Mixed histiocytic neoplasms: A multicentre series revealing diverse somatic mutations and responses to targeted therapy.

Histiocytic neoplasms are diverse clonal haematopoietic disorders, and clinical disease is mediated by tumorous infiltration as well as uncontrolled systemic inflammation. Individual subtypes include Langerhans cell histiocytosis (LCH), Rosai-Dorfman-Destombes disease (RDD) and Erdheim-Chester disease (ECD), and these have been characterized with respect to clinical phenotypes, driver mutations and treatment paradigms. Less is known about patients with mixed histiocytic neoplasms (MXH), that is two or more coexisting disorders. This international collaboration examined patients with biopsy-proven MXH with respect to component disease subtypes, oncogenic driver mutations and responses to conventional (chemotherapeutic or immunosuppressive) versus targeted (BRAF or MEK inhibitor) therapies. Twenty-seven patients were studied with ECD/LCH (19/27), ECD/RDD (6/27), RDD/LCH (1/27) and ECD/RDD/LCH (1/27). Mutations previously undescribed in MXH were identified, including KRAS, MAP2K2, MAPK3, non-V600-BRAF, RAF1 and a BICD2-BRAF fusion. A repeated-measure generalized estimating equation demonstrated that targeted treatment was statistically significantly (1) more likely to result in a complete response (CR), partial response (PR) or stable disease (SD) (odds ratio [OR]: 17.34, 95% CI: 2.19-137.00, p = 0.007), and (2) less likely to result in progression (OR: 0.08, 95% CI: 0.03-0.23, p < 0.0001). Histiocytic neoplasms represent an entity with underappreciated clinical and molecular diversity, poor responsiveness to conventional therapy and exquisite sensitivity to targeted therapy.

Clinical characteristics, molecular aberrations, treatments, and outcomes of malignant histiocytosis.

Malignant histiocytosis (MH) is an extremely rare neoplasm of the macrophage-dendritic cell lineage. We report the clinical characteristics, molecular aberrations, treatments, and outcomes of patients with MH seen at two referral centers from January 2000 to May 2023. We identified 43 patients with MH, of which 26 had histiocytic sarcoma (MH-H), 9 interdigitating dendritic cell sarcoma (MH-IDC), and 8 Langerhans cell sarcoma (MH-LC). The median age at diagnosis was 61 years (range, 3-83). Thirty-three patients (77%) had multifocal disease, while 10 had unifocal involvement. Tumor specimens from 22 patients (51%) underwent targeted next generation sequencing, and 19 of 22 (86%) had at least one pathogenic mutation, including mutations in MAPK pathway genes (73%). The median overall survival (OS) among the entire cohort was 16 months (95% CI: 8-50). The outcomes of those with multifocal disease were significantly shorter than their unifocal counterpart: median OS of 10 months versus 50 months (p = .07). Patients with risk organ involvement (bone marrow, spleen, or liver) had significantly inferior outcomes. Chemotherapy and surgery were the most common first-line treatments for multifocal and unifocal disease, respectively. While the outcome for patients with multifocal disease was poor, there was a subset of patients who had durable responses to treatment. Our study highlights that MH has heterogeneous clinical presentation, frequent oncogenic mutations, and prognosis, which is strongly tied to disease extent and type of organ involvement.

Utility of end of induction bone marrow biopsy and survival outcomes in acute promyelocytic leukemia treated with fixed-dose induction regimen.

Significant variations exist related to the end of induction practices in the management of Acute Promyelocytic Leukemia (APL). These variations include all-trans retinoic acid (ATRA)-arsenic trioxide (ATO) in fixed doses versus continuation until hematologic complete remission (CR) and performance versus omission of post-induction bone marrow biopsy to confirm morphological CR. A retrospective chart review was conducted of 61 patients (42 low/intermediate-risk and 19 high-risk) aged ≥ 18 years with newly diagnosed APL treated with fixed duration ATRA-ATO +/- cytoreduction at a tertiary medical center from December 2012 through March 2020. Of the 54 patients with post-induction bone marrow biopsy results, 52 (96%) demonstrated no morphologic evidence of APL while the remaining were equivocal. After 2.6 years median follow-up, no relapses occurred. The estimated 2-year overall survival rate of 95% suggests excellent outcomes with a fixed ATO induction regimen and safe omission of post-induction bone marrow biopsy irrespective of hematologic parameters.

Spectrum of second primary malignancies and cause-specific mortality in pediatric and adult langerhans cell histiocytosis.

With the advent of targeted therapeutics in Langerhans cell histiocytosis (LCH), there is a growing survivor population that might be at risk for late mortality from non-LCH causes, including second primary malignancies (SPMs). We undertook a large study using the Surveillance, Epidemiology, and End Results (SEER) database to evaluate the patterns of SPMs and cause-specific mortality among individuals with LCH (2000-2016) from the US. We found an increased risk of SPMs in the cohort (standardized incidence ratio [SIR] 2.07). The pediatric group was at a high risk of developing Hodgkin lymphoma (SIR 60.93) and non-Hodgkin lymphoma (SIR 60.88). People with adult-onset LCH were found to have a high risk of developing miscellaneous malignant cancers (SIR 11.43), which primarily included myelodysplastic syndrome. Adults were also at a high risk of developing carcinoma in-situ of vulva at 2-11 months [SIR 62.72] and B-ALL at 60-119 months [SIR 66.29] after LCH diagnosis. Additionally, 5% and 1% of the patients developed prior or concomitant malignancies with LCH, respectively. The 5 yr overall survival (OS) was 96.6% for pediatric and 88.5% for adult LCH cohorts. Most common cause of death was infections in pediatric and SPMs in adult LCH. Our study highlights that despite advances in treatments, people with LCH have an increased mortality risk from non-LCH causes when compared with the general population, including a high risk of SPMs.

Outcomes After Treatment With Cobimetinib in Patients With Rosai-Dorfman Disease Based on KRAS and MEK Alteration Status.

Importance: Rosai-Dorfman disease (RDD) is a rare histiocytic neoplasm with recent studies showing alterations in the MAPK pathway, most commonly in the KRAS and MEK genes in about 40% of patients. Reports on the use of MEK-inhibitor therapy in RDD have been limited to small case studies. There are no approved treatments for this neoplasm, and therefore patients with RDD need efficacious treatments. Objective: To study the outcomes after treatment with cobimetinib based on MAPK pathway alterations in patients with RDD. Design, Setting, and Participants: This retrospective cohort study conducted at 2 tertiary care centers included patients with RDD who underwent treatment with cobimetinib between January 1, 2013, and December 1, 2021. Cobimetinib was administered at a dosage of 20 to 60 mg orally once daily as a single agent for 21 days in a 28-day cycle. Pathology was centrally reviewed. Response assessment was centrally conducted and was based on the established positron emission radiography response criteria used for clinical trials of targeted therapies in histiocytosis. Main Outcomes and Measures: Main outcomes were overall response rate (ORR), progression-free survival (PFS), adverse events (AEs) of cobimetinib in the entire cohort, and ORRs and PFS based on MAPK pathway alterations in patients with RDD. Results: A total of 16 patients (median [range] age at cobimetinib initiation, 57 [31-74] years; 11 [69%] women) were included in the study. The median follow-up duration was 19.0 months (95% CI, 8.4-27.8 months). The ORR was 63% (n = 10), including 5 complete responses and 5 partial responses. Somatic alterations in the KRAS or MEK genes were detected in 8 (50%) patients. Patients with KRAS or MEK alterations had significantly higher ORR (88% vs 38%; P = .03), deeper responses (complete responses among responders: 71% vs 0%; P = .002), and better PFS (at 1 year, 100% vs 29% were free from progression or death, respectively; P < .001) compared with those without such alterations. Grade 2 or higher AEs occurred in 12 (75%) patients, and 9 (56%) required dose reduction or temporary/permanent treatment discontinuation due to AEs. Conclusions and Relevance: In this cohort study, treatment with cobimetinib was associated with positive outcomes in KRAS- or MEK-variant RDD. However, AEs requiring dose modifications were common.

Utility of Single-Gene Testing in Cancer Specimens.

Molecular testing is now considered the standard of care to screen for disease, confirm the diagnosis, guide management, and use target therapy. Currently, several testing strategies are being used. One of the most common strategies is single-gene testing, which is often conducted for known mutations, such as BRAF in melanoma and EGFR in lung cancer. Subsequently, next-generation sequencing (NGS), which tests many genes simultaneously, was developed using targeted gene panels, whole-exome, or whole-genome sequencing. Ordering the best diagnostic tool and choosing between single-gene testing and NGS depends on several factors. In this review, we discuss different single-gene testing methodologies and the impact of using them in comparison to NGS/multigene panel.

IDH1 inhibitor-induced neutrophilic dermatosis in a patient with acute myeloid leukemia.

Ivosidenib is an oral inhibitor of mutant Isocitrate dehydrogenase 1 (IDH1). It is approved for treatment of patients with relapsed or refractory IDH1-mutated acute myeloid leukemia (AML) and patients with newly diagnosed IDH1-mutated AML who are 75 years or older or those who are ineligible to receive intensive chemotherapy. While generally well tolerated, differentiation syndrome has been reported in 15-20% of patients. Here, we report a case of acute febrile neutrophilic dermatosis or Sweet's syndrome in conjunction with the use of ivosidenib for the treatment of relapsed AML. We discuss the clinical presentation of this rare entity, review relevant literature, and comment on its association with differentiation syndrome.

The Interpretation of Sequence Variants in Myeloid Neoplasms.

OBJECTIVES: To provide an overview of the challenges encountered during the interpretation of sequence variants detected by next-generation sequencing (NGS) in myeloid neoplasms, as well as the limitations of the technology with the goal of preventing the over- or undercalling of alterations that may have a significant effect on patient management. METHODS: Review of the peer-reviewed literature on the interpretation, reporting, and technical challenges of NGS assays for myeloid neoplasms. RESULTS: NGS has been integrated widely and rapidly into the standard evaluating of myeloid neoplasms. Review of the literature reveals that myeloid sequence variants are challenging to detect and interpret. Large insertions and guanine-cytosine-heavy areas prove technically challenging while frameshift and truncating alterations may be classified as variants of uncertain significance by tertiary analysis informatics pipelines due to their absence in the literature and databases. CONCLUSIONS: The analysis and interpretation of NGS results in myeloid neoplasia are challenging due to the varied number of detectable gene alterations. Familiarity with the genomic landscape of myeloid malignancies and knowledge of the tools available for the interpretation of sequence variants are essential to facilitate translation into clinical and therapy decisions.

Diagnostic utility of one-stop fusion gene panel to detect TFE3/TFEB gene rearrangement and amplification in renal cell carcinomas.

MiT family translocation renal cell carcinoma (MiT-RCC) harbors translocations involving the TFE3 or TFEB genes. RCC with TFEB amplification is also identified and is associated with a more aggressive clinical course. Accurate diagnosis of MiT-RCC is crucial for patient management. In this study, we evaluated the performance of the Archer FusionPlex assay for detection of MiT-RCC with TFE3 or TFEB translocations and TFEB amplifications. RNA was extracted from 49 RCC FFPE tissue samples with known TFE3/TFEB status (26 TFE3 FISH positive, 12 TFEB FISH positive, 4 TFEB amplified (1 case both split and amplified), and 8 FISH negative) using the Covaris extraction kit. Target enriched cDNA libraries were prepared using the Archer FusionPlex kit and sequenced on the Illumina NextSeq 550. We demonstrate that the age of the specimen, quality of RNA, and sequencing metrics are important for fusion detection. Fusions were identified in 20 of 21 cases less than 2 years old, and TFE3/TFEB rearrangements were detected in all cases with Fusion QC ≥ 100. The assay identified intrachromosomal inversions in two cases (TFE3-RBM10 and NONO-TFE3), usually difficult to identify by FISH assays. TFEB mRNA expression and the TFEB/TFE3 mRNA expression ratio were significantly higher in RCCs with TFEB fusion and TFEB gene amplification compared to tumors without TFEB fusion or amplification. A cutoff TFEB/TFE3 ratio of 0.5 resulted in 97.3% concordance to FISH results with no false negatives. Our study demonstrates that the FusionPlex assay successfully identifies TFE3 and TFEB fusions including intrachromosomal inversions. Age of the specimen and certain sequencing metrics are important for successful fusion detection. Furthermore, mRNA expression levels may be used for predicting cases harboring TFEB amplification, thereby streamlining testing. This assay enables accurate molecular detection of multiple subtypes of MiT-RCCs in a convenient workflow.

Poroid adnexal skin tumors with YAP1 fusions exhibit similar histopathologic features: A series of six YAP1-rearranged adnexal skin tumors.

BACKGROUND: Adnexal skin tumors are diagnostically challenging with few known molecular signatures. Recently, however, YAP1-MAML2 and YAP1-NUTM1 fusions were identified in poroid adnexal skin tumors. METHODS: Herein, we subjected eight poroid adnexal skin tumors (three poromas and five porocarcinomas) to fusion gene analysis by whole transcriptome sequencing and next-generation DNA sequencing analysis. RESULTS: YAP1 fusions were identified in six cases. YAP1-NUTM1 fusions were identified in two poromas and three porocarcinomas. A single case of porocarcinoma harbored a YAP1-MAML2 fusion. Two cases were negative for gene fusion. All cases that harbored YAP1-NUTM1 fusions showed nuclear protein in testis (NUT) expression by immunohistochemistry, with NUT being negative in the YAP1-MAML2-positive case. In this case series, we provide a detailed histopathologic description of six YAP1-fused poroid skin tumors, which we show harbor reproducible histopathologic features, to include broad, bulbous tumor tongues with admixtures of basaloid, poroid cells punctuated by squamatized cuticles and ductules, with uniform tumor nuclei featuring frequent grooves and pseudonuclear inclusions. CONCLUSIONS: Awareness of the characteristic histopathologic features of YAP1-fused poroid adnexal skin tumor is a step toward a more reproducible classification of adnexal skin tumors as well as a step toward targeted therapy for metastatic and/or unresectable examples of this poroid group of neoplasms.

Cerebral Invasive Aspergillosis in a Case of Chronic Lymphocytic Leukemia with Bruton Tyrosine Kinase Inhibitor.

Bruton tyrosine kinase (BTK) inhibitors have become an important therapy for untreated and previously treated patients with chronic lymphocytic leukemia (CLL). Despite improved outcomes, rare adverse events, such as invasive fungal infections, have been reported with the use of first-generation BTK inhibitors. Invasive fungal infections carry a high morbidity and mortality risk. There have been several case reports describing the association between aspergillosis and ibrutinib treatment, but none with acalabrutinib, to our knowledge. In this case report, we describe a patient with CLL who developed an intracranial Aspergillus fumigatus infection while receiving acalabrutinib.

Acute Myeloid Leukemia Case Harboring Unusual FLT3 Variant: Somatic vs Germline?

FLT3 mutations are considered a prognostic and predictive marker. Here we report on a patient with a rare FLT3 germline variant in the context of relapsed acute myeloid leukemia (AML). A female patient aged 57 years presented with AML with mutations in the IDH2, ASXL1, and DNMT3A genes. She underwent allogenic hematopoietic stem cell transplant but relapsed 2 years posttransplant. Targeted next generation sequencing identified a new missense variant in the FLT3 tyrosine kinase domain c.2440G > T (p.A814S). The treating team considered the possibility of patient eligibility for an FLT3 inhibitor. Because both somatic and germline mutations can be identified in tumor tissue with high-throughput sequencing, it becomes important to distinguish the origin of these alterations when possible-especially, in this challenging case, to define the treatment modality. Simultaneous tumor/germline sequencing allows for the identification of rare germline mutations and may help in determining their significance in the pathogenesis of disease.

Molecular Pathology of Colorectal Cancer.

Colorectal cancer (CRC) is the third most commonly diagnosed cancer. This review gives an overview of the current knowledge of molecular mechanisms of colorectal carcinogenesis and the role of molecular testing in the management of CRC. The majority of CRCs arise from precursor lesions such as adenoma, transforming to adenocarcinoma. Three molecular carcinogenesis pathways have been identified; (1) chromosomal instability, (2) microsatellite instability (MSI), and (3) CpG island methylator phenotype, each account for ~85%, 15%, and 17%, respectively. Evaluation of MSI status, extended RAS mutation analysis, and BRAF mutation analysis are recommended by the guideline published by joint effort from professional societies. MSI testing is important for identification of Lynch syndrome patients and prognostic and predictive markers. Extended RAS testing is an important predictive marker for antiepidermal growth factor receptor therapy. BRAF p.V600 mutation status can be used as prognostic marker, but not predictive marker for antiepidermal growth factor receptor therapies. Emerging technologies utilizing high throughput sequencing have introduced novel biomarkers and testing strategies. Tumor mutation burden predicts immunotherapy response in addition to MSI status. Liquid biopsy can be utilized when adequate tissue sample is not available or for monitoring therapy response. However, assay standardization and guidelines and recommendations for utilization of these assay will be needed. The advancement in CRC research and technologies will allow better prognostication and therapy stratification for the management of patients with CRCs.

Clear cell papillary renal cell carcinoma: molecular profile and virtual karyotype.

Clear cell papillary renal cell carcinoma (CCP-RCC) is a recently recognized tumor that shares morphologic features of both clear cell renal cell carcinoma and papillary renal cell carcinoma but behaves in a more indolent fashion. To date, there is little molecular information available on CCP-RCC. DNA was extracted from formalin-fixed, paraffin-embedded tissue blocks of 22 cases of CCP-RCC at the University of Alabama at Birmingham. Targeted next-generation sequencing and single-nucleotide polymorphism array were performed on all cases. Next-generation sequencing analysis found 30 somatic variants across 63.3% of cases. Seventeen variants (56.7%) were predicted to be deleterious or possibly/probably damaging. Single-nucleotide polymorphism array analysis found copy number abnormalities and/or loss of heterozygosity in 22.7% of cases. We analyzed the genetic characteristics of a group of CCP-RCCs cases and found them to be genetically different from one another. Some cases were genetically similar to clear cell renal cell carcinoma.

Effects of Improved DNA Integrity by Punch From Tissue Blocks as Compared to Pinpoint Extraction From Unstained Slides on Next-Generation Sequencing Quality Metrics.

OBJECTIVES: To compare the effects of two methods of formalin-fixed paraffin-embedded (FFPE) tissue harvesting on DNA quality and next-generation sequencing (NGS) quality metrics. METHODS: DNA integrity number (DIN) and NGS quality metrics resulting from DNA extraction and sequencing of 199 sequential samples harvested via the Pinpoint Slide DNA Isolation System and the punch method were compared. RESULTS: DNA extracted from FFPE tissue punches had higher DIN than that extracted from Pinpoint samples (mean ± SD, 6.18 ± 0.83 vs 5.09 ± 0.91; P < .0001), indicating less degradation. Lower DIN correlated with lower-quality metrics of NGS, that is lower percentage of unique on-target reads, average depth of coverage, and percentage of positions with coverage depth greater than or equal to 100×, 400×, and 1,000×. CONCLUSIONS: Our study demonstrated methods to harvest tissue from FFPE blocks may affect quality of DNA, which in turn has an effect on other NGS quality metrics.

Adamantinoma-Like Ewing Sarcoma of the Thyroid: A Case Report and Review of the Literature.

Currently considered a variant of Ewing sarcoma, adamantinoma-like Ewing sarcoma is a rare malignancy that shows classic Ewing sarcoma-associated gene fusions but also epithelial differentiation. Here we present the 6th reported case of adamantinoma-like Ewing sarcoma involving the thyroid gland. Sections of the thyroid tumor from a 20-year old woman showed sheets, lobules and trabeculae of primitive, uniform, small round blue cells that diffusely expressed pankeratin, p40 and CD99. Fluorescent in situ hybridization revealed an EWSR1 gene rearrangement and an EWSR1-FLI1 fusion was detected by RT-PCR. Neck lymph nodes were not involved, and the patient was treated with a Ewing sarcoma chemotherapy protocol and radiation and is disease free 7 months after surgery. The unusual histology and immunohistochemical profile of adamantinoma-like Ewing sarcoma makes diagnosis and classification very challenging. We also present a literature review of adamantinoma-like Ewing sarcoma involving the thyroid.

NUTM1-rearranged neoplasia: a multi-institution experience yields novel fusion partners and expands the histologic spectrum.

Poorly differentiated neoplasms lacking characteristic histopathologic features represent a significant challenge to the pathologist for diagnostic classification. Classically, NUT carcinoma (previously NUT midline carcinoma) is poorly differentiated but typically exhibits variable degrees of squamous differentiation. Diagnosis is genetically defined by NUTM1 rearrangement, usually with BRD4 as the fusion partner. In this multi-institutional next-generation sequencing and fluorescence in situ hybridization study, 26 new NUTM1-rearranged neoplasms are reported, including 20 NUT carcinomas, 4 sarcomas, and 2 tumors of an uncertain lineage. NUTM1 fusion partners were available in 24 of 26 cases. BRD4 was the fusion partner in 18/24 (75%) cases, NSD3 in 2/24 cases (8.3%), and BRD3 in 1/24 (4.2%) cases. Two novel fusion partners were identified: MGA in two sarcomas (myxoid spindle cell sarcoma and undifferentiated sarcoma) (2/24 cases 8.3%) and MXD4 in a round cell sarcoma in the cecum (1/24 cases 4.2%). Eleven cases tested for NUT immunoexpression were all positive, including the MGA and MXD4-rearranged tumors. Our results confirm that NUTM1 gene rearrangements are found outside the classic clinicopathological setting of NUT carcinoma. In addition, as novel fusion partners like MGA and MXD4 may not be susceptible to targeted therapy with bromodomain inhibitors, detecting the NUTM1 rearrangement may not be enough, and identifying the specific fusion partner may become necessary. Studies to elucidate the mechanism of tumorigenesis of novel fusion partners are needed.