HistopathologyPub Date : 2026-10-09DOI: 10.1111/his.70292
Ka Long Leung, Ronald C Chan, Conrad H Lee, Ngou-Men Wong, Monalyn Marabi, Shirley K Jamidi, Yun-Bi Ni, Julia Y Tsang, Man-Chi Eric Fu, Dajiang Guo, Gary M Tse
{"title":"Digital analysis of spatial expression of stromal fibroblast activation protein alpha (FAP) in DCIS.","authors":"Ka Long Leung, Ronald C Chan, Conrad H Lee, Ngou-Men Wong, Monalyn Marabi, Shirley K Jamidi, Yun-Bi Ni, Julia Y Tsang, Man-Chi Eric Fu, Dajiang Guo, Gary M Tse","doi":"10.1111/his.70292","DOIUrl":"https://doi.org/10.1111/his.70292","url":null,"abstract":"<p><strong>Introduction: </strong>The presence of non-progressing ductal carcinoma in situ (DCIS) cases has raised concerns of overtreatment, necessitating comprehensive risk prediction. The tumour microenvironment, especially cancer-associated fibroblasts (CAFs), plays a key role in DCIS progression. Fibroblast activation protein alpha (FAP), a CAF biomarker, has shown prognostic potential, but its clinical significance and spatial organization in DCIS remain rarely discussed.</p><p><strong>Methods: </strong>In this study, we employed a digital pathology pipeline to quantify stromal FAP expression and map its spatial organization. A total of 102 breast excision specimens were analysed, including pure DCIS and DCIS with co-existing invasive carcinoma (either nearby or distant). FAP expression was quantified and correlated with clinicopathological features and survival outcomes.</p><p><strong>Results: </strong>Our results showed that FAP expression was significantly higher in DCIS with nearby invasion compared to DCIS with distant invasion (P = 0.014) and pure DCIS (P = 0.006), reaching levels comparable to the invasive component itself. Within these high-FAP regions, no expression gradient from the invasive front was observed. In multivariable analysis, high FAP expression (P = 0.053) and nuclear grade (P = 0.043) were associated with invasion in older patients (≥50 years). Additionally, high FAP expression correlated with high nuclear grade (P = 0.008), papillary DCIS (P = 0.029) and HER2-enriched subtype (P = 0.0497). Although FAP was not an independent predictor of overall survival, it showed a trend towards poorer survival when combined with invasion.</p><p><strong>Conclusions: </strong>In conclusion, FAP is a promising biomarker for predicting nearby invasive carcinoma. Its integration into the existing risk stratification models could enhance clinically meaningful prediction.</p>","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":" ","pages":""},"PeriodicalIF":3.8,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149136401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HistopathologyPub Date : 2026-10-09DOI: 10.1111/his.70300
Costantino Ricci, Barbara Corti, Sara Coluccelli, Giulia Calafato, Debora Anconelli, Francesco Vasuri, Martina Lambertini, Federico Venturi, Biagio Scotti, Alessia Grillini, Eugenia Franchini, Thais Maloberti, Antonio De Leo, Giovanni Tallini, Elisa Gruppioni, Annalisa Altimari, Michelangelo Fiorentino, Gerardo Cazzato, Emi Dika, Dario de Biase
{"title":"Detection of NTRK1/2/3 rearrangements in pigmented spindle cell naevus of Reed: a comparative study of optimized pan-TRK immunohistochemistry, FISH and RNA-NGS.","authors":"Costantino Ricci, Barbara Corti, Sara Coluccelli, Giulia Calafato, Debora Anconelli, Francesco Vasuri, Martina Lambertini, Federico Venturi, Biagio Scotti, Alessia Grillini, Eugenia Franchini, Thais Maloberti, Antonio De Leo, Giovanni Tallini, Elisa Gruppioni, Annalisa Altimari, Michelangelo Fiorentino, Gerardo Cazzato, Emi Dika, Dario de Biase","doi":"10.1111/his.70300","DOIUrl":"https://doi.org/10.1111/his.70300","url":null,"abstract":"<p><strong>Aims: </strong>Pigmented spindle cell naevus of Reed (PSCN) is mainly characterized by MYO5A::NTRK3 fusion. However, the prevalence of NTRK fusions/rearrangements in PSCNs ranges from 15.8% to 57% in the literature, and the agreement among techniques for detecting these alterations has not been analysed. Here, we analysed NTRK fusions/rearrangements in a series of PSCNs using an optimized pan-TRK protocol, RNA-NGS fusion panel and FISH (NTRK1/2/3).</p><p><strong>Methods and results: </strong>Seventy-nine PSCNs were collected, reclassified (2025 WHO criteria and negative for BRAF V600E/RAS Q61R stains), and stained with a modified version of a recently proposed pan-TRK protocol (additional amplification steps and Red chromogen). In 64 and 57 cases with available material, we performed RNA-NGS and FISH (NTRK1/2/3) analyses, respectively. Pan-TRK was positive in 16 (20.3%) cases, all showing diffuse, granular, cytoplasmic staining of moderate intensity. In 59 cases with evaluable RNA-NGS data, 33 (55.9%) harboured MYO5A::NTRK3 fusion, 3 (5.1%) had NTRK3 imbalance, and 1 (1.7%) case each showed MYO5A::ROS1 and ESR1::CCDC170 fusion. In 51 cases with evaluable FISH (NTRK3) data, 33 (64.7%) were positive for NTRK3 rearrangement. Both the comparison of pan-TRK versus RNA-NGS and versus FISH (NTRK3) revealed high values of specificity (SP) and positive predictive value (PPV) (92.3%-96.2%) for the detection of NTRK3 fusions/rearrangements, despite a limited sensitivity (SE) of 36.4%. In the comparison of pan-TRK versus RNA-NGS and FISH (NTRK3), both SP and PPV were 100%, with a SE of 33.3%.</p><p><strong>Conclusions: </strong>Our 'optimized' pan-TRK protocol achieved high SP and PPV for the detection of NTRK3 fusions/rearrangements in PSCNs, despite a limited sensitivity compared to molecular assay. These results suggest that this protocol may serve as a diagnostic tool in routine practice, effectively guiding molecular testing and refining the diagnostic workflow for PSCNs.</p>","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":" ","pages":""},"PeriodicalIF":3.8,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149136330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HistopathologyPub Date : 2026-10-08DOI: 10.1111/his.70293
Edward Hadi, Mihir Gudi, Xiaoxian Li, Sandra O'Toole, Ales Ryska, Gary Tse, Sunil Lakhani, Stuart Schnitt, Ian Ellis, Emad Rakha, Puay Hoon Tan
{"title":"Mitoses counting in phyllodes tumours: rationale for a standardized hotspot-based approach.","authors":"Edward Hadi, Mihir Gudi, Xiaoxian Li, Sandra O'Toole, Ales Ryska, Gary Tse, Sunil Lakhani, Stuart Schnitt, Ian Ellis, Emad Rakha, Puay Hoon Tan","doi":"10.1111/his.70293","DOIUrl":"10.1111/his.70293","url":null,"abstract":"<p><strong>Background: </strong>Breast phyllodes tumours (PTs) are rare biphasic fibroepithelial neoplasms, classified into benign, borderline and malignant categories. Stromal mitotic activity is a key criterion in grading PT, but the methodology for mitotic assessment has not been clearly articulated.</p><p><strong>Materials and methods: </strong>We discuss the approach to determining stromal mitotic activity in PTs. Whether the most mitotically active area (hotspot) or an average count across several tumour regions should be adopted is reviewed. We also outline the operational protocol for mitotic hotspot evaluation, accounting for different microscope models with varying field diameters.</p><p><strong>Results: </strong>A standardized method of determining stromal mitoses in PTs is recommended in order to improve interobserver reproducibility and accuracy in grading PTs. The application of digital tools in stromal mitotic counting is also addressed.</p><p><strong>Conclusion: </strong>We advocate using the hotspot method of obtaining the highest stromal mitotic count, together with other histological parameters, to classify PTs.</p>","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":" ","pages":""},"PeriodicalIF":3.8,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149136379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HistopathologyPub Date : 2026-10-08DOI: 10.1111/his.70294
Sunayana Misra, Lisa Centeno, Dupinder Singh, Romil Saxena, Rifat Mannan
{"title":"Cyclin-dependent kinase 4/6 (CDK4/6) inhibitor-induced hepatotoxicity and its resolution: a study of seven cases.","authors":"Sunayana Misra, Lisa Centeno, Dupinder Singh, Romil Saxena, Rifat Mannan","doi":"10.1111/his.70294","DOIUrl":"https://doi.org/10.1111/his.70294","url":null,"abstract":"<p><strong>Aims: </strong>Hepatotoxicity is an increasingly recognised and potentially dose-limiting adverse effect of CDK4/6 inhibitors, but their histopathological spectrum remains incompletely characterised. We aimed to describe the clinicopathological features of histologically characterised CDK4/6 inhibitor-induced liver injury.</p><p><strong>Methods and results: </strong>We retrospectively identified patients with metastatic breast cancer who developed liver enzyme elevation and underwent liver biopsy while receiving a CDK4/6 inhibitor at a single comprehensive cancer centre (2020-2024). Inclusion required a RUCAM score ≥6 and exclusion of alternative aetiologies. Seven female patients met the criteria (ribociclib, n = 6; palbociclib, n = 1). The mean interval to first enzyme elevation was 60 days (range 20-114) and the mean RUCAM score was 8. Antinuclear antibody (ANA) positivity was noted in three patients, with negative extended autoimmune panels. Liver biopsy demonstrated severe acute hepatitis in five patients (71.4%), mild lobular hepatitis in one (14.3%) and subacute hepatitis with early fibrosis in one (14.3%). All acute biopsies showed perivenular (zone 3) confluent necrosis, with additional bridging necrosis in three biopsies. Portal inflammation was identified in all biopsies and lymphocytic cholangitis in five (71.4%) biopsies. No ANA-positive patient showed histological features of autoimmune hepatitis. All patients achieved biochemical normalisation after drug withdrawal (mean 63 days from peak; range 30-129), and six were successfully switched to an alternative agent.</p><p><strong>Conclusions: </strong>CDK4/6 inhibitor-induced liver injury predominantly manifests as acute hepatocellular injury with zone 3 necrosis and lymphocytic cholangitis. Despite severe histological abnormalities, it resolves with drug withdrawal, and limited cross-reactivity between agents supports individualised therapeutic strategies.</p>","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":" ","pages":""},"PeriodicalIF":3.8,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149136324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HistopathologyPub Date : 2026-10-08DOI: 10.1111/his.70295
Yuri Merlotti Gomes, João Pedro Dos Reis da Costa, Roberto Bonfim Pimenta Peixoto, João Henrique Quintão, Solange Moraes Sanches, Almir Galvão Vieira Bitencourt, Fabiana Baroni Alves Makdissi, Renato Cagnacci Neto, Guilherme Rocha Melo Gondim, Emílio Marcelo Pereira, Cynthia Aparecida Bueno de Toledo Osório, Helenice Gobbi, Marina De Brot, Rodrigo Fonseca Abreu
{"title":"Do alternative classification systems improve prognostication in phyllodes tumours of the breast? A comparative clinicopathological study.","authors":"Yuri Merlotti Gomes, João Pedro Dos Reis da Costa, Roberto Bonfim Pimenta Peixoto, João Henrique Quintão, Solange Moraes Sanches, Almir Galvão Vieira Bitencourt, Fabiana Baroni Alves Makdissi, Renato Cagnacci Neto, Guilherme Rocha Melo Gondim, Emílio Marcelo Pereira, Cynthia Aparecida Bueno de Toledo Osório, Helenice Gobbi, Marina De Brot, Rodrigo Fonseca Abreu","doi":"10.1111/his.70295","DOIUrl":"https://doi.org/10.1111/his.70295","url":null,"abstract":"<p><strong>Aims: </strong>Phyllodes tumours of the breast (PTs) present complex histological features that challenge classification. The WHO 5th Edition (2019) defines malignancy based on five simultaneous criteria, which may under-recognize tumours with metastatic potential. Alternative diagnostic systems have been proposed, but comparative data are limited.</p><p><strong>Methods and results: </strong>We reviewed 62 PTs diagnosed as borderline or malignant between 2015 and 2025. Histological features were re-evaluated, and tumours were classified according to WHO (2019), Tan et al. (2025), and the Refined Criteria (2023). After exclusion of 4 reclassified benign cases, 58 tumours (42 borderline, 16 malignant) were analysed. The mean patient age was 45 years, and the mean tumour size was 6.7 cm. After a median follow-up of 31.7 months, 6 borderline PTs recurred locally without metastasis. Among malignant PTs, seven developed distant metastases, with two disease-related deaths. High stromal mitotic activity (≥30/10 HPF, P = 0.005) and malignant heterologous elements (P < 0.001) were independently associated with metastasis. Tan et al.'s classification showed 97% concordance with WHO 2019, whereas the Refined Criteria reclassified 52% of borderline tumours as malignant; none of the reclassified tumours developed distant metastases during the available follow-up.</p><p><strong>Conclusions: </strong>In this cohort, high stromal mitotic activity and malignant heterologous elements were the strongest predictors of recurrence in PTs. Tan et al.'s classification system demonstrated close concordance with the WHO (2019) criteria, whereas the Refined Criteria classified a substantially greater proportion of tumours as malignant without improving prognostic discrimination during the available follow-up period. Comprehensive tumour sampling remains essential for accurate classification and reliable prognostic assessment of PTs of the breast.</p>","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":" ","pages":""},"PeriodicalIF":3.8,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149136374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HistopathologyPub Date : 2026-10-08DOI: 10.1111/his.70296
Min Han, Maria B de Leon, Yu Liang, Matthew L Hedberg
{"title":"A rare postradiation vaginal vascular lesion: not an angiosarcoma.","authors":"Min Han, Maria B de Leon, Yu Liang, Matthew L Hedberg","doi":"10.1111/his.70296","DOIUrl":"https://doi.org/10.1111/his.70296","url":null,"abstract":"","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":" ","pages":""},"PeriodicalIF":3.8,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149127412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HistopathologyPub Date : 2026-10-07Epub Date: 2026-07-02DOI: 10.1111/his.70226
Michael Minkley, Kashif Ravasia, Thi Nghiem, Dongxia Gao, Jamie Feng, Andrew Churg, Julia R Naso
{"title":"TROP2 immunoreactivity in pulmonary large cell neuroendocrine carcinoma","authors":"Michael Minkley, Kashif Ravasia, Thi Nghiem, Dongxia Gao, Jamie Feng, Andrew Churg, Julia R Naso","doi":"10.1111/his.70226","DOIUrl":"10.1111/his.70226","url":null,"abstract":"<div>\u0000 \u0000 <section>\u0000 \u0000 <h3> Introduction</h3>\u0000 \u0000 <p>TROP2 antibody-drug conjugates have shown promising anti-tumour activity, but neither the activity of these agents nor TROP2 expression has been well studied in pulmonary large cell neuroendocrine carcinoma (LCNEC), a rare and aggressive cancer type. We aimed to (i) determine the prevalence of TROP2 immunoreactivity in LCNEC; (ii) assess whether TROP2 immunoreactivity in LCNEC is related to RB1 loss on IHC or to the presence of NSCLC or SCLC components and (iii) determine whether TROP2 immunoreactivity in LCNEC has prognostic significance.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>TROP2 immunohistochemistry was performed on 58 pure LCNECs and 25 areas of LCNEC that were combined with other carcinomas, in tissue microarray format. TROP2 was scored for the percent of tumour cells staining, and with evaluation of cytoplasmic versus membranous staining, approximating a previously published predictive scoring method.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>TROP2 staining in ≥1% and ≥50% of LCNEC cells was present in 60% and 26% of pure LCNEC tumours, respectively. Cytoplasmic-type staining, previously implicated in greater antibody-drug conjugate response, was present in 48% of pure LCNEC cases. Positive TROP2 staining was less frequent in pure LCNEC than in the LCNEC component of tumours that also contained a NSCLC component (≥1%: <i>P</i> = 0.0087; ≥50%: <i>P</i> = 0.011), and ≥50% TROP2 staining in pure LCNEC was associated with retained RB1 staining on immunohistochemistry (<i>P</i> = 0.032). TROP2 staining was not associated with recurrence-free survival or disease-specific survival outcomes.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Frequently positive TROP2 IHC suggests that TROP2 antibody-drug conjugates may be potential treatments for LCNEC.</p>\u0000 </section>\u0000 </div>","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":"89 5","pages":"779-785"},"PeriodicalIF":3.8,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/his.70226","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148368192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HistopathologyPub Date : 2026-10-07Epub Date: 2026-04-23DOI: 10.1111/his.70163
Richard Wing-Cheuk Wong, Karen L Talia, W Glenn McCluggage
{"title":"Glandular lesions of the vagina: a review of a group of rare lesions","authors":"Richard Wing-Cheuk Wong, Karen L Talia, W Glenn McCluggage","doi":"10.1111/his.70163","DOIUrl":"10.1111/his.70163","url":null,"abstract":"<p>Primary carcinomas of the vagina are uncommon tumours, accounting for <1% of female cancers; these are also less common than metastatic carcinoma, which constitutes a significant majority of vaginal epithelial neoplasms. The most common primary tumour type is squamous cell carcinoma. Primary adenocarcinomas of the vagina are extremely rare and of various morphological types, many of which are broadly similar to those arising in the cervix. When faced with a probable primary vaginal adenocarcinoma, the pathologist faces a dilemma since the normal vagina does not contain glands, making the origin difficult to explain, and a metastasis should always be excluded. In this review, we discuss primary vaginal adenocarcinomas and provide practical points for the pathologist in typing and reporting these neoplasms and in excluding a metastasis. We also review rare benign vaginal glandular lesions, neoplastic and non-neoplastic.</p>","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":"89 5","pages":"731-757"},"PeriodicalIF":3.8,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147770064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
HistopathologyPub Date : 2026-10-07Epub Date: 2026-06-26DOI: 10.1111/his.70228
Graham Stoddard, Rabeka Ali, Ozlen Saglam
{"title":"Navigating diagnostic challenges in low-grade spindle cell lesions of the breast: a retrospective review","authors":"Graham Stoddard, Rabeka Ali, Ozlen Saglam","doi":"10.1111/his.70228","DOIUrl":"10.1111/his.70228","url":null,"abstract":"<div>\u0000 \u0000 <section>\u0000 \u0000 <h3> Aims</h3>\u0000 \u0000 <p>Low-grade spindle cell lesions of the breast (LGSCL-B) are uncommon, with malignant counterparts being particularly rare. Management recommendations for desmoid-type fibromatosis (DF), in particular, have evolved.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods and Results</h3>\u0000 \u0000 <p>A retrospective review of cases from 2000 to 2024 was conducted using LGSCL-B-related keyword searches. Clinical features were assessed, and when available, core needle biopsy (CNB) findings were correlated with excision specimens and imaging. Of 68 LGSCL-B samples, DF was the most frequent subtype (28 cases, 41%). A total of six resections were negative for β-catenin expression, including three resections from cases diagnosed as DF and three resections from cases categorized as undetermined on CNB and subsequently finalized as DF on resection. Myofibroblastoma occurred in 12 patients, more often in men (58%), with lipid-rich (<i>n</i> = 3) and myxoid (<i>n</i> = 2) variants. One lesion initially diagnosed as a solitary fibrous tumour was reclassified as a palisaded myofibroblastoma. Malignancy was identified in two biopsies: a spindle cell sarcoma and a fibromatosis-like metaplastic carcinoma; the latter was reclassified at resection as a malignant phyllodes tumour with heterologous bone formation. Thirteen CNB (19%) were indeterminate, including one described with ambiguous wording, a spindle cell sarcoma with a differential encompassing both benign and malignant entities.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Most LGSCL-B can be classified on CNB, but approximately one-fifth yield indeterminate results. Diagnostic challenges include overlapping morphological features, immunohistochemical profiles and potential reclassification at resection. Awareness of these pitfalls, along with selective use of adjunct molecular testing, may enhance diagnostic accuracy and reduce overtreatment.</p>\u0000 </section>\u0000 </div>","PeriodicalId":13219,"journal":{"name":"Histopathology","volume":"89 5","pages":"786-795"},"PeriodicalIF":3.8,"publicationDate":"2026-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148338421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}