Whole-Genome Sequencing Analysis of Male Breast Cancer Unveils Novel Structural Events and Potential Therapeutic Targets.

The molecular characterization of male breast cancer (MaBC) has received limited attention in research, mostly because of its low incidence rate, accounting for only 0.5% to 1% of all reported cases of breast cancer each year. Managing MaBC presents significant challenges, with most treatment protocols being adapted from those developed for female breast cancer. Utilizing whole-genome sequencing (WGS) and state-of-the-art analyses, the genomic features of 10 MaBC cases (n = 10) were delineated and correlated with clinical and histopathologic characteristics. Using fluorescence in situ hybridization, an additional cohort of 18 patients was interrogated to supplement WGS findings. The genomic landscape of MaBC uncovered significant genetic alterations that could influence diagnosis and treatment. We found common somatic mutations in key driver genes, such as FAT1, GATA3, SMARCA4, and ARID2. Our study also mapped out structural variants that impact cancer-associated genes, such as ARID1A, ESR1, GATA3, NTRK1, and NF1. Using a WGS-based classifier, homologous recombination deficiency (HRD) was identified in 2 cases, both presenting with deleterious variants in BRCA2. Noteworthy was the observation of FGFR1 amplification in 21% of cases. Altogether, we identified at least 1 potential therapeutic target in 8 of the 10 cases, including high tumor mutational burden, FGFR1 amplification, and HRD. Our study is the first WGS characterization of MaBC, which uncovered potentially relevant variants, including structural events in cancer genes, HRD signatures, and germline pathogenic mutations. Our results demonstrate unique genetic markers and potential treatment targets in MaBC, thereby underlining the necessity of tailoring treatment strategies for this understudied patient population. These WGS-based findings add to the growing knowledge of MaBC genomics and highlight the need to expand research on this type of cancer.

Immunohistochemical analysis of IDH2 R172 hotspot mutations in breast papillary neoplasms: applications in the diagnosis of tall cell carcinoma with reverse polarity.

Tall cell carcinoma with reverse polarity is a rare subtype of breast carcinoma with solid and papillary growth and nuclear features reminiscent of those of the tall cell variant of papillary thyroid carcinoma. These tumors harbor recurrent IDH2 R172 hotspot mutations or TET2 mutations, co-occurring with mutations in PI3K pathway genes. Diagnosis of tall cell carcinomas with reverse polarity is challenging in view of their rarity and the range of differential diagnosis. We sought to determine the sensitivity and specificity of IDH2 R172 immunohistochemistry for the detection of IDH2 R172 hotspot mutations in this entity. We evaluated 14 tall cell carcinomas with reverse polarity (ten excision and five core needle biopsy specimens), 13 intraductal papillomas, 16 solid papillary carcinomas, and 5 encapsulated papillary carcinomas by Sanger sequencing of the IDH2 R172 hotspot locus and of exons 9 and 20 of PIK3CA, and by immunohistochemistry using monoclonal antibodies (11C8B1) to the IDH2 R172S mutation. The 14 tall cell carcinomas with reverse polarity studied harbored IDH2 R172 hotspot mutations, which co-occurred with PIK3CA hotspot mutations in 50% of cases. None of the other papillary neoplasms analyzed displayed IDH2 R172 mutations, however PIK3CA hotspot mutations were detected in 54% of intraductal papillomas, 6% of solid papillary carcinomas, and 20% of encapsulated papillary carcinomas tested. Immunohistochemical analysis with anti-IDH2 R172S antibodies (11C8B1) detected IDH2 R172 mutated protein in 93% (14/15) of tall cell carcinomas with reverse polarity samples including excision (n = 9/10) and core needle biopsy specimens (n = 5), whereas the remaining papillary neoplasms (n = 34) were negative. Our findings demonstrate that immunohistochemical analysis of IDH2 R172 is highly sensitive and specific for the detection of IDH2 R172 hotspot mutations, and likely suitable as a diagnostic tool in the evaluation of excision and core needle biopsy material of tall cell carcinomas with reverse polarity.

Metastatic Breast Carcinoma in Cerebrospinal Fluid: A Cytopathological Review of 15 Cases.

The incidence of metastatic carcinoma to the meninges ("meningeal carcinomatosis" [MC]) is increasing due to longer survival of patients and improved imaging techniques. Currently, MC is best diagnosed by cytopathological evaluation of cerebrospinal fluid (CSF). Breast primaries are the commonest cause of MC; although cytopathological features thereof have not been, as yet, fully characterized. In this study of meningeal mammary carcinomatosis, relevant clinicopathological data and archived cytopathological preparations of all "suspicious" and "positive" CSF specimens (1992-2015), from patients with a history of breast carcinoma, were retrieved and reviewed. Twenty-three "positive" CSF specimens, derived from 15 patients formed the basis of this study. All specimens were processed as Cytospin preparations, and stained by Papanicolaou and Diff-Quik techniques. All patients were female, with a mean age of 57 (range: 32-85) years. Mean interval between initial diagnosis of breast carcinoma and "positive" CSF was 32 (range 6-84) months. All 23 specimens (100%) were "cellular" (>10 carcinoma cells). Eighteen (78%) specimens showed only isolated nonclustered cells, and 5 (22%) specimens showed both cell clusters and isolated cells. In most "positive" cases, metastatic breast carcinoma cells showed variation in cell size, with hyperchromatic nuclei, irregular nuclear membranes, prominent nucleoli and cytoplasmic vacuolization. The background in some CSF samples showed red blood cells and fibrin admixed with rare lymphocytes and histiocytes. One specimen showed necrotic debris. Papanicolaou and Diff-Quik-stained Cytospin preparations were equally diagnostic, as the aforementioned findings were present in both types of preparation.

Squamous Cell Carcinoma In Situ of the Breast: Report of a Case.

We present the case of a 73-year-old woman with pure squamous cell carcinoma in situ of the left breast. This non-invasive malignancy exhibited pure squamous type of architectural and cytologic features without any evidence of glandular differentiation either in the initial needle core biopsy or in the subsequently performed excisional biopsy and simple mastectomy. The tumor spanned 1.6 cm, involved numerous ducts and terminal ducts and extended into lobules, and was characterized by keratinizing squamous cells with intermediate-grade nuclei. Intercellular bridges extended between the malignant squamous cells. Keratinous debris with "pearl" formation was evident in most involved glands. No invasive carcinoma was identified. There was no evidence of metastatic disease in the ipsilateral sentinel lymph nodes. Thus far, only three cases of squamous cell carcinoma in situ of the breast have been reported in one series-none of which showed any evidence of recurrent or metastatic disease at last follow-up. In our case, treated exclusively by surgery, there was no evidence of disease 11 years after diagnosis.

Complexities and challenges in the pathologic assessment of size (T) of invasive breast carcinoma.

Size (the "T" in the TNM System) of invasive breast carcinoma is a proven independent prognostic factor; however, its accurate determination can be challenging. The purpose of this review is to discuss the complexities inherent in determining "T"-including those encountered in the clinical measurement ("cT", ie, physical and radiologic assessment) as well as pathologic determination (pT) of invasive breast carcinomas. Pathologic estimation of tumor size, macroscopic, as well as microscopic, can be problematic due to the complexity of multiple situations, seeming confusion regarding staging guidelines, and interobserver variation in interpretation. Additional problematic scenarios in determination of "T" include those incurred in excisions performed after the performance of needle core biopsies, and in cases wherein there are multiple foci of invasive carcinoma, as well as in carcinomas status post-neoadjuvant chemotherapy. It can also be difficult to determine "T" in certain types of invasive carcinoma, particularly those of the lobular type. In this communication, some of the complexities and challenges in determing "T" are discussed, and modest suggestions are offered to assist in optimizing such assessments.

Pathological evaluation of nipple-sparing mastectomies with emphasis on occult nipple involvement: the Weill-Cornell experience with 325 cases.

Nipple-sparing mastectomy (NSM) is an increasingly utilized surgical option in managing breast carcinoma; however, data on malignant involvement of a separately submitted nipple margin are scant. Consecutive NSM, including those performed for therapeutic and prophylactic purposes, over a 4-year period (2007-2011), were studied. A separately submitted nipple margin was evaluated by permanent H&E preparations and via frozen section evaluation whenever requested. 325 consecutive NSM specimens, 208 (64%) therapeutic-NSM, and 117 (36%) prophylactic-NSM were studied. All nipples were clinically unremarkable. 86% (179/208) of nipple margins from therapeutic-NSM and 100% (117/117) from prophylactic-NSM showed no histopathologic abnormality. 14% (29/208) of nipple margins from therapeutic-NSM and no nipple margin from prophylactic-NSM showed malignancy. Frozen section evaluation was performed in 188/325 NSM (58%) with a sensitivity of 64% and specificity of 99%. Central tumor location and stage N2/N3 lymph node status were significantly associated with nipple margin positivity (χ(2) ≤ 0.05). Subsequent nipple resection was performed in 69% (20/29) of nipple margin-positive cases with residual malignancy found in 40% (8/20, including three cases of invasive carcinoma). In a mean follow-up of 33 months, one invasive carcinoma recurred in the "saved" nipple, 36 months after therapeutic-NSM. 14% (29/208) of nipple margins in therapeutic-NSM and no nipple margin (0/117) in prophylactic-NSM showed malignancy. Central tumor location and N2/N3 stage were significantly associated with nipple margin positivity (χ(2) ≤ 0.05).

Papillary Breast Tumors: Continuing Controversies and Commentary on WHO's 2019 Criteria and Classification.

The category of papillary breast tumors includes a limited number of entities. Nonetheless, this relatively uncommon group of tumors seems to instigate a disproportionate degree of diagnostic disquiet. As a group, papillary breast tumors suffer from a relatively high rate of discordant interpretation. The latter is due to the inherent complexity of the lesions compounded by conflicting criteria as well as simmering controversies. For instance, "encapsulated" papillary carcinoma remains contentious with regards to whether these are noninvasive or not, and the assessment of the extent of the invasive versus noninvasive components in many solid papillary carcinomas can be problematic. The latest classification system of breast tumors enunciated by the World Health Organization (WHO), that is, Breast Tumors, which appeared in 2019, mainly sought to incorporate advances in basic and clinical sciences into diagnostic criteria for the entire spectrum of breast neoplasms-including papillary ones. The latter category of tumors is discussed at some length in Breast Tumors; however, it still appears to suffer from some lack of clarity in its subclassification. It is our intent in this communication to provide an overview of the controversies around papillary breast tumors, and offer comments on its coverage in Breast Tumors-so that any tangible or perceived ambiguities therein could be addressed in its next edition.

Whole-exome sequencing analysis of juvenile papillomatosis and coexisting breast carcinoma.

Juvenile papillomatosis (JP) of the breast is a rare benign mass-forming lesion occurring in young women, which is histologically characterized by a constellation of proliferative changes and large cysts, giving it the gross appearance of Swiss cheese. A subset of patients with JP report a family history of breast carcinoma and/or coexisting or subsequent breast carcinoma. We performed whole-exome sequencing of the hyperplastic epithelial component of three JPs, including one with coexisting ductal carcinoma in situ (DCIS) and invasive ductal carcinoma of no special type (IDC-NST). JPs harbored clonal somatic PIK3CA hotspot mutations in two cases. In the JP with coexisting DCIS and IDC-NST, these lesions were clonally related to the associated JP, sharing a clonal PIK3CA E542K somatic hotspot mutation. JP showed a paucity of copy number alterations, whereas the associated DCIS and IDC-NST showed concurrent 1q gains/16q losses, hallmarks of estrogen receptor (ER)-positive breast cancers. We observed JP to harbor a dominant aging-related mutational signature, whereas coexisting DCIS and IDC-NST showed greater exposure to an APOBEC signature. Taken together, our findings suggest that, at least in a subset of cases, JP might constitute the substrate from which DCIS and invasive breast carcinomas develop.

Investigation of triple-negative breast cancer risk alleles in an International African-enriched cohort.

Large-scale efforts to identify breast cancer (BC) risk alleles have historically taken place among women of European ancestry. Recently, there are new efforts to verify if these alleles increase risk in African American (AA) women as well. We investigated the effect of previously reported AA breast cancer and triple-negative breast cancer (TNBC) risk alleles in our African-enriched International Center for the Study of Breast Cancer Subtypes (ICSBCS) cohort. Using case-control, case-series and race-nested approaches, we report that the Duffy-null allele (rs2814778) is associated with TNBC risk (OR = 3.814, p = 0.001), specifically among AA individuals, after adjusting for self-indicated race and west African ancestry (OR = 3.368, p = 0.007). We have also validated the protective effect of the minor allele of the ANKLE1 missense variant rs2363956 among AA for TNBC (OR = 0.420, p = 0.005). Our results suggest that an ancestry-specific Duffy-null allele and differential prevalence of a polymorphic gene variant of ANKLE1 may play a role in TNBC breast cancer outcomes. These findings present opportunities for therapeutic potential and future studies to address race-specific differences in TNBC risk and disease outcome.

Papillary Lesions of the Male Breast: A Study of 117 Cases and Brief Review of the Literature Demonstrate a Broad Clinicopathologic Spectrum.

Papillary lesions of the male breast (PLMB) are uncommon. To date, PLMB have been reported as individual case reports and in relatively small series. We reviewed cases of PLMB diagnosed at our medical center over a 19-year (2000-2019) period. A total of 117 cases were identified, with an age range of 7 months to 88 years. These cases included 3 of papillary ductal hyperplasia, 5 intraductal papillomas, 1 adenomyoepithelioma, 5 atypical papillomas (ie, papillomas with atypia), 51 papillary ductal carcinoma in situ, 14 encapsulated papillary carcinomas, 38 solid papillary carcinomas, and 8 invasive papillary carcinomas. Malignant papillary neoplasms, including invasive and noninvasive ones, had a mean size of 1.3 cm (range: 0.3 to 4.4 cm), and all were ER and HER2. Fifty-four percent (19/35) of carcinomas were treated with excision alone, 46% (16/35) underwent mastectomy, and 63% (22/35) had axillary lymph node sampling. Only one case had metastatic involvement of axillary lymph nodes. Of the cases with follow-up, no (0/8) invasive carcinoma showed distant metastasis or proved fatal, and no (0/23) noninvasive papillary carcinoma recurred. Two notable cases of PLMB were encountered: one of a 7-month-old boy with NF1 mutation and florid papillary hyperplasia, and another of a 57-year-old man with Klippel-Feil syndrome and bilateral solid papillary carcinoma, invasive and oligometastatic on one side and noninvasive on the other. On the basis of this study of PLMB cases, the largest to date, and review of literature, we conclude that PLMB span a broad clinicopathologic spectrum, and that both invasive and noninvasive papillary carcinomas have relatively good prognosis.

Apocrine Variant of Pleomorphic Lobular Carcinoma In Situ: Further Clinical, Histopathologic, Immunohistochemical, and Molecular Characterization of an Emerging Entity.

To date, the apocrine variant of lobular carcinoma in situ (AP-LCIS) has been cursorily described as a subtype of lobular carcinoma in situ (LCIS). We retrospectively reviewed 34 cases of AP-LCIS (including 23 associated with invasive lobular carcinoma) to fully characterize it. AP-LCIS typically presented with screen-detected calcifications in older women (mean age: 65 y) and was characterized by distended terminal duct lobular units with relatively large "pleomorphic" cells, central necrosis, and calcifications. AP-LCIS cells exhibited abundant eosinophilic occasionally granular cytoplasm, hyperchromatic nuclei, and prominent nucleoli. Synchronous classic and/or florid LCIS was identified in 24/34 (70%) AP-LCIS, and in 9/11 (82%) pure AP-LCIS. Most (68%) cases of AP-LCIS were estrogen receptor-positive (50% strongly), 35% were progesterone receptor-positive, 26% were human epidermal growth factor 2-positive, 18% demonstrated high-proliferation rate (Ki67: >15%), and 90% were androgen receptor-positive. Aurora kinase A, immunoreactive in 38% of AP-LCIS cases, was not significantly associated with recurrence, development of invasion, or nodal positivity (P>0.05). Compared with conventional (nonapocrine) pleomorphic lobular carcinoma in situ (P-LCIS), aurora kinase A was expressed in a significantly greater proportion of P-LCIS (100%). AP-LCIS and P-LCIS did not otherwise differ in clinicopathologic features. Next-generation sequencing utilizing the Oncomine Comprehensive Panel v2, performed on 27 AP-LCIS cases, showed no specific molecular findings. In a mean follow-up of 57 months, 2 (of 11, 18%) pure AP-LCIS cases recurred (2 both in situ and invasive) and none metastasized or proved fatal. AP-LCIS should be regarded as another high-grade LCIS similar to P-LCIS in many respects, and pending additional studies should be managed similarly.