Squamous metaplasia of lactiferous ducts (SMOLD)

Multimodality Imaging of Benign and Malignant Diseases of the Nipple-Areolar Complex

The nipple-areolar complex (NAC), a unique anatomic structure of the breast, encompasses the terminal intramammary ducts and skin appendages. Several benign and malignant diseases can arise within the NAC. As several conditions have overlapping symptoms and imaging findings, understanding the distinctive nipple anatomy, as well as the clinical and imaging features of each NAC disease process, is essential. A multimodality imaging approach is optimal in the presence or absence of clinical symptoms. The authors review the ductal anatomy and anomalies, including congenital abnormalities and nipple retraction. They then discuss the causes of nipple discharge and highlight best practices for the imaging workup of pathologic nipple discharge, a common condition that can pose a diagnostic challenge and may be the presenting symptom of breast cancer. The imaging modalities used to evaluate and differentiate benign conditions (eg, dermatologic conditions, epidermal inclusion cyst, mammary ductal ectasia, periductal mastitis, and nonpuerperal abscess), benign tumors (eg, papilloma, nipple adenoma, and syringomatous tumor of the nipple), and malignant conditions (eg, breast cancer and Paget disease of the breast) are reviewed. Breast MRI is the current preferred imaging modality used to evaluate for NAC involvement by breast cancer and select suitable candidates for nipple-sparing mastectomy. Different biopsy techniques (US -guided biopsy and stereotactic biopsy) for sampling NAC masses and calcifications are described. This multimodality imaging approach ensures an accurate diagnosis, enabling optimal clinical management and patient outcomes. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Nipple Lesions of the Breast: An Update on Morphologic Features, Immunohistochemical Findings and Differential Diagnosis

Because of the unique anatomic structure of the nipple, a few specific breast lesions occur only at this site. Large lactiferous sinuses may be involved by inflammatory conditions such as squamous metaplasia of lactiferous ducts and ductal ectasia or be the site of uncommon superficial epithelial neoplasms such as nipple adenoma or syringomatous tumor of the nipple. Paget disease of the nipple may be secondary to intraepidermal extension of ductal carcinoma in situ in the underlying lactiferous ducts or develop from malignant transformation of Toker cells. Invasive breast cancer may also arise primarily in the nipple. Most of these conditions present as a palpable mass and/or skin changes with or without nipple discharge. Due to the delicate location and often relatively small size of nipple lesions, biopsy specimens are often superficial and fragmented, and the interpretation is challenging. Knowledge of the morphologic and immunophenotypic features of nipple lesions is essential in making the correct diagnosis. Information on the molecular alterations underpinning nipple neoplasms is currently very limited.

Inflammatory Lesions of the Breast

CONTEXT.—

Inflammatory lesions of the breast are rare but not infrequently pose problems both clinically and morphologically, particularly on needle core biopsies. These lesions range from acute inflammatory conditions to chronic lymphoplasmacytic and lymphohistiocytic to granulomatous inflammatory diseases.

OBJECTIVE.—

To provide a comprehensive overview of inflammatory lesions of the breast, with etiopathogenesis and clinical, radiologic, and pathologic features as well as differential diagnostic considerations, clinical management, and prognosis.

DATA SOURCES.—

The existing literature in the English language, including original research articles and review articles describing inflammatory lesions of the breast.

CONCLUSIONS.—

Inflammatory lesions of the breast are characterized by a wide variety of clinical, radiologic, and morphologic features. The histopathologic differential diagnosis often includes a neoplastic process requiring ancillary studies and correlation with clinical and radiologic findings. Although most specimens display nonspecific findings precluding a definitive pathologic diagnosis, pathologists have a unique opportunity to play a crucial role in identifying key histologic features suggestive of certain entities, such as cystic neutrophilic granulomatous mastitis, immunoglobulin (Ig) G4 mastitis, or squamous metaplasia of lactiferous ducts, in the right clinical and radiologic context, and thereby guiding optimal and timely clinical management. The information presented herein will be helpful to practicing anatomic pathologists and pathology trainees in becoming more familiar with specific morphologic features and overcoming differential diagnostic challenges related to pathology reporting of inflammatory lesions of the breast.

Further Characterization of Clinicopathologic Features of Cystic Neutrophilic Granulomatous Mastitis

OBJECTIVES

Clinical and demographic features of cystic neutrophilic granulomatous mastitis (CNGM) have not been fully explored due to the rarity of the disease. Herein we studied clinicopathologic characteristics of CNGM in a sizable hospital-based cohort.

METHODS

A case-control study was performed to compare clinicopathologic characteristics between patients with CNGM and granulomatous mastitis other than CNGM and between CNGM with and without Corynebacterium identification.

RESULTS

Cases of CNGM (n = 31) and non-CNGM (n = 30) were included. Compared with the non-CNGM group, patients with CNGM were statistically significantly younger (median age: 38 vs 43 years), were less likely to be smokers (9% vs 40%), were more likely to have a painful lesion (97% vs 77%) or a larger mass-like lesion (median size: 4.6 vs 1.9 cm), and tended to have a higher Breast Imaging Reporting and Data System score in radiologic studies (score ≥4: 81% vs 53%), positive Corynebacterium identification results (36% vs 0%), and a longer resolving time (12 vs 6 months; all P values for above comparisons <.05). Among CNGM cases, patients with and without Corynebacterium identification shared a similar clinicopathologic profile.

CONCLUSIONS

Our study further demonstrated that CNGM is a unique infectious disease with distinct clinicopathologic features.

Treatments for Periductal Mastitis: Systematic Review and Meta-Analysis

Introduction

Periductal mastitis (PDM) is a complex benign breast disease with a prolonged course and a high risk of recurrence after treatment. There are many available treatments for PDM, but none is widely accepted. This study aims to evaluate the various treatment failure rates (TFR) of different invasive treatment measures by looking at recurrence and persistence after treatment. In this way, it sets out to inform better clinical decisions in the treatment of PDM.

Methods

We searched PubMed, Embase, and Cochrane Library databases for eligible studies about different treatment regimens provided to PDM patients that had been published before October 1, 2019. We included original studies written in English that reported the recurrence and/or persistence rates of each therapy. Outcomes were presented as pooled TFR and 95% CI for the TFR.

Results

We included 27 eligible studies involving 1,066 patients in this study. We summarized 4 groups and 10 subgroups of PDM treatments, according to the published studies. Patients treated minimally invasively (group 1) were subdivided into 3 subgroups and pooled TFR were calculated as follows: incision and drainage (n = 73; TFR = 75.6%; 95% CI 27.3-100%), incision alone (n = 74; TFR = 20.1%; 95% CI 0-59.9%), and breast duct irrigation (n = 123; TFR = 19.4%; 95% CI 0-65.0%). Patients treated with a minor excision (excision of the infected tissue and related duct; group 2) were divided into 4 subgroups and pooled TFR were calculated as follows: wound packing alone (n = 127; TFR = 2.1%; 95% CI 0-5.2%), primary closure alone (n = 66; TFR = 37.1%; 95% CI 9.5-64.8%), primary closure under antibiotic treatment cover (n = 55; TFR = 4.8%; 95% CI 0-11.4%), and additional nipple part removal (n = 232; TFR = 9.6%; 95% CI 5.8-13.4%). Patients treated with a major excision (excision of the infected tissue and the major duct; group 3) included the following 2 subgroups: patients treated with a circumareolar incision (n = 142; TFR = 7.5%; 95% CI 0.4-14.7%) and patients treated with a radial incision of the breast (n = 78; TFR = 0.6%; 95% CI 0-3.6%). Group 4 contained patients receiving different major plastic surgeries. The pooled TFR of this group (n = 86) was 3.4% (95% CI 0-7.5%).

Conclusion

Breast duct irrigation, which is the most minimally invasive of all of the treatment options, seemed to yield good outcomes and may be the first-line treatment for PDM patients. Minor excision methods, except for primary closure alone, might be enough for most PDM patients. Major excision, especially with radial incision, was a highly effective salvage therapy. The major plastic surgery technique was also acceptable as an alternative treatment for patients with large lesions and concerns about breast appearance. Incision and drainage and minor excision with primary closure alone should be avoided for PDM patients. Further research is still needed to better understand the etiology and pathogenesis of PDM and explore more effective treatments for this disease.

Complex Fibroadenoma with Pronounced Squamous Metaplasia: A Rare Case Report, Differential Diagnostic Considerations, and Associated Breast Cancer Risk

Squamous metaplasia of the breast is a rare and unusual finding. A number of benign and malignant differential entities exist when squamous cells are present in a breast lesion. Our patient was found to have pronounced squamous metaplasia and keratin cysts arising in a complex fibroadenoma. The rare nature of squamous metaplasia arising in such a lesion poses some diagnostic challenges, as squamous epithelium and squamous metaplasia in the breast may raise suspicion for malignancy. Herein we present a unique case and discussion of benign and malignant differential entities. We also retrospectively reviewed a series of complex fibroadenomas in our institution, including the demographic and histologic features, and more importantly the associated breast cancer risk.

Inflammatory breast disease: A pictorial essay with radiological-pathological correlation

Inflammatory conditions of the breast are an important group of diseases that can mimic breast carcinoma on clinical and radiological grounds. This pictorial essay presents the radiological and pathological features of some of these entities.

A Review of Inflammatory Processes of the Breast with a Focus on Diagnosis in Core Biopsy Samples

Inflammatory and reactive lesions of the breast are relatively uncommon among benign breast lesions and can be the source of an abnormality on imaging. Such lesions can simulate a malignant process, based on both clinical and radiographic findings, and core biopsy is often performed to rule out malignancy. Furthermore, some inflammatory processes can mimic carcinoma or other malignancy microscopically, and vice versa. Diagnostic difficulty may arise due to the small and fragmented sample of a core biopsy. This review will focus on the pertinent clinical, radiographic, and histopathologic features of the more commonly encountered inflammatory lesions of the breast that can be characterized in a core biopsy sample. These include fat necrosis, mammary duct ectasia, granulomatous lobular mastitis, diabetic mastopathy, and abscess. The microscopic differential diagnoses for these lesions when seen in a core biopsy sample will be discussed.

Clinical experience with aspiration of breast abscesses based on size and etiology at an academic medical center

PURPOSE

Our purpose was to review needle aspiration of breast abscesses and identify factors associated with treatment by aspiration alone versus aspiration with surgical incision and drainage (I/D).

METHODS

This Institutional Review Board-approved, retrospective review of the breast ultrasound database from 2008 to 2010 identified 40 patients (41 abscesses) who underwent aspiration, with or without I/D. Demographics, imaging, number of aspirations, and microbiology were reviewed.

RESULTS

Twenty-two abscesses underwent aspiration only, 16 > 3 cm, 6 ≤ 3 cm (mean 4.3 cm, range 0.9-10 cm). Known risk factors included lactational (11), 3 weeks post partum (1), pregnancy (1), recent biopsy/lumpectomy (5). Nineteen abscesses underwent aspiration and I/D, 15 > 3 cm, 4 ≤ 3 cm (mean 4.1 cm, range 2.2-7.5 cm). Known risk factors included lactational (4), recurrent subareolar abscess (4), diabetes (3), hydradenitis suppuritiva (1), nipple piercing (2), smoking (1), pregnancy (1), HIV (1), and lumpectomy (1). Identified reasons for I/D included lack of improvement/recurrence (12), fistula (3), and one electively after clinical improvement of a recurrent subareolar abscess.

CONCLUSIONS

Abscesses associated with pregnancy and lactation or breast biopsy are effectively managed with aspiration, even when large. Recurrence, chronicity, or fistula may require surgical intervention.