Modern therapies and iatrogenic changes in breast pathology

A rare case: synchronous ipsilateral breast implant-associated anaplastic large cell lymphoma and invasive ductal carcinoma

A 78-year-old female with a history of cosmetic breast implants presented with unilateral breast enlargement and was subsequently diagnosed with stage IA breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) as well as stage IB ipsilateral synchronous invasive ductal carcinoma (IDC). Her assessment included bilateral breast ultrasounds,mammograms and MRIs with right-sided fine needle aspiration of peri-implant fluid, core biopsy of right breast mass and a whole-body positron emission tomography scan. She was surgically treated with bilateral capsulectomy, implant removal and mastectomy. No adjuvant treatment was required for the BIA-ALCL. The IDC required adjuvant chemotherapy, radiotherapy and endocrine therapy. This rare case highlights the paramount importance of thorough evaluation of suspected BIA-ALCL patients for synchronous breast pathologies. We conclude with a concise summary of the salient points on evaluation and management of BIA-ALCL for surgeons.

Pathology of neoadjuvant therapy and immunotherapy testing for breast cancer

Neoadjuvant chemotherapy (NACT) has become the standard of care for high-risk breast cancer, including triple-negative (TNBC) and HER2-positive disease. As a result, handling and reporting of breast specimens post-NACT is part of routine practice, and it is important for pathologists to recognise the changes in tumour cells, tumour-associated stroma and background breast tissue induced by NACT. Familiarity with characteristic stromal features enables identification of the pre-treatment tumour site and allows confident diagnosis of pathological complete response (pCR) which is important for decisions concerning adjuvant therapy. Neoadjuvant endocrine therapy (NAET) is used less frequently than NACT; however, the SARS-COVID-19 pandemic has changed practice, with increased use as bridging therapy if surgery is delayed. NAET also induces characteristic changes in the tumour and stroma. Changes in the tumour microenvironment following NACT and NAET are also described. Immunotherapy is approved for use in advanced TNBC, and there are several trials exploring its role in early TNBC in the neoadjuvant setting. The current biomarker to determine eligibility for treatment with immune checkpoint inhibitors is programmed death ligand-1 (PD-L1) immunohistochemistry; however, this is complicated by lack of standardisation with different drugs linked to tests using different antibodies with different scoring systems. The situation in the neoadjuvant setting is further complicated by improved pCR rates for PD-L1-positive tumours in both immune therapy and placebo arms. Alternative biomarkers are urgently needed to identify which patients will derive benefit from immunotherapy and key candidates are discussed.

Intraductal administration of transferrin receptor-targeted immunotoxin clears ductal carcinoma in situ in mouse models of breast cancer-a preclinical study

The human transferrin receptor (TFR) is overexpressed in most breast cancers, including preneoplastic ductal carcinoma in situ (DCIS). HB21(Fv)-PE40 is a single-chain immunotoxin (IT) engineered by fusing the variable region of a monoclonal antibody (HB21) against a TFR with a 40 kDa fragment of Pseudomonas exotoxin (PE). In humans, the administration of other TFR-targeted immunotoxins intrathecally led to inflammation and vascular leakage. We proposed that for treatment of DCIS, intraductal (i.duc) injection of HB21(Fv)-PE40 could avoid systemic toxicity while retaining its potent antitumor effects on visible and occult tumors in the entire ductal tree. Pharmacokinetic studies in mice showed that, in contrast to intravenous injection, IT was undetectable by enzyme-linked immunosorbent assay in blood following i.duc injection of up to 3.0 μg HB21(Fv)-PE40. We demonstrated the antitumor efficacy of HB21(Fv)-PE40 in two mammary-in-duct (MIND) models, MCF7 and SUM225, grown in NOD/SCID/gamma mice. Tumors were undetectable by In Vivo Imaging System (IVIS) imaging in intraductally treated mice within 1 wk of initiation of the regimen (IT once weekly/3 wk, 1.5 μg/teat). MCF7 tumor-bearing mice remained tumor free for up to 60 d of observation with i.duc IT, whereas the HB21 antibody alone or intraperitoneal IT treatment had minimal/no antitumor effects. These and similar findings in the SUM225 MIND model were substantiated by analysis of mammary gland whole mounts, histology, and immunohistochemistry for the proteins Ki67, CD31, CD71 (TFR), and Ku80. This study provides a strong preclinical foundation for conducting feasibility and safety trials in patients with stage 0 breast cancer.

Neoadjuvant Therapy in Breast Cancer: Histologic Changes and Clinical Implications

Cytotoxic or endocrine therapy before surgery (neoadjuvant) for breast cancer has become standard of care, affording the opportunity to assess and quantify response in the subsequent resection specimen. Correlation with radiology, cassette mapping, and histologic review with a semi-quantitative reporting system such as residual cancer burden (RCB) provides important prognostic data that may guide further therapy. The tumor bed should be identified histologically, often as a collagenized zone devoid of normal breast epithelium, with increased vasculature. Identification of residual treated carcinoma may require careful high power examination, as residual tumor cells may be small and dyscohesive; features are widely variable and include hyperchromatic small, large, or multiple nuclei with clear, foamy, or eosinophilic cytoplasm. Calculation of RCB requires residual carcinoma span in 2 dimensions, estimated carcinoma cellularity (% area), number of involved lymph nodes, and span of largest nodal carcinoma. These RCB parameters may differ from AJCC staging measurements, which depend on only contiguous carcinoma in breast and lymph nodes.

Breast Implant-Associated Anaplastic Large-Cell Lymphoma: Current Understanding and Recommendations for Management

Worldwide, millions of women live with breast implants. Therefore, it is important that physicians be aware of an uncommon but possibly serious complication arising from breast implants: breast implant-associated anaplastic large cell lymphoma (BIA-ALCL). Breast implant-associated anaplastic large-cell lymphoma most commonly presents as a delayed fluid collection around a textured breast implant or as a mass in the capsule surrounding the implant. The exact pathogenesis of the disease remains unclear. The neoplastic cells of BIA-ALCL show strong uniform staining for CD30 and are consistently negative for activin receptor-like kinase 1. Patients with confirmed cases should be referred to a lymphoma specialist or breast medical oncologist for a complete oncologic evaluation before any surgical intervention. For disease confined to the fluid accumulation or capsule, or both, surgical removal of the implant and complete capsulectomy is the preferred treatment. Postoperative chemotherapy or radiation, or both, are not considered necessary for patients with limited-stage disease and are reserved for advanced disease stages. Generally, BIA-ALCL is a local disease that follows an indolent course and has an excellent prognosis. Although complete remission of disease has occurred in patients with BIA-ALCL, median overall survival is reduced. As of March 2018, approximately 529 unique, confirmed BIA-ALCL cases had been reported in 23 countries. To date, 16 patients have died from BIA-ALCL, and all had extracapsular involvement. The aim of this article is to summarize the diagnosis, evaluation, and management of BIA-ALCL, based on established guidelines, for all practitioners who may care for patients with breast implants.

Artifactual Displacement of Ductal Carcinoma In Situ (ADDCIS) (Toothpaste Effect): A Mimicker of Invasive Ductal Carcinoma

Needle tract displacement is a recognized mimicker of invasive ductal carcinoma (IDC). Artifactual displacement of ductal carcinoma in situ (ADDCIS) unassociated with needle tracts may occur secondary to mechanical compression of breast specimens but has not been systematically studied. We identified 16 cases of ADDCIS unassociated with needle tract changes; the majority (75%) were internal referrals to the breast pathology service to rule out IDC, 19% were received as external diagnostic consultations to rule out IDC, and 6% were routine second review cases originally diagnosed as IDC at an outside hospital. The majority (62.5%) of ADDCIS occurred in lumpectomies, whereas 25% occurred in mastectomies and 12.5% in core biopsies. ADDCIS foci ranged from <1 to 5 mm; however, all ADDCIS spanning >4 mm demonstrated a linear pattern of displacement. In all cases, ADDCIS involved mammary stroma in a nonlobular distribution; in half, ADDCIS extended between benign lobules. Immunohistochemistry revealed no myoepithelial cells around the ADDCIS (n=7), adding to the concern for IDC. However, in contrast to most IDC, ADDCIS lacked stromal reaction and showed degenerative, smudged chromatin. None of the 9 patients with significant follow-up (mean, 7 y) developed metastasis. All received further local therapy for DCIS (5 radiation, 4 completion mastectomy); 1 received adjuvant systemic therapy (hormone therapy for contralateral IDC). In conclusion, ADDCIS mimics IDC, particularly given its permeative pattern and absence of myoepithelial cells. ADDCIS is most common in lumpectomies but can occur in mastectomies or core biopsies. Diagnostic clues include smudged nuclear chromatin, lack of stromal response, and linear pattern of displacement in larger lesions. The benign follow-up without systemic therapy supports our view that ADDCIS does not represent true IDC.

Expression of hormone receptors in low-grade adenosquamous carcinoma of the breast: A case report

RATIONALE

Low-grade adenosquamous carcinoma (LGASC) is a rare subtype of metaplastic breast carcinoma which is generally recognized as a characteristic subgroup of triple-negative breast cancers previously. However, in this study, we reported for the first time a case of LGASC with hormone receptors expression.

PATIENT CONCERNS

Pathological analysis of breast tumor specimen obtained by a 42-year-old female patient was performed. Morphologically, it composed of glandular structures with scattered squamous differentiation accompanied by haphazard arrangement of spindle cell stroma. Immunohistochemically, all myoepithelial and squamous differentiation markers showed typical LGASC positive or negative staining pattern. Interestingly, we found that normally aberrant hormone receptors were reactivated in this case. To our knowledge, this is the first report of a hormone receptor-positive LGASC. Apart from this, in the extended resection sample, we found scattered squamous metaplasia and florid adenosquamous proliferation (ASP). Meanwhile, it was positive for CD44 variant isoforms (CD44v), which is a breast cancer stem cell (CSC) marker, and expressed in LGASC, squamous metaplasia, and ASP.

DIAGNOSIS

LGASC with hormone receptors expression.

INTERVENTIONS

The breast-extended local excision and axillary lymph node dissection were performed.

OUTCOMES

The patient was free of local recurrence and distant metastasis 6 months after surgical resection.

LESSONS

We herein report the first case of LGASC with immunoreactivity for hormone receptors, expanding its profile of immunophenotypes. CD44v may play an important role in the transition of LGASC precursor lesions into malignant processes, which may serve as a therapeutic target in LGASC.