Rare Presentation of Papillary Carcinoma Within a Sentinel Lymph Node in a Patient With Ductal Carcinoma in Situ of the Breast: A Challenging but Useful Case Report Discussion Regarding Displacement or True Metastasis?

Papillary carcinoma of the breast is a rare histologic subtype of invasive breast cancer. In contrast, ductal carcinoma in situ (DCIS) is a noninvasive, nonobligate precursor to invasive mammary carcinoma, confined within the terminal duct lobular unit of the breast and surrounded by an intact myoepithelial cell layer at the stromal/epithelial interface. We present an unusual case in which a patient with only DCIS of the breast exhibited papillary carcinoma within a sentinel lymph node, leading to questions about the origin of the lymph node lesion-whether it represents a true metastasis or iatrogenic displacement during diagnostic procedures. This case underscores the diagnostic challenges and clinical implications associated with such rare presentations.

Evaluating Low HER2 Status in Invasive Breast Carcinoma via HER2 Immunohistochemistry, with HER2 FISH Correlation: A Cohort of 112 Patients.

Introduction: Recent trials demonstrated clinically significant benefits in HER2-nonamplified breast cancer with HER2-low expression using novel anti-HER2 antibody-drug conjugates. Thus, HER2-low breast cancer was proposed as a separate diagnostic entity. Herein, we reclassify HER2-negative cancers according to the new HER2-low category using a modified system and further investigate HER2-very-low expression. Methods: 114 HER2 immunohistochemistry (IHC)-negative invasive breast tumors were identified from the pathology database of Mayo Clinic, Jacksonville, FL, between January 2019 and August 2022. Two blinded breast pathologists (BP) independently rescored HER2 IHC slides at 200x and 400x magnification. Discordant cases between the two BPs were rescored together. The most recent 2018 ASCO/CAP HER2 scoring criteria were used. HER2 (0) was subdivided into HER2 (absent) and HER2 (very low). HER2 FISH testing was performed in all cases. Results: The cohort comprised of 38 (33.3%) HER2 (0) and 76 (66.7%) HER2 (1+) tumors. The first round of rescoring at 200x and 400x magnification resulted in 17 (14.9%) HER2 (absent), 31 (27.2%) HER2 (very low), and 64 (56.2%) HER2 (1+) and 2 (1.8%) HER2 (2+) tumors by BP1 and 20 (17.5%) HER2 (absent), 33 (28.9%) HER2 (very low), and 61 (53.5%) HER2 (1+) tumors by BP2. The combined final rescoring by BP1 and BP2 was as follows: 15 (13.2%) HER2 (absent), 35 (30.7%) HER2 (very low), 63 (55.3%) HER2 (1+), and 1 (0.9%) HER2 (2+) cases. A comparison of the first round of rescoring between two BPs showed substantial agreement with Cohen's kappa value of 0.67. Both comparisons of first rescoring by BP1 and by BP2 to combined final rescoring showed almost perfect agreement with Cohen's kappa value of 0.83.Follow-up FISH studies showed one amplified tumor. Conclusion: Our data support the need for finer granularity, classification, and understanding of HER2-low breast cancers. We also show that reproducibility between trained BP can be obtained, albeit with scoring at high power and low threshold for showing challenging interpretations.

ERBB2 Amplification and HER2 Expression in Salivary Duct Carcinoma: Evaluation of Scoring Guidelines and Potential for Expanded Anti-HER2 Therapy.

Salivary duct carcinoma (SDC) is aggressive with limited therapeutic options. A subset of SDC display human epidermal growth factor receptor 2 (HER2) protein overexpression by immunohistochemistry, and some show ERBB2 gene amplification. Guidelines for HER2 scoring are not firmly established. Recent advances in breast carcinoma have established a role for anti-HER2 therapies in lesions with low HER2 expression lacking ERBB2 amplification. Delineating HER2 staining patterns in SDC is critical for evaluating anti-HER2 treatments. In total, 53 cases of SDC resected at our institution between 2004 and 2020 were identified. Androgen receptor (AR) and HER2 immunohistochemistry and ERBB2 fluorescence in situ hybridization were performed in all cases. AR expression was scored for percentage positive cells and categorized as positive (>10% of cells), low positive (1%-10%), or negative (<1%). HER2 staining levels and patterns were recorded, scored using 2018 ASCO/CAP guidelines, and categorized into HER2-positive (3+ or 2+ with ERBB2 amplification), HER2-low (1+ or 2+ without ERBB2 amplification), HER2-very low (faint staining in <10% of cells), or HER2-absent types. Clinical parameters and vital status were recorded. Median age was 70 years, with a male predominance. ERBB2-amplified tumors (11/53; 20.8%) presented at lower pT stages (pTis/pT1/pT2; P = .005, Fisher exact test) and more frequently had perineural invasion (P = .007, Fisher exact test) compared with ERBB2 nonamplified tumors; no other pathologic features differed significantly by gene amplification status. In addition, 2+ HER2 staining by 2018 ASCO/CAP criteria was most common (26/53; 49%); only 4 cases (8%) were HER2-absent status; 3+ HER2 staining was found in 9 tumors, and all were ERBB2 amplified. Six patients with HER2-expressing tumors received trastuzumab therapy, including 2 with ERBB2-amplified tumors. Overall survival and recurrence-free survival did not differ significantly based on ERBB2 status. This work suggests that 2018 ASCO/CAP guidelines for HER2 evaluation in breast carcinoma could be applied to SDC. Our findings also show broad overexpression of HER2 in SDC raising the possibility that more patients may benefit from anti-HER2-directed therapies.

HER2 IHC Expression and Gene Amplification in p53-aberrant High-grade Endometrial Endometrioid Carcinoma Suggests That This Population May Benefit From HER2 Testing and Targeted Therapy.

Among gynecologic cancers, uterine serous carcinoma (USC) has been shown to be human epidermal growth factor receptor 2 (HER2) amplified and trastuzumab has been included in the recent National Comprehensive Cancer Network (NCCN) guidelines for treatment of advanced stage or recurrent USC with HER2 overexpression/amplification. There is limited literature suggesting that a subset of high-grade endometrioid carcinomas with aberrant p53 expression may also be HER2 amplified and these patients could benefit from the addition of targeted therapy. We identified 59 p53-aberrant (mismatch repair proficient) FIGO 3 endometrioid carcinomas of the uterus. HER2 immunohistochemistry was performed in all 59 tumors and HER2 fluorescence in situ hybridization (FISH) was performed in 52 of the 59 cases. Four of the 59 cases were HER2 3+ by immunohistochemistry (6.7%), using the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2007, 2013, and 2018 criteria. HER2 FISH was performed in 3 of the 4 cases and was amplified in all 3. Nine, 8, and 7 tumors showed 2+ HER2 staining when applying 2018, 2013, and 2007 criteria, respectively, FISH was performed in 7 tumors and none were amplified. An additional 4 cases did not perfectly meet the 2018 ASCO/CAP criteria but were assigned a score of 2+, none were amplified by HER2 FISH. The remaining 42 cases showed 1+ or no staining for HER2, FISH was successfully performed in 38 tumors and none showed amplification. Approximately half of the tumors fulfilled criteria for HER2-low or HER2-very low (10 HER2-low and 20 HER2-very low). Our data shows that a subset of p53-aberrant high-grade endometrial endometrioid carcinoma express HER2 and these patients may benefit from the addition of targeted therapy. The role of targeted therapy in HER2-low gynecologic carcinoma is currently unexplored.

Encapsulated papillary carcinoma of the breast: A case report.

Breast malignancies diagnosed from screening mammography most commonly present as a new or enlarging lesion at the time of diagnosis. We present the unusual case of an encapsulated papillary carcinoma that demonstrated decreasing size on mammogram over several subsequent years. We review the unique imaging and histologic findings of papillary carcinoma that make this imaging conundrum possible.

Re-Classification with Outcome Correlation of Previously Diagnosed Malignant Phyllodes Tumors Applying the 2016 Consensus Guidelines.

Background. Classification of phyllodes tumors is challenging due unclear diagnostic criteria, recently addressed by consensus review criteria. Herein, we reviewed all malignant phyllodes tumor resections and reclassified them based on the consensus guidelines, correlating with outcome. We hypothesize that application of criteria would result in a significant proportion being "down-graded" to either borderline or benign phyllodes tumor. Methods. Primary resections of malignant phyllodes tumor were reviewed by four AP board-certified, breast fellowship-trained pathologists. Morphologic variables delineated in consensus guidelines (ie stromal cellularity, cellular atypia, tumor border, presence of heterologous elements, presence of stromal overgrowth) were evaluated. Following review, cases were reclassified as benign, borderline, or malignant. Results. Upon reclassification, 20% (5/20) cases were "down-graded" to borderline phyllodes tumor while 80% (15/20) remained malignant phyllodes tumor. Two morphologic features were statistically significant including broadly infiltrating tumor border in 80% (12/15) of malignant phyllodes tumors compared to none in borderline phyllodes tumor (0/5) (p = 0.004) and stromal overgrowth in 67% (10/15) of malignant phyllodes tumor compared to none in borderline phyllodes tumors (0/5) (p = 0.03). Upon review of the pathology reports, 30% (6/20) contained all 5 histomorphologic variables delineated in the consensus review criteria. Malignant phyllodes tumor resulted in five cases with recurrence (33.3%, 5/15) and three cases with metastases (20.0%, 3/15) and borderline phyllodes tumor resulted in one case with recurrence (20.0%, 1/5) and no metastases (0/5). Conclusion. The consensus guidelines for phyllodes tumor are useful for subclassification. We hypothesize that standardize reporting of the histomorphologic variables may lead to better consensus.

Locally advanced invasive lobular carcinoma presenting as skin erythema, with multimodality imaging correlation.

Invasive lobular carcinoma comprises 10-15% of invasive carcinomas of the breast. Its inconspicuous pattern of proliferation may lead to tumor manifestations that can be challenging to detect on mammography and clinical exam, which can result in tumor detection at advanced size and stage. This case demonstrates a locally advanced invasive lobular carcinoma and its subtle growth pattern illustrated on several imaging modalities, as well as its unique initial clinical presentation of skin erythema mistaken for rash.

A Collision Tumor in the Breast Consisting of Invasive Ductal Carcinoma and Malignant Melanoma.

Collision tumors are rare neoplasms that consist of at least two different cell lineages at the same site. Given the many possible combinations that can occur, collision tumors, while rare, have been reported in multiple locations such as the stomach, bladder, and thyroid. Collision tumors are rarely found in breast tissue, with only a few cases reported in the literature. We herein report a unique case of a 79-year-old woman with a history of melanoma who presented with a left breast mass that was subsequently found to have invasive ductal carcinoma (IDC) and metastatic melanoma in the breast tissue. This is one of the first reported combinations of these two malignancies.

Periductal Stromal Tumor of the Breast: One Institution's Review of 6 Tumors Over a 22 Year Period With Immunohistochemical Analysis.

Introduction. Periductal stromal tumor (PST) of the breast is a rare fibroepithelial neoplasm with controversial pathogenesis. Methods. A retrospective search of our Pathology database from 2000 to 2021 identified 6 PST, all evaluated according to the Armed Forces Institute of Pathology (AFIP) criteria. Immunohistochemistry for CD10, CD34, KIT, GATA3, p63, SOX10, ER, PR, HER2, smooth muscle actin (SMA), beta-catenin, and myogenin was performed as well. Results. All 6 patients were female and age ranged from 29 to 55 years (mean 40 years). Tumor size ranged from 2.9 to 5.9 cm (mean 3.0 cm). Data showed absence of leaf-like architecture (0/6), at least moderate hypercellularity (6/6), lack of a circumscribed border (5/6), coalescing nodules with intermixed adipose tissue (4/6), at least moderate stromal atypia (4/6), and an elevated mitotic activity ≥3mitotic figures/10 HPF (6/6). The stromal cells were positive for CD10 (4/4), CD34 (4/4), KIT (3/4), and SMA (3/4), and negative for GATA3 (0/6), p63 (0/6), SOX10 (0/6), ER (0/4), PR (0/4), HER2 (0/4), nuclear beta-catenin (0/5), and myogenin (0/4). No patient had a PST recurrence or metastasis (average follow-up of 91 months). Conclusion. We confirm that PST shares morphologic and immunophenotypic similarities with phyllodes tumor (PT). However, PST can be reliably differentiated from PT using the AFIP criteria. Additionally, PST's immunoprofile of positive KIT and CD34 stromal expression alongside the negative GATA3, p63, and SOX10 reactivity can aid the pathologist in excluding metaplastic carcinoma. All 6 of our PST behaved as benign neoplasms akin to benign PT.

Clinical and Pathologic Features Associated With Invasive Breast Carcinoma With 2018 American Society of Clinical Oncology/College of American Pathologists In Situ Hybridization Group 2 Results (Human Epidermal Growth Factor Receptor 2 [HER2]/Chromosome 17 Centromere [CEP17] Ratio ≥2.0 and Average HER2 Copy Number <4.0).

CONTEXT.­: The American Society of Clinical Oncology/College of American Pathologists updated the human epidermal growth factor receptor 2 (HER2) breast carcinoma testing guideline in 2018 to address issues from uncommon HER2 fluorescence in situ hybridization (FISH) results. Based on the 2013 American Society of Clinical Oncology/College of American Pathologists guideline, cases wherein the HER2/chromosome 17 centromere (CEP17) ratio of 2.0 or more with an average HER2 copy number of less than 4.0 were considered in situ hybridization (ISH) positive. Under the 2018 guideline, such cases are classified as ISH Group 2 and are no longer considered eligible for anti-HER2 therapy when the corresponding HER2 immunohistochemistry result is 0, 1+, or 2+. OBJECTIVE.­: To assess the clinical, pathologic, and treatment aspects of patients with ISH Group 2 results. DESIGN.­: We retrospectively reviewed HER2 FISH results at our center between January 2012 and December 2014 and identified and characterized cases with ISH Group 2 results. RESULTS.­: Thirty-nine cases with ISH Group 2 results from 39 patients were reviewed. Twenty of 39 (51%) patients received anti-HER2 therapy. Patients treated with HER2-targeted therapy were less likely to have hormone receptor-positive tumors, compared with patients without anti-HER2 treatment, though not significantly (P = .30). The only significant difference between the 2 patient groups was receipt of cytotoxic chemotherapy treatment (P < .001). Overall, clinical outcome was similar between the 2 groups (P > .99). CONCLUSIONS.­: This retrospective study with median follow-up of at least 6 years shows patients with ISH Group 2 tumors had similar clinical outcomes, irrespective of HER2-targeted therapy. Further analysis in the prospective setting would provide valuable data that would potentially inform clinical decision making.

A rare case of syringocystadenocarcinoma papilliferum of the breast: An institutional retrospective case review and brief literature review.

Syringocystadenocarcinoma papilliferum (SCACP) is a rare cutaneous adnexal tumor thought to originate from its benign counterpart, syringocystadenoma papilliferum. These tumors are predominantly located on the head and neck with their location on the breast extraordinarily reported; mammary localization poses a great diagnostic dilemma to the practicing pathologist. Herein, we report an unusual case of an 85-year-old woman with an outside diagnosis on a core needle biopsy of metaplastic mammary carcinoma. Upon consultative review of the partial mastectomy specimen, SCACP was identified. Herein, we review SCACP and the diagnostic challenge it poses, especially when localized to the breast. Furthermore, we perform a retrospective review of institutional pathology reports and identified four additional cases of SCACP diagnosed at our institution within the last decade. Finally, we briefly review the literature of SCACP. The entity of SCACP should be well known to pathologists to avoid misdiagnosis.

Amyloid in the breast: retrospective review with clinicopathological and radiological correlation of 32 cases from a single institution.

AIMS: Mammary amyloid is an uncommon and easily overlooked pathological diagnosis with ambivalent presentation. Herein, we delineate the clinicopathological and radiographic characteristics of mammary amyloid. METHODS AND RESULTS: The Department of Pathology database was searched from 1993 to 2019 for keywords 'breast' and 'amyloid', yielding 32 cases from 23 patients, including consultation cases. All patients were female, age range = 52-81 (mean = 67.4 years). The left breast was involved more than the right (43 versus 33%, respectively); bilateral amyloid involvement was also present (24%). Amyloid was most often associated with a benign histopathological diagnosis (57%), lymphoma in 39% [all B cell lymphomas; five of nine were mucosa-associated lymphoid tissue (MALT) lymphoma] and rarely with a concurrent epithelial malignancy (invasive lobular carcinoma, 4%). Of the 14 patients with available clinical history, amyloid presented as a mass clinically or radiographically (six patients, 43%), as microcalcifications (five patients, 36%), and only occasionally as an asymmetry (14%) or fibroglandular density (7%). Microscopic examination detected microcalcifications in an additional nine cases (total 14 patients; 44% of the cohort). Interestingly, one patient had concurrent epithelial and haematological malignancy and amyloid within an axillary lymph node. Co-morbidities included autoimmune diseases and multiple myeloma. CONCLUSION: The majority of mammary amyloid cases are associated with benign histopathological findings, while imaging most frequently noted microcalcifications or mass lesions. To avoid overlooking amyloid as simply fat necrosis or fibroelastotic stromal change, a low threshold for performing ancillary stains should be considered in elderly women with benign core needle findings performed for mass lesions or microcalcifications.

Rare Initial Manifestation of Lupus as Lobular Panniculitis of the Breast-A Case Report and Review of the Literature.

ABSTRACT: Lupus mastitis is a rare complication of systemic or discoid lupus erythematosus with an uncommon initial presentation when limited to the breast. In this article, we report a 42-year-old woman who presented with constant pain and tenderness in her breasts. Ultrasound imaging of the left breast revealed a 14-mm oval mass, suspicious for malignancy; a needle core biopsy was performed. Sections showed necrosis of the fat lobules with associated mixed nodular lymphoplasmacytic aggregates. Karyorrhectic debris, fibrinoid necrosis of small vessels, and microcalcifications were all present while the background breast parenchyma was unremarkable. The diagnosis of lupus mastitis was rendered. Subsequent serology showed negative dsDNA but positive antinuclear antibodies, C4, and anti -Sjögren';s-syndrome-related antigen A antibodies. Clinical features of active systemic disease were not identified at the patient's follow-up dermatology appointment 1 month after the biopsy, and she elected management for her nodules with steroids. To the best of our knowledge, only 40 other cases of lupus mastitis have been reported in the English literature, of which 25 presented as a mass and only in 6 lupus mastitis of the breast was the initial presentation. In conclusion, we bring much needed awareness to lupus mastitis as the first presentation of disease.

Benign Endocervical Polyp with Heterologous Elements in a 42-year-old Female: Report of a Case.

A 42-year-old female with unremarkable medical history presented for a routine cervical screening upon which an endocervical polyp was identified and submitted entirely for histopathologic evaluation. Microscopic examination showed multiple well-circumscribed nodular fragments of polyp with superficial erosion and focal acute inflammation. Benign endocervical glands were seen within a fibrotic stroma with a prominent smooth muscle component. Intermixed mature adipose tissue and large thick-walled vessels were also identified. Stromal and epithelial atypia were absent; similarly, stromal cellularity, mitoses, and condensation were not identified. Additional deeper levels did not reveal other heterologous elements. The diagnosis of a benign choristomatous endocervical polyp was rendered. As anticipated, the patient recovered completely. A review of the English literature demonstrates rare, namely two other reports of hamartomatous tissue in an endocervical polyp. To the best of our knowledge, we report the third such case.

Educational Case: Ductal Carcinoma In Situ (DCIS).

The following fictional case is intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, see http://journals.sagepub.com/doi/10.1177/2374289517715040.1.

A Comparison of Death Domain-Associated Protein 6 in Different Endometrial Carcinomas Histotypes.

BACKGROUND: Death domain-associated protein 6 (DAXX) is involved in regulating apoptosis via subcellular localization. The presence of DAXX point mutations correlates well with loss of nuclear expression on immunohistochemistry (IHC). In this study, we sought to determine (1) whether DAXX expression pattern is the same across different uterine carcinoma subtypes, and (2) which uterine carcinomas show loss of nuclear DAXX IHC. DESIGN: We studied 65 uterine carcinomas of the following histologic types: 30 endometrioid (12 FIGO [The International Federation of Gynecology and Obstetrics] grade 1, 12 FIGO grade 2, and 6 FIGO grade 3), 8 serous, 14 clear cell, and 13 undifferentiated/dedifferentiated type (UEC/DDEC). Nuclear DAXX IHC was assessed in each tumor and was graded semi-quantitatively as follows: 0% to 50%, 50% to 75%, and greater than 75% of lesional cells react. RESULTS: A total of 61% (25/41) of high-grade carcinomas (FIGO grade 3, serous, clear cell, and UEC/DDEC]) showed retained DAXX nuclear staining in >75% of lesional cells, compared with only 4.2% (1/24) of the low-grade carcinomas (FIGO grades 1 and 2) (P = .0001), where DAXX expression was cytoplasmic. In addition, in the 11 DDEC cases, all the differentiated components showed loss of nuclear DAXX compared with the undifferentiated components which retained nuclear DAXX expression. CONCLUSIONS: We demonstrate that loss of nuclear DAXX is present in low-grade endometrial carcinomas and the differentiated components in UEC/DDEC, but not in high-grade ones, suggesting DAXX's role in tumor progression and its potential as a therapeutic target in high-grade endometrial carcinomas.

Immediate Release of Gastrin-Releasing Peptide Mediates Delayed Radiation-Induced Pulmonary Fibrosis.

Radiation-induced pulmonary fibrosis (RTPF) is a progressive, serious condition in many subjects treated for thoracic malignancies or after accidental nuclear exposure. No biomarker exists for identifying the irradiated subjects most susceptible to pulmonary fibrosis (PF). Previously, we determined that gastrin-releasing peptide (GRP) was elevated within days after birth in newborns exposed to hyperoxia who later developed chronic lung disease. The goal of the current study was to test whether radiation (RT) exposure triggers GRP release in mice and whether this contributes to RTPF in vivo. We determined urine GRP levels and lung GRP immunostaining in mice 0 to 24 after post-thoracic RT (15 Gy). Urine GRP levels were significantly elevated between 24 hours post-RT; GRP-blocking monoclonal antibody 2A11, given minutes post-RT, abrogated urine GRP levels by 6 to 12 hours and also altered phosphoprotein signaling pathways at 24 hours post-RT. Strong extracellular GRP immunostaining was observed in lung at 6 hours post-RT. Mice given one dose of GRP monoclonal antibody 2A11 24 hours post-RT had significantly reduced myofibroblast accumulation and collagen deposition 15 weeks later, indicating protection against lung fibrosis. Therefore, elevation of urine GRP could be predictive of RTPF development. In addition, transient GRP blockade could mitigate PF in normal lung after therapeutic or accidental RT exposure.