Mesenchymal breast lesions

Demystifying Breast Disease Markers

Breast imaging radiologists regularly perform image-guided biopsies of suspicious breast lesions based on features that are associated with a likelihood of malignancy ranging from 2% to greater than 95% (Breast Imaging Reporting and Data System categories 4 and 5). As diagnostic partners, pathologists perform histopathologic assessment of these tissue samples to confirm a diagnosis. Correlating the imaging findings with the histopathologic results is an integral aspect of multidisciplinary breast care. Assessment of radiologic-pathologic concordance is vital in guiding appropriate management, as it enables identification of discordant results, minimizing the chance of misdiagnosis. Undersampling can lead to false-negative results, with the frequencies of false-negative diagnoses varying on the basis of multiple factors, including biopsy type (eg, core needle, vacuum-assisted needle), needle gauge, and type of lesion sampled at biopsy (ie, mass, calcifications, asymmetry, architectural distortion). Improving a radiologist's knowledge of macroscopic and microscopic breast anatomy and more common breast diseases and their expected imaging findings ensures more accurate radiologic-pathologic correlation and management recommendations. The histopathologic and molecular characteristics of biopsy-sampled breast lesions aid in making an accurate diagnosis. Hematoxylin-eosin staining provides critical morphologic details, whereas immunohistochemical staining enables molecular characterization of many benign and malignant lesions, which is critical for tailored treatment. The authors review commonly encountered benign and malignant breast diseases, their corresponding histopathologic phenotypes, and the histopathologic markers that are essential to clinching the diagnosis of these entities. As part of a multidisciplinary team that provides optimal patient care, radiologists should be knowledgeable of the foundations of histopathologic diagnosis and the implications for patient management to ensure appropriate radiologic-pathologic concordance. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Epithelioid myofibroblastoma with concurrent presentation of LCIS and DCIS

Myofibroblastoma (MFB) of the breast is a rare benign neoplasm of the mammary stroma. Several morphologic variants have been described in the literature, which can create diagnostic challenges for pathologists, in particular the epithelioid variant of MFB, which can mimic invasive lobular carcinoma. We report a case of a 72-year-old female who presented for a painless breast lump and was later found to have 2 lesions on imaging, with 1 lesion corresponding to the palpable lump and the other lying in a different quadrant. Core-needle biopsies demonstrated ductal carcinoma in-situ at both lesional sites with what was originally felt to be an invasive lobular carcinoma at the lesional site which did not correspond to the palpable lump. After mastectomy, with more complete visualization microscopically of the lesional area originally felt to be an invasive lobular carcinoma, the final pathology was consistent with a MFB, predominantly epithelioid variant, in addition to ductal carcinoma in-situ and lobular carcinoma in-situ. In this paper we describe the imaging findings of an epithelioid MFB and how its nonspecific nature necessitates close communication between the radiologist and pathologist to make the correct diagnosis.

Mesenchymal Tumors of the Breast: Fibroblastic/Myofibroblastic Lesions and Other Lesions

Mesenchymal breast tumors are a rare and diverse group of tumors that present some of the most challenging cases for multidisciplinary breast cancer teams. As a result of overlapping morphologies and a lack of large-scale studies on these tumors, practices are often heterogeneous and slow to evolve. Herein, we present a non-systematic review that focuses on progress, or lack thereof, in the field of mesenchymal breast tumors. We focus on tumors originating from fibroblastic/myofibroblastic cells and tumors originating from less common cellular origins (smooth muscle, neural tissue, adipose tissue, vascular tissue, etc.).

Mammary myofibroblastoma: Presentation of case

INTRODUCTION AND IMPORTANCE

Mammary myofibroblastoma (MFB) is a rare benign mesenchymal lesion. It belongs to the family of benign spindle cell tumours of the mammary stroma and may exhibit confusing variants. Some of them may mimic invasive tumours, leading to the diagnostic dilemmas, especially in core needle biopsy specimens or frozen sections. Familiarity with the characteristics of this tumour is of great importance for accurate diagnosis and proper treatment.

CASE PRESENTATION

We report about a rare form of CD34-negative mixed epithelioid/lipomatous form of mammary myofibroblastoma in a 48-year-old Caucasian premenopausal woman with no previous medical history. Breast imaging suggested a benign lesion. The core needle biopsy suggested breast MFB. The definitive diagnosis was established through histopathology and immunohistochemistry of the lumpectomy specimen.

CLINICAL DISCUSSION

Despite its rarity, breast MFB is a disease with a wide spectrum of histologic morphologies. CD34 positivity is seen in majority of MFB cases. MFBs uncommonly show absent expression of CD34, a potential diagnostic pitfall, just like in our case.

CONCLUSION

Pathologists should recognise the wide range of differential diagnoses and be familiar with the diverse morphological appearances of these lesions to make an accurate diagnosis. Surgical excision is at present the ordinary treatment of MFB.

Low to Intermediate (Borderline) Grade Breast Spindle Cell Lesions on Needle Biopsy: Diagnostic Approach and Clinical Management

Spindle cell proliferations of the breast are a heterogeneous group of lesions ranging from benign or reactive lesions to aggressive malignant neoplasms. Diagnosis on core biopsy can be particularly challenging as lesions displaying different lineages associated with variable outcomes share overlapping morphologies (scar vs. fibromatosis-like metaplastic carcinoma) whereas individual entities can exhibit a large variety of appearances (myofibroblastoma). In this review, lesions are grouped into lineage, when possible, including those showing fibroblastic/myofibroblastic differentiation, ranging from entities that require no additional management, such as scar and nodular fasciitis, to those with unpredictable clinical outcomes such as fibromatosis and solitary fibrous tumor or locally aggressive behavior such as dermatofibrosarcoma protuberans. The review of low-grade vascular lesions includes atypical vascular lesion and low-grade angiosarcoma. Also discussed are various adipocytic lesions ranging from lipoma to liposarcoma, and rare smooth muscle and neural entities more commonly encountered in locations outside the breast, such as leiomyoma, neurofibroma, schwannoma, or granular cell tumor. Optimal histological evaluation of these entities merges clinical and radiologic data with morphology and ancillary testing. We present our approach to immunohistochemical and other ancillary testing and highlight issues in pathology correlation with imaging. Recent updates in the management of breast spindle cell lesions are addressed. In a well-sampled lesion with radiographic concordance, the core biopsy diagnosis reliably guides management and we advocate the inclusion of management recommendations in the pathology report. Precise characterization using up to date guidelines is important to identify a subset of patients who may safely avoid unnecessary surgical procedures. A multidisciplinary approach with close collaboration with our clinical colleagues is emphasized.

Radiotherapy of Breast Cancer—Professional Guideline 1st Central-Eastern European Professional Consensus Statement on Breast Cancer

The international radiotherapy (RT) expert panel has revised and updated the RT guidelines that were accepted in 2020 at the 4th Hungarian Breast Cancer Consensus Conference, based on new scientific evidence. Radiotherapy after breast-conserving surgery (BCS) is indicated in ductal carcinoma in situ (stage 0), as RT decreases the risk of local recurrence (LR) by 50–60%. In early stage (stage I-II) invasive breast cancer RT remains a standard treatment following BCS. However, in elderly (≥70 years) patients with stage I, hormone receptor-positive tumour, hormonal therapy without RT can be considered. Hypofractionated whole breast irradiation (WBI) and for selected cases accelerated partial breast irradiation are validated treatment alternatives to conventional WBI administered for 5 weeks. Following mastectomy, RT significantly decreases the risk of LR and improves overall survival of patients who have 1 to 3 or ≥4 positive axillary lymph nodes. In selected cases of patients with 1 to 2 positive sentinel lymph nodes axillary dissection can be substituted with axillary RT. After neoadjuvant systemic treatment (NST) followed by BCS, WBI is mandatory, while after NST followed by mastectomy, locoregional RT should be given in cases of initial stage III–IV and ypN1 axillary status.

Myofibroblastoma of the breast: two case reports and literature review

Myofibroblastoma (MFB) is a relatively rare tumor of the breast parenchyma, which belongs to the family of the 'benign stromal tumor of the breast'. Two cases of MFB of the breast are described. Radiological imaging is nonspecific in MFB, and pathological examination of needle biopsy or surgically resected specimen is necessary for the diagnosis. Surgery is recommended and considered curative without additional treatment; however, patients should be followed-up.

Myofibroblastoma of the breast in postmenopausal women: Two case reports with imaging findings and review of the literature

Myofibroblastoma is a rare benign mesenchymal tumor of the breast, which tends to affect postmenopausal women and older men. It usually presents as a unilateral, well-circumscribed, firm, nontender, and freely mobile mass. We report two cases of myofibroblastoma in postmenopausal women with the imaging findings of mammography, ultrasonography, computed tomography, ¹⁸ F-Fluorodeoxyglucose-positron emission tomography computed tomography, and pathologic findings and review the relevant literature.

Breast Lesions in Women Aged Younger than 30 Years: Clinical Presentation, Diagnosis, and Management

Women aged younger than 30 years frequently present with palpable breast lesions, breast pain, and nipple discharge. Diagnostic work-up often results in benign findings, including a variety of benign solid masses, infectious or inflammatory conditions, pregnancy- or lactation-related abnormalities, and normal variants. While rare, breast cancer can occur within this demographic, and it is often more advanced and aggressive than in older women. Other rare tumors can present within this patient demographic, including primary sarcoma of the breast and granular cell tumors. A knowledge of the clinical presentation, diagnostic approach, and management of this spectrum of pathologic entities is crucial to ensure optimal and cost-effective care within this patient demographic.

First report of canine mammary gland granular cell tumour: case description and review of the literature

The case of a 5-year-old intact female Pitbull Terrier with a granular cell tumour (GCT) of the mammary gland is presented. The dog was admitted for surgical removal of a non-painful lump assumed to be a fibroadenoma. Histological and immunohistochemical findings leading to the diagnosis consisted of polygonal tumour cells with well-defined cell borders and granular cytoplasm, staining positively with neuron-specific enolase (NSE) and protein S100 and negatively for cytokeratin AE1-AE3. Some important points in the diagnostic and therapeutic approach to this uncommon neoplasm are discussed. To our best knowledge this is the first case of such tumour in the mammary gland described in the veterinary literature.

Spindle Cell Lesions of the Breast on Fine-Needle Aspiration Biopsy: A Miscellany of Masses

A variety of primary breast and metastatic lesions to the breast can present with spindle cell cytomorphology. These lesions may range from benign reactive or inflammatory lesions to high-grade malignancies. Spindle cell lesions of the breast are not often seen on fine-needle aspiration biopsy (FNAB) but need to be correctly managed when they are encountered. While mesenchymal lesions of the breast have a spindle morphology, lesions derived from the epithelium and myoepithelium can be spindled as well. By assessing if the lesion comprises spindle cells only or if other components such as epithelial cells are apparent and then determining whether the spindle cells appear bland or pleomorphic, together with close clinicoradiologic correlation and prudent use of ancillary tests, a variety of lesions can be diagnosed on FNAB. However, core needle biopsy or excision biopsy may be required in some patients. The cytomorphology, ancillary studies, and clinicoradiologic findings of a range of spindle cell lesions of the breast are further discussed.

Mesenchymal Lesions of the Breast: What Radiologists Need to Know

OBJECTIVE

Mesenchymal breast tumors originate from the various components of mammary stroma. The aim of this review is to discuss the clinical presentation, imaging appearance, and management of mesenchymal breast lesions.

CONCLUSION

Although many mesenchymal tumors exhibit characteristic findings on imaging, others show nonspecific characteristics and require tissue biopsy for diagnosis. An awareness of the clinical and imaging presentation is essential in guiding the differential diagnosis and patient management.

Radiologic presentation of a myofibroblastoma of the adult male breast

We present the case of a 50-year-old male with bilateral gynecomastia who was incidentally found to have 0.8-cm subareolar mass on computed tomography. Mammographic and sonographic characteristics of the lesion are described as well as a brief historical review of myofibroblastoma, a rare mesenchymal tumor.

Core Biopsy of Vascular Neoplasms of the Breast: Pathologic Features, Imaging, and Clinical Findings

Vascular lesions (VLs) of the breast present a diagnostic challenge on breast core biopsy (BCBx). We report on 27 VLs presenting on BCBx. The mean patient age was 60 years, and mean size was 7.5 mm (range, 1.6 to 16 mm). Presentation included palpable mass in 6 (22%), incidental in 6 (22%), and an imaging abnormality in 15 (56%) cases. Imaging impression included hematoma (24%), lymph node (10%), fat necrosis (10%), tortuous vessel (5%), and not provided in 52%. The lesions were classified on the basis of BCBx or BCBx and excision (available in 16 pts) as follows: 1 low-grade angiosarcoma, 8 angiolipomas, 6 capillary hemangiomas, 4 cavernous hemangiomas, 2 hemangiomas (not otherwise specified), 1 papillary endothelial hyperplasia, and 5 perilobular hemangiomas. The angiosarcoma was 9 mm, detected incidentally by magnetic resonance imaging, and showed dissection of stromal collagen, infiltration of glands, high cellularity, moderate cytologic atypia, scant mitotic activity, and Ki-67 reactivity of 10%. Among the 26 benign VLs, worrisome histologic features were noted in 14 on BCBx, including anastomosing vascular channels in 9, moderate cytologic atypia in 4, high cellularity in 2, Ki-67>10% in 2, mitotic activity in 1, and infiltration of glands in 1. Of the 12 VLs without worrisome features, the lesion extended to edge of core in 8, precluding complete evaluation. BCBx of VLs presents diagnostic challenges due to overlapping clinicopathologic and radiologic features with low-grade angiosarcoma. If completeness of removal is documented on BCBx, and cytoarchitectural changes are not worrisome, follow-up could be considered rather than excision. However, only 4 of these cases fulfilled those criteria.

Step by step approach to rare breast lesions containing spindle cells

Differential diagnosis of spindle cell lesions of breast is challenging for certain reasons. The most important reason is the presence of cytological atypia and mitosis in all three conditions: reactive, benign, and malignant. Patients diagnosed with benign and malignant tumor/tumor-like lesions that had spindle cell components following the histopathological examination were included in the study. The patients’ medical records were accessed to obtain the clinical history, follow-up notes, and radiological findings. Following histopathological, immunohistochemical, and clinical evaluations, the patients were diagnosed as follows: pseudoangiomatous stromal hyperplasia (PASH), bilateral desmoid-type fibromatosis (FM), adenomyoepithelioma (AME), myofibroblastoma (MFB), malignant phyllodes tumor (MF), high-grade AS, post-chemotherapy osteosarcoma (OS) + Paget’s disease, and metaplastic carcinoma (MC). An algorithmic approach should be used in the diagnosis; cellular structure, presence and grade of atypia, growth pattern, mitotic activity, immunohistochemical staining, and clinical and radiological features should be evaluated together. Detection of some molecular changes can be useful in differential diagnosis.