A Novel EPC1 :: KDM2B Fusion in High-grade Endometrial Stromal Sarcoma.

The spectrum of endometrial stromal sarcoma (ESS) has expanded substantially since the publication of the most recent World Health Organisation (WHO) Classification of Female Genital Tumours and the advent of widely available genomic testing. We describe a uterine mesenchymal tumor harboring a novel EPC1 :: KDM2B fusion, best classified within the umbrella of high-grade endometrial stromal sarcoma (HGESS). This tumor was composed of a uniform population of spindled cells with some myxoid stroma, a mitotic rate of up to 21/10 high-power fields, and a largely pushing margin with focal vascular invasion. Immunohistochemistry showed strong and diffuse cyclin D1 positivity while CD10, WT1, DOG1, CD117, CD34, CD99, S100, MelanA, SMA, desmin, and h-caldesmon were negative. The tumor was confined to the uterus and no recurrence has been detected thus far, albeit with a short follow-up interval of 9 mo.

Oncological Outcomes After Multidisciplinary Management of Breast Implant-Associated Anaplastic Large Cell Lymphoma (BIA-ALCL).

INTRODUCTION: Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is an uncommon type of non-Hodgkin lymphoma, associated with breast implant capsules. Despite improvements in our understanding of BIA-ALCL, communicating the prognosis to patients remains challenging due to limited long-term follow-up data. This has important implications for decision-making, including recommendations for subsequent reconstructive procedures. The aim of this study was to assess the longer-term oncological outcomes of patients receiving multidisciplinary treatment for BIA-ALCL. METHODS: This was a retrospective cohort study of BIA-ALCL patients treated at a tertiary referral unit. The data are presented using simple descriptive statistics. RESULTS: Between 2015 and 2022, 18 BIA-ALCL patients were treated at our institution. The median age at diagnosis was 48.5 (IQR 41-55) years. Ten patients developed BIA-ALCL after cosmetic breast augmentation, and 8 after breast reconstruction following mastectomy for cancer. All patients had a history of textured implant insertion. The median time from first implant surgery to diagnosis was 8.5 (IQR 7-12) years. All patients underwent en-bloc total capsulectomy with implant removal, and 2 received systemic therapy. Fifteen patients had Stage I (IA-IC) disease, 2 had Stage IIA and 1 Stage III BIA-ALCL, based on the TNM classification system. At a median follow-up of 45 (IQR 15-71) months, there were no episodes of local or systemic relapse or death. CONCLUSIONS: Surgical management for BIA-ALCL is sufficient in early-stage disease, and associated with excellent oncological outcomes. This information is reassuring for patients when discussing recurrence risk.

Parallel evolution of two distinct lymphoid proliferations in clonal haematopoiesis.

AIMS: Angioimmunoblastic T-cell lymphoma (AITL) is genetically characterized by TET2 and DNMT3A mutations occurring in haematopoietic progenitor cells, and late events (e.g. the RHOA-G17V mutation) associated with malignant transformation. As TET2/DNMT3A-mutated progenitor cells can differentiate into multilineage progenies and give rise to both AITL and myeloid neoplasms, they may also have the potential to lead to other metachronous/synchronous neoplasms. We report two cases showing parallel evolution of two distinct potentially neoplastic lymphoid proliferations from a common mutated haematopoietic progenitor cell population. METHODS AND RESULTS: Both cases presented with generalized lymphadenopathy. In case 1 (a 67-year-old female), an initial lymph node (LN) biopsy was dismissed as reactive, but a repeat biopsy showed a nodal marginal zone lymphoma (NMZL)-like proliferation with an increase in the number of T-follicular helper (TFH) cells. Immunohistochemistry, and clonality and mutational analyses by targeted sequencing of both whole tissue sections and microdissected NMZL-like lesions, demonstrated a clonal B-cell proliferation that harboured the BRAF-G469R mutation and shared TET2 and DNMT3A mutations with an underlying RHOA-G17V-mutant TFH proliferation. Review of the original LN biopsy showed histological and immunophenotypic features of AITL. In case 2 (a 66-year-old male), cytotoxic T-cell lymphoma with an increase in the number of Epstein-Barr virus-positive large B cells was diagnosed on initial biopsy. On review together with the relapsed biopsy, we identified an additional occult neoplastic TFH proliferation/smouldering AITL. Both T-cell proliferations shared TET2 and DNMT3A mutations while RHOA-G17V was confined to the smouldering AITL. CONCLUSIONS: In addition to demonstrating diagnostic challenges, these cases expand the potential of clonal haematopoiesis in the development of different lineage neoplastic proliferations.

Early detection of T-cell lymphoma with T follicular helper phenotype by RHOA mutation analysis.

Angioimmunoblastic T-cell lymphoma (AITL) and peripheral T-cell lymphoma with T follicular helper phenotype (PTCL-TFH) are a group of complex clinicopathological entities that originate from T follicular helper cells and share a similar mutation profile. Their diagnosis is often a challenge, particularly at an early stage, because of a lack of specific histological and immunophenotypic features, paucity of neoplastic T cells and prominent polymorphous infiltrate. We investigated whether the lymphoma-associated RHOA Gly17Val (c.50G>T) mutation, occurring in 60% of cases, is present in the early "reactive" lesions, and whether mutation analysis could help to advance the early diagnosis of lymphoma. The RHOA mutation was detected by quantitative polymerase chain reaction with a locked nucleic acid probe specific to the mutation, and a further peptide nucleic acid clamp oligonucleotide to suppress the amplification of the wild-type allele. The quantitative polymerase chain reaction assay was highly sensitive and specific, detecting RHOA Gly17Val at an allele frequency of 0.03%, but not other changes in Gly17, nor in 61 controls. Among the 37 cases of AITL and PTCL-TFH investigated, RHOA Gly17Val was detected in 62.2% (23/37) of which 19 had multiple biopsies including preceding biopsies in ten and follow-up biopsies in 11 cases. RHOA Gly17Val was present in each of these preceding or follow-up biopsies including 18 specimens that showed no evidence of lymphoma by combined histological, immunophenotypic and clonality analyses. The mutation was seen in biopsies 0-26.5 months (mean 7.87 months) prior to the lymphoma diagnosis. Our results show that RHOA Gly17Val mutation analysis is valuable in the early detection of AITL and PTCL-TFH.

Angioimmunoblastic T-cell lymphoma contains multiple clonal T-cell populations derived from a common TET2 mutant progenitor cell.

Angioimmunoblastic T-cell lymphoma (AITL) is a neoplastic proliferation of T follicular helper cells with clinical and histological presentations suggesting a role of antigenic drive in its development. Genetically, it is characterized by a stepwise acquisition of somatic mutations, with early mutations involving epigenetic regulators (TET2, DNMT3A) and occurring in haematopoietic stem cells, with subsequent changes involving signaling molecules (RHOA, VAV1, PLCG1, CD28) critical for T-cell biology. To search for evidence of potential oncogenic cooperation between genetic changes and intrinsic T cell receptor (TCR) signaling, we investigated somatic mutations and T-cell receptor ß (TRB) rearrangement in 119 AITL, 11 peripheral T-cell lymphomas with T follicular helper phenotype (PTCL-TFH), and 25 PTCL-NOS using Fluidigm polymerase chain reaction (PCR) and Illumina MiSeq sequencing. We confirmed frequent TET2, DNMT3A, and RHOA mutations in AITL (72%, 34%, 61%) and PTCL-TFH (73%, 36%, 45%) and showed multiple TET2 mutations (2 or 3) in 57% of the involved AITL and PTCL-TFH. Clonal TRB rearrangement was seen in 76 cases with multiple functional rearrangements (2-4) in 18 cases (24%). In selected cases, we confirmed bi-clonal T-cell populations and further demonstrated that these independent T-cell populations harboured identical TET2 mutations by using BaseScope in situ hybridization, suggesting their derivation from a common TET2 mutant progenitor cell population. Furthermore, both T-cell populations expressed CD4. Finally, in comparison with tonsillar TFH cells, both AITL and PTCL-TFH showed a significant overrepresentation of several TRB variable family members, particularly TRBV19*01. Our findings suggest the presence of parallel neoplastic evolutions from a common TET2 mutant haematopoietic progenitor pool in AITL and PTCL-TFH, albeit to be confirmed in a large series of cases. The biased TRBV usage in these lymphomas suggests that antigenic stimulation may play an important role in predilection of T cells to clonal expansion and malignant transformation. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Aggressive B-cell lymphomas with a primary bone marrow presentation.

Aggressive B-cell lymphomas present as a heterogeneous spectrum of disease. A primary diagnosis in the bone marrow (BM) may be challenging in terms of diagnostic classification and clinical handling, owing to limited architectural information. Aggressive B-cell lymphomas can be subdivided into entities that typically present primarily in the BM, and cases with BM involvement in which the bulk of disease is present in other organs. One main topic at the 2018 BM workshop of the European Association of Haematopathology/Society of Hematopathology was therefore aggressive B-cell lymphomas with a primary BM presentation. The spectrum of cases submitted to this topic gave a good overview of commonly encountered problems, as well as unusual manifestations, and highlighted areas of imprecise disease definitions and diagnostic grey zones. The categories submitted to the workshop included cases of Burkitt lymphoma (BL) with unusual features, high-grade B-cell lymphomas (HG-BCLs) with and without so-called double/triple-hit, and diffuse large B-cell lymphomas (DLBCLs) with a primary BM presentation. Areas of difficulties included the morphological boundaries of HG-BCL not otherwise specified, cases with MYC and bcl-2 or bcl-6 translocations and terminal deoxynucleotidyl transferase (TdT) expression, which were categorised as B-cell lymphoblastic leukaemia/lymphoma if most cells showed TdT positivity, and the clinicopathological overlap between intravascular large B-cell lymphoma, CD5-positive DLBCL, and DLBCL with primary presentations in the BM, spleen, and liver. This review summarises our understanding of the main aggressive B-cell lymphoma categories with a common primary BM presentation and potential problem areas, and makes suggestions for the immunophenotypic and genetic work-up, illustrated by the interesting and challenging cases submitted to the workshop.

Sarcomatous Transformation in Undifferentiated/Dedifferentiated Endometrial Carcinoma: An Underrecognized Phenomenon and Diagnostic Pitfall.

Undifferentiated/dedifferentiated carcinoma is an aggressive endometrial carcinoma which remains underrecognized but may account for up to 9% of all endometrial malignancies. We describe 3 cases in which the undifferentiated component was associated with sarcomatous differentiation, characterized by spindled cells in 2 cases and heterologous malignant cartilage in 1 case. Two of the 3 cases demonstrated mismatch repair deficiency by immunohistochemistry. This phenomenon has not previously been formally reported and increases the likelihood of misdiagnosis, especially within biopsy samples; differential diagnoses may include endometrial stromal sarcoma and grade 3 endometrioid adenocarcinoma with spindled morphology. We review the current literature and provide strategies for resolving the differential diagnoses, with a suggested panel of antibodies which includes EMA, E-cadherin, and mismatch repair proteins as approximately 50% of cases show loss of mismatch repair expression.

Breast Implant-associated Anaplastic Large Cell Lymphoma: Review and Multiparametric Imaging Paradigms.

Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is a new provisional category in the 2016 World Health Organization (WHO) classification of lymphoid neoplasms, and its incidence is rising owing to increasing recognition of this complication of breast implant insertion. At a median of 10 years after implant insertion, the typical presenting features are sudden-onset breast swelling secondary to peri-implant effusion and less frequently mass-forming disease. Histologic features comprise pleomorphic cells expressing CD30 and negative anaplastic lymphoma kinase (ALK) receptor, similar to systemic and cutaneous ALK-negative anaplastic large cell lymphoma (ALCL). The effusion-only subtype is generally indolent and curable with surgery, unlike the more aggressive mass-forming disease, for which systemic therapy is advocated. High clinical suspicion and pertinent use of radiologic and pathology modalities are essential for timely and accurate diagnosis of BIA-ALCL. Contemporary imaging techniques including US, mammography, breast MRI, CT, and PET/CT are routinely used in breast disease and lymphomas; however, the unique behavior of BIA-ALCL presents significant diagnostic and radiologic interpretative challenges, with numerous nuanced imaging features being pertinent, and current lymphoma staging and response guidelines are not easily applicable to BIA-ALCL. The authors evaluate available evidence in this evolving field; detail key indications, strengths, and limitations of the panoply of radiologic techniques for BIA-ALCL; and propose multiparametric imaging paradigms for management of the peri-implant effusion and mass-forming or advanced disease subtypes, with the goal of accurate optimal patient care. The authors also predict a future model of multimodal assessment using novel imaging and molecular techniques and define key research directions. ©RSNA, 2020.

Expanding the morphological spectrum of ovarian microcystic stromal tumour.

AIMS: To expand the morphological spectrum of ovarian microcystic stromal tumour, a rare neoplasm considered to have a relatively constant morphology with microcysts, solid cellular regions and hyalinised fibrous stroma. METHODS AND RESULTS: We report four ovarian neoplasms in patients aged 45, 56, 61 and 71 years with the characteristic immunophenotype of microcystic stromal tumour (diffuse nuclear positivity with beta-catenin, cyclin D1 and WT1; diffuse cytoplasmic positivity with CD10; negative inhibin, calretinin, oestrogen receptor and progesterone receptor). The tumours had variant morphology (diffuse, nested and corded arrangements in three cases, including one with spindle cell elements; nested, corded and tubular in the other). A CTNNB1 point mutation in exon 3 (c.98C>G,p.S33C; c.100G>A,p.G34R; c.97T>G,p.S33A) was present in the three cases with material available for testing. CONCLUSIONS: We feel that the cases we report are related to microcystic stromal tumour but with variant morphology; as such, the morphological spectrum of ovarian microcystic stromal tumour is broader than hitherto reported.

An Unusual Case of YWHAE-NUTM2A/B Endometrial Stromal Sarcoma With Confinement to the Endometrium and Lack of High-Grade Morphology.

Endometrial stromal sarcoma (ESS) characterized by YWHAE-NUTM2A/B genetic fusion is a recently recognized entity that is classified as a high-grade (HG) ESS in the 2014 World Health Organization Classification. These are myoinvasive neoplasms and typically contain a monomorphous HG round-cell cyclinD1-positive component with or without an accompanying low-grade (LG) component that is only focally positive/negative for cyclinD1. We report a case of YWHAE-NUTM2A/B ESS in a 46-yr-old woman that showed a number of unusual histologic features, including being entirely confined to the endometrium with no myoinvasion or lymphovascular space invasion. The initial hysteroscopic biopsy showed a cyclinD1-positive classic LG ESS-like component which merged with a smaller cyclinD1 negative/focally positive fibroblastic component with no HG areas. YWHAE-NUTM2A/B genetic fusion was shown by real-time quantitative polymerase chain reaction and Sanger sequencing. In the subsequent hysterectomy specimen, the tumor was entirely confined to the endometrium and was largely composed of cellular and classic LG ESS-like areas (80%) which were strongly and diffusely positive for cyclinD1 and a focal fibroblastic component (20%) which was largely cyclinD1 negative. Despite the cellular areas showing mild nuclear enlargement, the entire tumor had a very low mitotic and proliferation index and showed strong and diffuse positivity for estrogen and progesterone receptors. The patient remains alive and well with no evidence of disease 14 mo following diagnosis. To our knowledge, this is the first reported case of YWHAE-NUTM2A/B ESS that is confined to the endometrium and which exhibits entirely LG morphology.

Comparison of optimised endovaginal vs external array coil T2-weighted and diffusion-weighted imaging techniques for detecting suspected early stage (IA/IB1) uterine cervical cancer.

OBJECTIVE: To compare sensitivity and specificity of endovaginal versus external-array coil T2-W and T2-W + DWI for detecting and staging small cervical tumours. METHODS: Optimised endovaginal and external array coil MRI at 3.0-T was done prospectively in 48 consecutive patients with stage Ia/Ib1 cervical cancer. Sensitivity/specificity for detecting tumour and parametrial extension against histopathology for a reading radiologist were determined on coronal T2-W and T2W + DW images. An independent radiologist also scored T2-W images without and with addition of DWI for the external-array and endovaginal coils on separate occasions >2 weeks apart. Cohen's kappa assessed inter- and intra-observer agreement. RESULTS: Median tumour volume in 19/38 cases positive on subsequent histology was 1.75 cm(3). Sensitivity, specificity, PPV, NPV were: reading radiologist 91.3 %, 89.5 %, 91.3 %, 89.5 %, respectively; independent radiologist T2-W 82.6 %, 73.7 %, 79.1 %, 77.8 % for endovaginal, 73.9 %, 89.5 %, 89.5 %, 73.9 % for external-array coil. Adding DWI improved sensitivity and specificity of endovaginal imaging (78.2 %, 89.5 %); adding DWI to external-array imaging improved specificity (94.7 %) but reduced sensitivity (66.7 %). Inter- and intra-observer agreement on T2-W + DWI was good (kappa = 0.67 and 0.62, respectively). CONCLUSION: Endovaginal coil T2-W MRI is more sensitive than external-array coil for detecting tumours <2 cm(3); adding DWI improves specificity of endovaginal imaging but reduces sensitivity of external-array imaging. KEY POINTS: • Endovaginal more accurate than external-array T2-W MRI for detecting small cervical cancers. • Addition of DWI improves sensitivity and specificity of endovaginal T2-W imaging. • Addition of DWI substantially reduces sensitivity of external-array T2-W imaging.