Applied immunohistochemistry & molecular morphology : AIMM最新文献

{"title":"Evaluation of Diagnostic Accuracy of Immunohistochemical Markers of SATB2 and Villin in Differential Diagnosis of Ovarian and Gastrointestinal Mucinous Carcinoma.","authors":"Mehrjoo Amraie, Mohammadhossein Khorraminejad-Shirazi, Ali Nabavizadeh, Maral Mokhtari","doi":"10.1097/PAI.0000000000001265","DOIUrl":"10.1097/PAI.0000000000001265","url":null,"abstract":"<p><p>Determining the origin of mucinous adenocarcinomas can be challenging due to overlapping histologic and immunohistochemical features. This study evaluates the utility of SATB2 and villin immunohistochemical markers for defining mucinous adenocarcinomas' origin. We retrospectively analyzed 71 patients with mucinous adenocarcinomas-31 lower gastrointestinal (GI), 28 ovarian, and 12 cases of pseudomyxoma peritonei. Immunohistochemistry for SATB2 and villin was performed on ovarian and GI tumor samples. Sensitivity, specificity, and positive and negative predictive values were calculated to assess diagnostic performance.For identifying GI origin, SATB2 showed 87.1% sensitivity and 100% specificity, while villin exhibited 93.5% sensitivity but only 21.4% specificity. Dual SATB2/villin positivity demonstrated 80.6% sensitivity and 100% specificity for GI origin. For ovarian origin, dual SATB2/villin negativity provided 100% specificity. Logistic regression analysis on the adenocarcinoma cases showed 93.2% accuracy rate of dual staining with SATB2 and villin for predicting GI versus ovarian origin. SATB2 exhibits high specificity for GI mucinous adenocarcinomas, and villin is highly sensitive. Combining SATB2 and villin optimizes diagnostic performance for differentiating the primary origin site of mucinous adenocarcinomas and determining pseudomyxoma peritonei origin. Moreover, the presence of signet ring morphology prompted reconsideration of possible GI origin among our cases. A multimarker immunohistochemical panel, including SATB2 and villin can enhance the diagnostic accuracy of challenging mucinous adenocarcinoma cases.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"257-263"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144121977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Value of Routine Reflex In Situ Hybridization Testing in Low-grade Tubule-forming Invasive Breast Cancers With Equivocal HER2 Immunohistochemistry: A Reappraisal of the ASCO/CAP Guidelines.","authors":"Seyed Reza Taha, Fouad Boulos","doi":"10.1097/PAI.0000000000001269","DOIUrl":"10.1097/PAI.0000000000001269","url":null,"abstract":"<p><p>Guidelines from the American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP) recommend an equivocal score (2+) and reflex in situ hybridization (ISH) testing for invasive breast cancer (IBC) with moderate to strong lateral or basolateral staining by HER2 immunohistochemistry (IHC). While this recommendation mainly addresses aggressive tumor types such as micropapillary carcinoma, it is applied to low-grade, tubule-forming IBCs unlikely to show HER2 amplification. A total of 62 cases of IBC with equivocal HER2 IHC, low histologic grade (1/3), and tubule formation scores of 1 or 2 according to Nottingham criteria were retrospectively identified from 2020 to 2023 to determine the frequency of HER2 amplification using fluorescent ISH (FISH). Following slide review, 3 cases were reclassified as grade 2, leaving 59 cases for analysis. Demographic and clinicopathological data were collected from medical records and analyzed. A total of 98.3% of cases were not amplified by HER2 FISH, with only 1 case showing amplification. All cases were ER positive. Oncotype DX scores, available for select cases, showed low recurrence scores (below 25). The single HER2-amplified case contained a ductal carcinoma in situ component with HER2 3+ staining, potentially leading to a false positive result. In conclusion, HER2 amplification is rare in low-grade, tubule-forming IBCs. These results suggest reconsidering current guidelines to reduce unnecessary FISH testing, potentially improving cost-effectiveness and clinical efficiency without compromising diagnostic accuracy.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"204-210"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144164482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Expression and Clinical Features of 8 Immunohistochemistry Markers in Adrenal Cortical Adenomas and Pheochromocytomas.","authors":"Zhi Chen Liu, Wen Ming Tang, Li Jun Zhou, Yong Hui Zhang, Jia Hao Zhang, Liang Yan, Jun Li, Hai Hang Feng, Xiao Ming Li, Chun Li","doi":"10.1097/PAI.0000000000001271","DOIUrl":"10.1097/PAI.0000000000001271","url":null,"abstract":"<p><p>This study explores the potential relationship between 8 immunohistochemistry markers and 4 adrenal diseases-cushing syndrome, primary hyperaldosteronism, nonfunctioning adrenal adenoma, and hypercatecholamine-based on symptoms and laboratory findings. Understanding these associations can provide valuable insights into the diagnosis and management of adrenal tumors. We retrospectively analyzed cases of patients treated in the urology department of our hospital from April 2017 to May 2022, focusing on pathologic results of specimens that had undergone immunohistochemical staining following laparoscopic adrenalectomy. The statistical analysis was performed using the χ 2 test with SPSS 25.0 software. A total of 124 cases were collected, including 71 men and 53 women. Among them, 21 cases were diagnosed with cushing syndrome, 49 with primary hyperaldosteronism, and 40 with nonfunctioning adrenal adenoma, all reported as adrenal cortical adenomas. In addition, 14 cases were diagnosed with hypercatecholamine, reported as pheochromocytoma. The expression of Melan-A, inhibin α, and vimentin was significantly higher in adrenal cortical adenomas compared with pheochromocytoma ( P <0.05), while CgA and S100 were more noticeable in pheochromocytoma ( P <0.05). However, there was no significant difference in the expression of Syn, β-catenin, and CK between these 2 groups. Further comparisons revealed no significant differences among cushing syndrome, primary hyperaldosteronism, nonfunctioning adrenal adenoma, and hypercatecholamine concerning these 8 markers. The same applied when comparing nonfunctioning adrenal adenoma and functional adrenal adenoma (cushing syndrome and primary hyperaldosteronism). Our findings suggest that the combination of Melan-A, inhibin α, vimentin, CgA, and S100 may be useful in distinguishing between adrenal cortical adenoma and pheochromocytoma. However, these markers are not reliable for distinguishing among cushing syndrome, primary hyperaldosteronism, hypercatecholamine, and nonfunctioning adrenal adenoma.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"230-234"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12212469/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144259907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Immune Profiling of Incidental NSCLC Patients: Comparison Between Tumor Sections and TMA Cores.","authors":"Iusta Caminha, Juliana Cordeiro, Francisco Martins Neto, Marclesson Alves, Paulo G Silva, Guilherme Sousa, Fabio Tavora, Luciano Pamplona","doi":"10.1097/PAI.0000000000001266","DOIUrl":"10.1097/PAI.0000000000001266","url":null,"abstract":"<p><p>In the context of nonsmall cell lung cancer (NSCLC), the immune evasion strategy used by tumor cells involves the expression of immune checkpoint proteins, such as PD-L1, which suppress antitumor T-cell responses. The use of immune checkpoint inhibitors (ICIs) has significantly improved overall survival, overall response rate, and progression-free survival in NSCLC patients. This study aimed to evaluate the concordance of PD-L1 expression in NSCLC patients using tissue microarrays (TMA) as proxies for small biopsies. The degree of concordance among tissue cores and between the cores and the whole slide was reported. Furthermore, the presence of tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs) was analyzed to investigate the correlation between PD-L1 expression and immune cell infiltration. The study included 13 paraffin-embedded tissue samples from patients incidentally diagnosed with lung cancer during COVID imaging studies. Tissue microarrays were constructed using a manual tissue arrayer, and 4 cores of 2 mm diameter of representative areas were selected from the hematoxylin-eosin-stained sections from lung tumor specimens. Immunohistochemical analyses were performed to assess PD-L1 positivity, tumor macrophage infiltrate, and T-cell infiltrate. The density of CD8+ T cells was evaluated as the overall percentage of the area within the borders of the tumors covered by positive immune cells. Results demonstrated that PD-L1 expression showed a high degree of concordance between TMA cores and whole tumor sections, suggesting that small samples could reliably represent whole tumor PD-L1 status. However, the densities of CD8+ T cells and CD68+ macrophages varied significantly. TMA cores typically underrepresented the density of these immune cells compared with whole sections, particularly for CD68+ macrophages, which exhibited lower densities in TMAs, used as proxies for small biopsies. This study contributes to the understanding of how the heterogeneity of PD-L1 expression and immune cell distribution can influence the detection and scoring of these parameters, highlighting the importance of comprehensive immune profiling in guiding personalized cancer immunotherapy.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"218-229"},"PeriodicalIF":0.0,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144201305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Clive R. Taylor: A Tribute.","authors":"Richard J Cote","doi":"10.1097/PAI.0000000000001130","DOIUrl":"https://doi.org/10.1097/PAI.0000000000001130","url":null,"abstract":"","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":"31 7","pages":"439-444"},"PeriodicalIF":0.0,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144145302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expression of Proteinase-activated Receptor 2 (PAR2) as a Correlate of Concern in Triple-negative Breast Cancer (TNBC).","authors":"Gargi Kapatia,&nbsp;Subhpreet Kaur,&nbsp;Sandeep Kumar,&nbsp;Ishita Laroiya,&nbsp;Gurpreet Singh,&nbsp;Maryada Sharma,&nbsp;Amanjit Bal,&nbsp;Manni Luthra-Guptasarma","doi":"10.1097/PAI.0000000000001025","DOIUrl":"https://doi.org/10.1097/PAI.0000000000001025","url":null,"abstract":"<p><strong>Purpose: </strong>Triple-negative breast cancer (TNBC), a highly aggressive cancer with poor outcome and lacking specific diagnostic, prognostic, or targeted therapeutic strategies, constitutes roughly 20% of all breast cancer cases. TNBC cells lack receptors for estrogen, progesterone, and human epidermal growth factor. The effort continues to find a suitable correlate that could serve as a TNBC biomarker, or as therapeutic target, or both.</p><p><strong>Materials and methods: </strong>A retrospective study was performed with 88 TNBC and 74 non-TNBC patients who had undergone mastectomy/lumpectomy with axillary clearance for carcinoma breast. Immunohistochemical staining was carried out for levels of proteinase-activated receptor 2 (PAR2), encoded by F2RL1 gene, and staining scores were calculated, based on intensity and percentage positivity.</p><p><strong>Results: </strong>PAR2 levels were markedly upregulated in TNBC patients, compared with patients with other breast cancer subtypes. Amongst different non-TNBC subtypes, higher expression was noted in luminal B (88.8%) and HER2+ (100%), compared with luminal A (52.5%). PAR2 levels were significantly high in TNBC patients with age more than 40 years than corresponding patients of non-TNBC group (P=0.0017). Furthermore, there was a statistically significant increase in levels of PAR2 expression in lymph node negative (P=0.0096) and early stage (P=0.005) of TNBC versus non-TNBC patients. PAR2 staining of ductal carcinoma in situ and invasive ductal carcinoma revealed lower expression in invasive component.</p><p><strong>Conclusions: </strong>Our data suggest that PAR2 levels constitute a correlate of concern for TNBC, tying in with a recent report that higher levels of F2RL1 gene expression correlate with poorer disease-free, as well as overall survival in TNBCs.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"446-452"},"PeriodicalIF":1.6,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40578348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detecting Green Fluorescent Protein-tagged Cryptococcus neoformans by Immunofluorescence on Paraffin-embedded Brain Sections.","authors":"Chen Wenbiao,&nbsp;Zhong Yingcai,&nbsp;Zhu Longkun","doi":"10.1097/PAI.0000000000000976","DOIUrl":"https://doi.org/10.1097/PAI.0000000000000976","url":null,"abstract":"<p><p>Cryptococcus neoformans is an important pathogen causing opportunistic fungal meningitis. The pathogenic mechanism of cryptococcal meningitis remains unclear. We aimed to describe a practical approach for studying the pathologic features of cryptococcal central nervous system infection by immunofluorescence on paraffin-embedded brain of mice using different antigen retrieval methods. After 14 days of intratracheal inoculation of green fluorescent protein-tagged C. neoformans (H99-GFP), C57BL/6J mice brains were fixed in 4% paraformaldehyde and embedded in paraffin. Antigen retrieval methods such as microwaves, 1% sodium lauryl sulfate, 1 N HCl, pepsase, and tryptase were used on 5-μm paraffin sections and the effects were compared. The green fluorescence of H99-GFP persisted with antigen retrieval using 1% sodium lauryl sulfate. After immunofluorescent staining, H99-GFP, glial fibrillary acidic protein-tagged astrocytes, and ionized calcium-binding adapter molecule 1-tagged microglia could be observed clearly. Based on our results, we provide a practical approach for the further study of the interaction between C. neoformans and brain cells.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"72-77"},"PeriodicalIF":1.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39446871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relationship Between O-GlcNAcase Expression and Prognosis of Patients With Osteosarcoma.","authors":"Thamonwan Sombutthaweesri,&nbsp;Shuangjiang Wu,&nbsp;Nutchapon Chamusri,&nbsp;Jongkolnee Settakorn,&nbsp;Dumnoensun Pruksakorn,&nbsp;Parunya Chaiyawat,&nbsp;Thanapat Sastraruji,&nbsp;Suttichai Krisanaprakornkit,&nbsp;Chayarop Supanchart","doi":"10.1097/PAI.0000000000000970","DOIUrl":"https://doi.org/10.1097/PAI.0000000000000970","url":null,"abstract":"<p><p>Several studies have demonstrated a role of O-GlcNAcylation (O-GlcNAc) in tumorigenesis of various carcinomas by modification of tumor-associated proteins. However, its implication in the pathogenesis of osteosarcoma remains unclear. This study aimed to investigate the levels of O-GlcNAc and the expressions of O-linked N-acetylglucosamine transferase (OGT) and O-GlcNAcase (OGA) in human osteosarcoma tissues, by using immunohistochemistry; and to find correlations between the levels or expressions and several clinicopathologic parameters. There were 109 first diagnosed osteosarcoma patients, including Enneking stage IIB (n=70) and III (n=39). Correlations between the immunoreactive score (IRS) and clinicopathologic parameters, overall survival, and metastasis-free survival were evaluated. A positive correlation was found between the IRS of OGA and the percentage of postchemotherapeutic tumor necrosis (r=0.308; P=0.017). Univariate analysis revealed significantly lower OGA IRS in metastatic patients (P=0.020) and poor chemotherapeutic-responder patients (P=0.001). By multivariate analysis, presence of tumor metastasis (P=0.002) and lower OGA IRS (P=0.004) was significantly associated with shorter overall survival. Subgroup analysis in stage IIB osteosarcoma (n=70) demonstrated that male sex (P=0.019), presence of tumor recurrence (P=0.026), poor chemotherapeutic responder (P=0.022), and lower OGA IRS (P=0.019) were significantly correlated with short metastasis-free survival. But, lower OGA IRS was the only independent predictor for short metastasis-free survival (P=0.006). Our findings suggested that O-GlcNAc pathway, especially OGA, may involve in pathogenesis and aggressiveness of osteosarcoma. Low level of OGA expression may be used as a poor prognostic indicator.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"e1-e10"},"PeriodicalIF":1.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39374696","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Histologic and Molecular Characterization of Non-Small Cell Lung Carcinoma With Discordant ROS1 Immunohistochemistry and Fluorescence In Situ Hybridization.","authors":"Diane M Wilcock,&nbsp;Robert L Schmidt,&nbsp;Larissa V Furtado,&nbsp;Anna P Matynia,&nbsp;Georgios Deftereos,&nbsp;Deepika Sirohi","doi":"10.1097/PAI.0000000000000973","DOIUrl":"https://doi.org/10.1097/PAI.0000000000000973","url":null,"abstract":"<p><strong>Introduction: </strong>ROS1 immunohistochemical (IHC) positivity requires follow-up with confirmatory testing such as fluorescence in situ hybridization (FISH). Identifying predictive characteristics of false positive ROS1 IHC cases could aid in optimizing testing algorithms, decrease testing costs and preserve tissue.</p><p><strong>Materials and methods: </strong>Retrospective results were retrieved for 2054 patients with non-small cell lung carcinoma submitted to our laboratory for molecular testing. Reflex ROS1 FISH was done on all ROS1 immunoreactive cases using ROS1 D4D6 antibody. Staining intensity and histo-score was recorded for all ROS1 immunoreactive cases. Results of any additional molecular testing (KRAS, BRAF, EGFR, ALK FISH, RET FISH, MET FISH) were also tabulated.</p><p><strong>Results: </strong>ROS1 immunoreactivity was seen in 305/2054 (14.8%) cases. Immunoreactivity was weak in majority of the cases with only 4.6% cases having an histo-score >100 and 5.9% of cases had moderate staining intensity. FISH was negative in 99% (302/305) cases with any degree of IHC expression (discordant cases) while 3 cases were positive by FISH. Diffuse strong IHC staining in greater than 90% of the tumor was noted in 6 cases, 3 (0.98%) of which were confirmed to have ROS1 rearrangement by FISH. The discordant cases had significantly higher rates of EGFR mutations (P<0.0005) in comparison to ROS1 IHC negative cases, were seen more often in adenocarcinoma and adenosquamous cell carcinoma (P<0.0005) with lepidic and acinar patterns, and more likely to occur in primary lung carcinomas (P<0.0005).</p><p><strong>Conclusions: </strong>False positive ROS1 immunoreactivity was very frequent, occurred more commonly in primary NSCLC cases with acinar and/or lepidic histologies and was more likely in EGFR mutated cases. Using higher positivity thresholds for ROS1 IHC and incorporating the histologic and molecular correlates into algorithmic strategies could result in increased specificity and clinical utility of ROS1 IHC assay.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"19-26"},"PeriodicalIF":1.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39446870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ERG Immunoreactivity in Blastic Hematolymphoid Neoplasms: Diagnostic Pitfall in the Workup of Undifferentiated Malignant Neoplasms.","authors":"Matthew Koo,&nbsp;Yasodha Natkunam","doi":"10.1097/PAI.0000000000000958","DOIUrl":"https://doi.org/10.1097/PAI.0000000000000958","url":null,"abstract":"<p><p>Undifferentiated malignant neoplasms pose diagnostic challenges, and reliable immunohistochemical markers with well-characterized staining profiles are desirable when characterizing them. Our initial observation of erythroblast transformation specific regulated gene-1 (ERG) reactivity in myeloid sarcomas led us to broadly explore the utility of ERG as a marker of immature hematolymphoid neoplasms presenting in extramedullary sites. We stained 207 immature and mature hematolymphoid lesions as well as 39 benign hematolymphoid tissues and found weak-to-moderate ERG immunopositivity in 15 of 16 (94%) acute myeloid leukemias/myeloid sarcomas, including 4 of 5 (80%) CD34-negative/CD117-negative acute myeloid leukemias/myeloid sarcomas. ERG positivity was also seen in all 9 cases of B-lymphoblastic and T-lymphoblastic leukemia/lymphoma, all 3 cases of hematogone hyperplasia, and all 4 cases of systemic mastocytosis. ERG was negative in 148 mature B-cell and T-cell lymphomas, including 2 high-grade B-cell lymphomas and 2 blastoid variant mantle cell lymphomas; 23 histiocytic/dendritic cell neoplasms; 2 indolent T-lymphoblastic proliferations; and 2 blastic plasmacytoid dendritic cell neoplasms. We conclude that ERG immunoreactivity may pose a significant diagnostic pitfall in the workup of undifferentiated malignant neoplasms, particularly those presenting in extramedullary sites.</p>","PeriodicalId":520562,"journal":{"name":"Applied immunohistochemistry & molecular morphology : AIMM","volume":" ","pages":"42-48"},"PeriodicalIF":1.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39184003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}