast lesion between January 2009 and May 2015 were enrolled. We reviewed all patients with pathologically confirmed BPL from a CNB.

RESULTS

Surgical treatment was performed for 363 out of a total of 592 lesions. According to the pathological differences, the lowest upgrade rate was shown in IDP without atypia (without atypia, 6.0%; with atypia, 26.8%; papillary neoplasm, 31.5%; p<0.001). The univariate analysis showed that, in IDP without atypia, the age at diagnosis, size of BPL on ultrasonography, and density on mammography were associated with upgrading. The multivariate analysis revealed that age >54 years and lesion size >1 cm were significantly associated with upgrade to malignancy (odds ratio [OR]=4.351, p=0.005 and OR=4.236, p=0.001, respectively).

CONCLUSION

The indications for surgical treatment can be defined as age >54 years and mass size >1 cm, even in IDP without atypia in the CNB results; this also includes cases of IDP with atypia or papillary neoplasm. Therefore, we suggest that close observation without surgery is sufficient for younger women with a small IDP without atypia.

Papillary carcinoma of the breast: diagnostic agreement and management implications

AIMS

Papillary carcinoma (PC), which is a rare type of breast cancer, comprises a heterogeneous group of tumours. The diagnostic categorization of PC as in-situ and invasive disease remains a matter of debate with respect to interpretation of its overlapping histological features, and with respect to the uncertainty in clinical behaviour that this dilemma raises. The aim of this study was to assess the diagnostic agreement regarding PC among reporting breast pathologists.

METHODS AND RESULTS

Six cases of PC included in the UK National Health Service Breast Screening Programme breast pathology interpretive external quality assurance scheme in the last 10 years were reviewed. In this scheme, one representative haematoxylin and eosin-stained slide from each case is circulated to an average of 600 participants. Data on diagnostic categories were collected and slides were reviewed according to the World Health Organization (WHO) diagnostic criteria. The number of final diagnoses of malignancy (in situ or invasive) was highest for invasive PC (99% of the participants diagnosed it as malignant), followed by solid PC (94% and 95%, respectively), encapsulated PC (92% and 92%, respectively), and papillary ductal carcinoma in situ (DCIS) (88%). Most cases of papillary DCIS were correctly classified as in-situ disease (77%), but 28% of the participants classified invasive PC cases as in-situ disease. Of the participants, 24% reported encapsulated PC as invasive disease. Of the two solid PC cases, one showed some features consistent with the WHO description of invasive solid PC, whereas the other showed features of classic (non-invasive) solid PC. Both cases were reported as invasive by 75% and 77% of participants, respectively. Breast specialists more frequently classified PC as an in-situ carcinoma than did non-specialist participants, and the difference was significant (P = 0.013).

CONCLUSIONS

Recognition of PC as a malignant entity (in situ or invasive) is high, but concordance of its classification into in-situ and invasive disease is low. Histological features that can define invasion in PC should be better defined. These rare lesions require additional diagnostic work-up, and difficult cases should trigger consensus opinion or expert referral.