Is it ductal carcinoma in situ with microinvasion or "Ductogenesis"? The role of myoepithelial cell markers

Improving the diagnosis of ductal carcinoma in situ with microinvasion without immunohistochemistry: An innovative method with H&E-stained and multiphoton microscopy images

Ductal carcinoma in situ with microinvasion (DCISM) is a challenging subtype of breast cancer with controversial invasiveness and prognosis. Accurate diagnosis of DCISM from ductal carcinoma in situ (DCIS) is crucial for optimal treatment and improved clinical outcomes. However, there are often some suspicious small cancer nests in DCIS, and it is difficult to diagnose the presence of intact myoepithelium by conventional hematoxylin and eosin (H&E) stained images. Although a variety of biomarkers are available for immunohistochemical (IHC) staining of myoepithelial cells, no single biomarker is consistently sensitive to all tumor lesions. Here, we introduced a new diagnostic method that provides rapid and accurate diagnosis of DCISM using multiphoton microscopy (MPM). Suspicious foci in H&E-stained images were labeled as regions of interest (ROIs), and the nuclei within these ROIs were segmented using a deep learning model. MPM was used to capture images of the ROIs in H&E-stained sections. The intensity of two-photon excitation fluorescence (TPEF) in the myoepithelium was significantly different from that in tumor parenchyma and tumor stroma. Through the use of MPM, the myoepithelium and basement membrane can be easily observed via TPEF and second-harmonic generation (SHG), respectively. By fusing the nuclei in H&E-stained images with MPM images, DCISM can be differentiated from suspicious small cancer clusters in DCIS. The proposed method demonstrated good consistency with the cytokeratin 5/6 (CK5/6) myoepithelial staining method (kappa coefficient = 0.818).

Encapsulated Papillary Carcinoma of the Breast: A Review of Clinicopathologic Characteristics, Molecular Mechanisms, and Patient Management

Encapsulated papillary carcinoma (EPC) represents a distinct entity within the spectrum of breast papillary tumors, typically manifesting as a retroareolar mass. This rare subtype can be effectively visualized using ultrasound and magnetic resonance imaging, which reveal characteristic cystic-solid nodules. Histopathologically, EPC is defined by a papillary tumor structure with a well-defined fibrous capsule, devoid of myoepithelial cells both within and around the capsule. Immunohistochemical staining for myoepithelial markers is essential to confirm the absence of these cells, thereby validating the diagnosis of EPC. At the molecular level, EPC exhibits feature similar to estrogen receptor-positive invasive ductal carcinoma (IDC), with a biological behavior that lies between ductal carcinoma in situ (DCIS) and IDC. Generally, EPC has a favorable prognosis, associated with minimal recurrence and metastatic potential. Therapeutic strategies for EPC may parallel those for DCIS, including surgical excision. Adjuvant radiotherapy is recommended following surgery for patients with concurrent DCIS or those who have undergone breast-conserving therapy. In cases with associated IDC, management prioritizes the treatment of the invasive component. High-grade EPC often requires systemic therapies due to its poorer prognosis and increased risk of lymph node involvement.

Updates in the Use of Immunohistochemical Stains in Breast and Gynecologic Pathology

CONTEXT.—

The use of immunohistochemical stains in breast and gynecologic pathology has become increasingly complex, with various diagnostic, prognostic, and predictive applications.

OBJECTIVE.—

To provide an update and review of immunohistochemical stains used in the practice of breast and gynecologic pathology. Established and new entities are reviewed, with descriptions of histomorphology and immunohistochemical staining patterns and discussion of interpretive pitfalls.

DATA SOURCES.—

Data were obtained from review of the English-language literature and firsthand experience of the authors in breast and gynecologic pathology.

CONCLUSIONS.—

Many entities in breast and gynecologic pathology benefit from evaluation with various immunohistochemical stains. These studies not only aid in the diagnosis and staging of tumors but also can provide prognostic and predictive information. Updated guidelines for recommended ancillary studies such as mismatch repair, p53, and human epidermal growth factor receptor 2 (HER2) studies in endometrium, as well as estrogen and progesterone receptors and HER2 in breast, are discussed. Finally, the use and interpretation of established and novel immunohistochemical stains are discussed in various breast and gynecologic malignancies.