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Pediatric Epstein-Barr virus-negative monomorphic post solid organ transplant lymphoproliferative disorder [EBV(-)M-PTLD] comprises approximately 10% of M-PTLD. No large multi-institutional pediatric-specific reports on treatment and outcome are available.A multi-institutional retrospective review of solid organ recipients diagnosed with EBV(-)M-PTLD aged ≤21 years between 2001 and 2020 in 12 centers in the United States and United Kingdom was performed, including demographics, staging, treatment, and outcomes data.Thirty-six patients were identified with EBV(-)M-PTLD. Twenty-three (63.9%) were male. Median age (range) at transplantation, diagnosis of EBV(-)M-PTLD, and interval from transplant to PTLD were 2.2 years (0.1-17), 14 years (3.0-20), and 8.5 years (0.6-18.3), respectively. Kidney (n = 17 [47.2%]) and heart (n = 13 [36.1%]) were the most commonly transplanted organs. Most were Murphy stage III (n = 25 [69.4%]). Lactate dehydrogenase was elevated in 22/34 (64.7%) and ≥2 times upper limit of normal in 11/34 (32.4%). Pathological diagnoses included diffuse large B-cell lymphoma (n = 31 [86.1%]) and B-non-Hodgkin lymphoma (B-NHL) not otherwise specified (NOS) (n = 5 [13.9%]). Of nine different regimens used, the most common were: pediatric mature B-NHL-specific regimen (n = 13 [36.1%]) and low-dose cyclophosphamide, prednisone, and rituximab (n = 9 [25%]). Median follow-up from diagnosis was 3.0 years (0.3-11.0 years). Three-year event-free survival (EFS) and overall survival (OS) were 64.8% and 79.9%, respectively. Of the seven deaths, six were from progressive disease.EFS and OS were comparable to pediatric EBV(+) PTLD, but inferior to mature B-NHL in immunocompetent pediatric patients. The wide range of therapeutic regimens used directs our work toward developing an active multi-institutional registry to design prospective studies.Pediatric Epstein-Barr virus-negative monomorphic post solid organ transplant lymphoproliferative disorders (EBV(-)M-PTLD) have comparable outcomes to EBV(+) PTLD, but are inferior to diffuse large B-cell lymphoma in immunocompetent pediatric patients. The variety of treatment regimens used highlights the need to develop a pediatric PTLD registry to prospectively evaluate outcomes. The impact of treatment regimen on relapse risk could not be assessed because of small numbers. In the intensive pediatric B-non-Hodgkin lymphoma chemoimmunotherapy group, 11 of 13 patients remain alive in complete remission after 0.6 to 11 years.

Background Kikuchi-Fujimoto disease (KFD) is a rare, benign, and self-limited disease that presents with cervical lymphadenopathy and systemic symptoms. Histologic evaluation is often necessary to differentiate KFD from other entities. Methods Electronic medical records and diagnostic material were reviewed for 14 children diagnosed with KFD and 6 children diagnosed with infectious mononucleosis (IM) from 2013-2021. Four cases of KFD were further characterized using targeted DNA-based next-generation sequencing. Results Systemic symptoms were present in 86% (n = 12/14) of KFD patients, the most common being fever. Laboratory values worrisome for malignancy included cytopenia(s) (n = 9/12), elevated ESR and/or CRP (n = 9/12), elevated ferritin (n = 7/7), and elevated LDH (n = 7/10). Histologically, lymph nodes showed characteristic necrotic foci without neutrophils surrounded by MPO+ “crescentic” histiocytes. Immunoblasts and CD123+ plasmacytoid dendritic cells (pDCs) were also increased surrounding the necrosis. IM lymph nodes showed similar features when necrosis was present but increases in pDCs were patchy and rare neutrophils were seen in the necrotic foci. Molecular analysis of 4 KFD cases did not identify pathogenic variants. Conclusion While the signs/symptoms of KFD are worrisome, there are pathologic features that help differentiate it from potential mimics. We did not identify characteristic molecular features to aid in the work-up of these cases.

NUP98 fusions c omprise a family o f rare r ecurrent a lterations i n A ML, associated w ith adverse outcomes. To define the underlying biology and clinical implications of this family of fusions, we performed comprehensive transcriptome, epigenome, and immunophenotypic profiling of 2,235 children and young adults with AML and identified 160 NUP98 rearrangements (7.2%), including 108 NUP98-NSD1 (4.8%), 32 NUP98-KDM5A (1.4%) and 20 NUP98-X cases (0.9%) with 13 different fusion partners. Fusion partners defined disease characteristics and biology; patients with NUP98-NSD1 or NUP98-KDM5A had distinct immunophenotypic, transcriptomic, and epigenomic profiles. Unlike the two most prevalent NUP98 fusions, NUP98-X variants are typically not cryptic. Furthermore, NUP98-X cases are associated with WT1 mutations, and have epigenomic profiles that resemble either NUP98- NSD1 or NUP98-KDM5A. Cooperating FLT3-ITD and WT1 mutations define NUP98-NSD1, and chromosome 13 aberrations are highly enriched in NUP98-KDM5A. Importantly, we demonstrate that NUP98 fusions portend dismal overall survival, with the noteworthy exception of patients bearing abnormal chr13.

Myeloid leukemia in children with Down syndrome (ML-DS) is associated with young age and somatic GATA1 mutations. Because of high event-free survival (EFS) and hypersensitivity of the leukemic blasts to chemotherapy, the prior Children’s Oncology Group protocol ML-DS protocol (AAML0431) reduced overall treatment intensity but lacking risk stratification, retained the high-dose cytarabine course (HD-AraC), which was highly associated with infectious morbidity. Despite high EFS of ML-DS, survival for those who relapse is rare. AAML1531 introduced therapeutic risk stratification based on the previously identified prognostic factor, measurable residual disease (MRD) at the end of the first induction course. Standard risk (SR) patients were identified by negative MRD using flow cytometry (

Natural killer (NK) cells are lymphocytes of the native immune system that play a pivotal role in host defense and immune surveillance. While the conceptual view of NK-neoplasms is evolving, little is known about the rare NK lymphoblastic leukemia (NK-LL), which remains as a provisional entity in the 2016 WHO Classification. The goal of this study is to characterize NK-LL cases and compare with other CD56 co-expressing acute leukemias. We identified 105 cases, diagnosed as NK-LL (6), CD56+ acute undifferentiated leukemia (AUL) (6), CD56+ T-lymphoblastic leukemia (T-LL) (51), and CD56+ acute myeloid leukemia (AML) (42). Compared to AUL patients, NK-LL patients were significantly younger (p = 0.021) and presented with higher white blood cell (WBC) (p = 0.037) and platelet counts (p = 0.041). Flow cytometry showed more frequent expression of cytoplasmic CD3 (cCD3, p = 0.064) and CD33, (p = 0.065), while HLA-DR was significantly absent from NK-LL (p = 0.035) compared to AUL. Compared to T-ALL, NK-LL cases showed less frequent cCD3 (p = 0.002), CD4 (p = 0.051), and CD10 expression (p = 0.06). The frequency of abnormal karyotypes was similar between NK-LL, AUL, and T-ALL. The mutational profile differed in four leukemia groups, with a significance enrichment of NOTCH1 (p = 0.002), ETV6 (p = 0.002) and JAK3 (p = 0.02) mutations in NK-LL as compared to AML. As compared to T-ALL, NK-LL cases showed a higher number of total mutations (p = 0.04) and significantly more frequent ETV6 mutations (p = 0.004). Clinical outcome data showed differences in overall survival between all four groups (p = 0.0175), but no difference in event free survival (p = 0.246). In this largest study to date, we find that that NK-LL shows clinical presentation, immunophenotypic and molecular characteristics distinct from AUL, T-ALL, and AML. Our findings suggest NK-LL is a distinct acute leukemia entity and should be considered in the clinical diagnosis of acute leukemias of ambiguous lineage.

We report a 6 month-old infant girl with t(1;11)(p32;q23), KMT2A/EPS15-rearranged B-acute lymphoblastic leukemia (B-ALL) that was refractory to traditional ALL-directed chemotherapy. Following administration of blinatumomab, she experienced lineage switch from B-ALL to acute myeloid leukemia (AML). Myeloid-directed chemotherapy resulted in clearance of AML by flow cytometry, though a residual CD19+ B-ALL population persisted (0.14%). Following bridging blinatumomab, the patient achieved B-ALL and AML remission, as measured by flow cytometry. The patient subsequently underwent allogeneic hematopoietic stem cell transplant. Unfortunately, she relapsed with CD19+ B-ALL one-month post-transplantation. Next generation sequencing study of IGH/IGL using ClonoSEQ® analysis detected 3 dominant sequences all present in her original B-ALL, lineage switched AML, and post-transplant relapsed B-ALL, though the latter showed an additional 4 sequences, three of which were present at low abundance in the original diagnostic sample. The presence of the same clones throughout her disease course suggests cellular reprogramming and differentiation following chemotherapy and immunotherapy. This is the first reported case of lineage switch of B-ALL with t(1;11) and also the first report of a lineage switch case that used ClonoSEQ® to define the clonality of the original B-ALL, lineage switched AML, and relapsed B-ALL.

We describe a unique case of focal nodular hyperplasia (FNH) in a 6-month-old-girl with elevated alpha-fetoprotein (AFP). Given the patient's age and elevated AFP, a diagnosis of hepatoblastoma was presumed. However, the histopathologic assessment of the lesion was typical for focal nodular hyperplasia. This was further corroborated using hepatobiliary contrast agent to exclude the possibility of a collision or a composite liver tumor.

Objectives Compare the morphologic, laboratory, and clinical features of asymptomatic and symptomatic Castleman disease in the pediatric population. Methods We reviewed clinical records and histopathology of patients with Castleman disease from 2 pediatric institutions. Results Of 39 patients with pediatric Castleman disease, 37 had unicentric disease, all classified with the hyaline vascular variant of Castleman disease, 8 of which were clinically symptomatic. These 8 patients demonstrated abnormal laboratory findings, including microcytic anemia, elevated erythrocyte sedimentation rate and C-reactive protein, and hypoalbuminemia. In addition, histopathologic evaluation showed that the 8 symptomatic cases had more hyperplastic germinal centers, fewer atrophic or regressed germinal centers, fewer mantle zones containing multiple germinal centers, reduced “onion skinning” of mantle zones, and fewer “lollipop” formations compared with the asymptomatic cases. Conclusions This series of pediatric Castleman disease showed that lymph nodes from asymptomatic patients generally demonstrated the more classic hyaline vascular histology, whereas those with symptoms could lack or have only focal classic findings. As such, reactive lymph nodes with subtle Castleman-like features should prompt clinical correlation to ensure proper diagnosis.

Post-transplant lymphoproliferative disorders (PTLD) are diseases occurring in immunocompromised patients after hematopoietic stem cell transplantation (HCT) or solid organ transplantation (SOT). Although PTLD occurs rarely, it may be associated with poor outcomes. In most cases, PTLD is driven by Epstein-Barr virus (EBV) infection. Few studies have investigated the mutational landscape and gene expression profile of PTLD. In our study, we performed targeted deep sequencing and RNA-sequencing (RNA-Seq) on 16 cases of florid follicular hyperplasia (FFH) type PTLD and 15 cases of other PTLD types that include: ten monomorphic (M-PTLD), three polymorphic (P-PTLD), and two classic Hodgkin lymphoma type PTLDs (CHL-PTLD). Our study identified recurrent mutations in JAK3 in five of 15 PTLD cases and one of 16 FFH-PTLD cases, as well as 16 other genes that were mutated in M-PTLD, P-PTLD, CHL-PTLD and FFH-PTLD. Digital image analysis demonstrated significant differences in single cell area, major axis, and diameter when comparing cases of M-PTLD and P-PTLD to FFH-PTLD. No morphometric relationship was identified with regards to a specific genetic mutation. Our findings suggest that immune regulatory pathways play an essential role in PTLD, with the JAK/STAT pathway affected in many PTLDs.

A previously healthy 8-month-old female infant presenting with lethargy and bilateral eye redness and cloudiness had bilateral hypopyon uveitis, which persisted despite topical steroids. Cytology of the anterior chamber and cerebrospinal fluid and flow cytometry of cerebrospinal fluid revealed malignant cells consistent with acute monocytic leukemia. Bone marrow aspirates and biopsies showed no evidence of disease. She was treated with systemic and intrathecal chemotherapy, with subsequent remission and resolution of pseudo-hypopyon. Anterior chamber involvement is a rare presentation of acute myeloid leukemia and may indicate concurrent central nervous system involvement. This has important therapeutic implications, because additional treatment modalities such as intrathecal chemotherapy, local chemotherapy, and ocular radiation may be required to overcome the “pharmacologic sanctuary” created by the blood–ocular barrier. [ J Pediatr Ophthalmol Strabismus . 2021;58(5):e30–e33.]

Rosai-Dorfman disease (RDD) is an uncommon disorder, characterized by an atypical expansion of histiocytes which classically shows emperipolesis and immunoreactivity with S-100 protein. RDD affects the lymph nodes as well as extranodal sites; however, RDD of the breast is exceptionally rare. Herein, we describe the histopathologic features of 22 cases of RDD occurring in the breast, with an emphasis on the differential diagnosis. All cases were notable for an exuberant lymphocytic infiltrate with and without germinal center formation, and the majority (19/22) showed numerous plasma cells: 5 to 132/high-power field (HPF). IgG and IgG4 immunohistochemical stains were available for 13 cases; in no instance were criteria for IgG4-related sclerosing disease met, though in a single case the IgG4/IgG ratio was increased to 25%. Sclerosis was present in the majority of cases (18/22), and was frequently prominent. RDD cells showing emperipolesis were present in all cases (22/22), and ranged from rare (1/50 HPF) to numerous (50/50 HPF). Two of the cases in our series were initially misdiagnosed as inflammatory myofibroblastic tumor and plasma cell mastitis with granulomatous inflammation. As emperipolesis can be indistinct, the presence of stromal fibrosis and a prominent lymphoplasmacytic inflammatory infiltrate should prompt a careful search for the characteristic histiocytes, which can be aided by the use of S-100 immunohistochemistry.

Background Antitumor necrosis alpha (TNFα) therapy is often used in the management of patients with inflammatory bowel disease (IBD) and may have effects on lymphoid tissue architecture and function. The goal of our study was to characterize the effects of TNFα inhibitors on mesenteric lymph node and mucosa-associated lymphoid tissue in patients with IBD. Methods We examined lymphoid tissue morphology in IBD patients treated with TNFα inhibitors compared to untreated controls. Intestinal resections from 19 patients (10 anti-TNFα treated and 9 controls) were reviewed. Immunohistochemistry for CD21, CD20, and CD3 was performed on ileocecal valve lymphoid tissue and mesenteric lymph nodes from the resection specimens to assess follicular architecture. Results Relative to control groups, TNFα-treated groups showed less preserved germinal center architecture, evidenced by lower overall semiquantitative scores for follicular architecture. Likewise, the percentage of secondary follicles to total follicles was decreased in patients treated with TNFα blockade. Conclusions Our results suggest that TNFα inhibitors may play a role in disruption of lymphoid germinal center architecture in patients with IBD. Awareness of this disrupted lymphoid morphology when examining histologic sections from patients with IBD treated with TNFα inhibitors may prevent unnecessary studies to exclude a lymphoproliferative disorder.

Germline mutations in RUNX1 result in autosomal dominant familial platelet disorder with associated myeloid malignancy (FPDMM). To characterize the hematopathologic features associated with a germline RUNX1 mutation, we reviewed a total of 42 bone marrow aspirates from 14 FPDMM patients, including 24 cases with no cytogenetic clonal abnormalities, and 18 with clonal karyotypes or leukemia. We found that all aspirate smears had ≥10% atypical megakaryocytes, predominantly characterized by small forms with hypolobated and eccentric nuclei, and forms with high nuclear-to-cytoplasmic ratios. Core biopsies showed variable cellularity and variable numbers of megakaryocytes with similar features to those in the aspirates. Granulocytic and/or erythroid dysplasia (≥10% cells per lineage) were present infrequently. Megakaryocytes with separate nuclear lobes were increased in patients with myelodysplastic syndrome (MDS) and acute leukemia. Comparison to an immune thrombocytopenic purpura cohort confirms increased megakaryocytes with hypolobated eccentric nuclei in FPDMM patients. As such, patients with FPDMM often have atypical megakaryocytes with small hypolobated and eccentric nuclei even in the absence of clonal cytogenetic abnormalities; these findings are related to the underlying RUNX1 germline mutation and not diagnostic of MDS. Isolated megakaryocytic dysplasia in patients with unexplained thrombocytopenia should raise the possibility of an underlying germline RUNX1 mutation.

Chimeric antigen receptor (CAR) T-cell toxicities resembling hemophagocytic lymphohistiocytosis (HLH) occur in a subset of patients with cytokine release syndrome (CRS). As a variant of conventional CRS, a comprehensive characterization of CAR T-cell–associated HLH (carHLH) and investigations into associated risk factors are lacking. In the context of 59 patients infused with CD22 CAR T cells where a substantial proportion developed carHLH, we comprehensively describe the manifestations and timing of carHLH as a CRS variant and explore factors associated with this clinical profile. Among 52 subjects with CRS, 21 (40.4%) developed carHLH. Clinical features of carHLH included hyperferritinemia, hypertriglyceridemia, hypofibrinogenemia, coagulopathy, hepatic transaminitis, hyperbilirubinemia, severe neutropenia, elevated lactate dehydrogenase, and occasionally hemophagocytosis. Development of carHLH was associated with preinfusion natural killer(NK) cell lymphopenia and higher bone marrow T-cell:NK cell ratio, which was further amplified with CAR T-cell expansion. Following CRS, more robust CAR T-cell and CD8 T-cell expansion in concert with pronounced NK cell lymphopenia amplified preinfusion differences in those with carHLH without evidence for defects in NK cell mediated cytotoxicity. CarHLH was further characterized by persistent elevation of HLH-associated inflammatory cytokines, which contrasted with declining levels in those without carHLH. In the setting of CAR T-cell mediated expansion, clinical manifestations and immunophenotypic profiling in those with carHLH overlap with features of secondary HLH, prompting consideration of an alternative framework for identification and management of this toxicity profile to optimize outcomes following CAR T-cell infusion.

We report a 6 month-old infant girl with t(1;11)(p32;q23)

Natural killer (NK) cells are lymphocytes of the native immune system that play a pivotal role in host defense and immune surveillance. While the conceptual view of NK-neoplasms is evolving, little is known about the rare NK lymphoblastic leukemia (NK-LL), which remains as a provisional entity in the 2016 WHO Classification. The goal of this study is to characterize NK-LL cases and compare with other CD56 co-expressing acute leukemias. We identified 105 cases, diagnosed as NK-LL (6), CD56+ acute undifferentiated leukemia (AUL) (6), CD56+ T-lymphoblastic leukemia (T-LL) (51), and CD56+ acute myeloid leukemia (AML) (42). Compared to AUL patients, NK-LL patients were significantly younger (p = 0.021) and presented with higher white blood cell (WBC) (p = 0.037) and platelet counts (p = 0.041). Flow cytometry showed more frequent expression of cytoplasmic CD3 (cCD3, p = 0.064) and CD33, (p = 0.065), while HLA-DR was significantly absent from NK-LL (p = 0.035) compared to AUL. Compared to T-ALL, NK-LL cases showed less frequent cCD3 (p = 0.002), CD4 (p = 0.051), and CD10 expression (p = 0.06). The frequency of abnormal karyotypes was similar between NK-LL, AUL, and T-ALL. The mutational profile differed in four leukemia groups, with a significance enrichment of NOTCH1 (p = 0.002), ETV6 (p = 0.002) and JAK3 (p = 0.02) mutations in NK-LL as compared to AML. As compared to T-ALL, NK-LL cases showed a higher number of total mutations (p = 0.04) and significantly more frequent ETV6 mutations (p = 0.004). Clinical outcome data showed differences in overall survival between all four groups (p = 0.0175), but no difference in event free survival (p = 0.246). In this largest study to date, we find that that NK-LL shows clinical presentation, immunophenotypic and molecular characteristics distinct from AUL, T-ALL, and AML. Our findings suggest NK-LL is a distinct acute leukemia entity and should be considered in the clinical diagnosis of acute leukemias of ambiguous lineage.

Acute erythroid leukemia (AEL) is a rare subtype of acute myeloid leukemia (AML) primarily affecting older adults and was previously classified into erythroid/myeloid and pure erythroid subtypes. In this pediatric AEL study, we evaluated morphologic, immunophenotypic, cytogenetic, molecular, and clinical data of 24 (1.2%) cases from all cases undergoing central pathology review in Children’s Oncology Group trials AAML0531 and AAML1031. Of 24 cases, 5 had a pure erythroid phenotype, and 19 had an erythroid/myeloid phenotype. NUP98 fusions were highly enriched in patients with AEL, occurring in 7 of 22 cases for which molecular data were available (31.8% vs 6.7% in other AML subtypes). Of 5 cases of pure erythroid leukemias (PELs), 3 had NUP98 fusions, and 4 had complex karyotypes. Erythroid/myeloid leukemias were reclassified by using the 2017 World Health Organization hematopathology classification as: myelodysplastic syndrome (MDS) with excess blasts-1 (n = 3), MDS with excess blasts-2 (n = 7), AML (nonerythroid, n = 5), and unknown MDS/AML (n = 4); the 5 cases of nonerythroid AML included 1 with an NUP98–NSD1 fusion, 2 with myelodysplasia-related changes, and 1 with a complex karyotype. Three cases of MDS with excess blasts-2 also had NUP98 rearrangements. WT1 mutations were present in 5 of 14 cases, all erythroid/myeloid leukemia. Outcomes assessment revealed statistically poorer overall survival (5-year, 20% ± 36% vs 66% ± 23%; P = .004) and event-free survival (5-year, 20% ± 36% vs 46% ± 23%; P = .019) for those with PEL than those with erythroid/myeloid leukemia. Our study supports that AEL is a morphologically and genetically heterogeneous entity that is enriched in NUP98 fusions, with the pure erythroid subtype associated with particularly adverse outcomes.

Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening syndrome that occurs secondary to severe systemic immune activation.1 Cytotoxic T-cell proliferation leads to increased cytokine production and activation of tissue resident macrophages. Ultimately, multi-system end organ damage caused by massive inflammation may lead to a fatal outcome without timely diagnosis and initiation of appropriate therapy.2 Hemophagocytic lymphohistiocytosis affects patients of all ages and occurs as an inherited disease, or secondarily in the setting of predisposing conditions that alter the normal immune response. The inherited form of the disease presents in early childhood and is associated with homozygous mutations in genes involved in CD8+ T-cell- and NK-cell-mediated immunity.3 These genetic forms of HLH are uniformly fatal without hematopoietic cell transplant or gene therapy. Secondary HLH may occur sporadically in healthy individuals, but is more often encountered in patients with hematologic malignancy, autoimmune disease, and iatrogenic immunosuppression. Virtually all cases are thought to require an infectious or noninfectious trigger to initiate the aberrant immune response, regardless of the underlying immune dysfunction.4–7 Hemophagocytic lymphohistiocytosis presents abruptly over a period of several days to weeks with a consistent pattern of fever, pancytopenia, and splenomegaly. Common laboratory abnormalities include hyperferritinemia, hypofibrinogenemia, hypertriglyceridemia, elevated soluble IL-2 receptor, and abnormal liver func tion tests.1 The most widely used diagnostic criteria for HLH were developed for inclusion in the HLH-2004 trial which requires genetic evidence of a mutation associated with HLH or fulfillment of 5 of 8 clinical criteria including fever, splenomegaly, bicytopenia, hypertriglyceridemia or hypofibrinogenemia, evidence of hemophagocytosis in bone marrow or other tissues, low or absent NK-cell activity, elevated ferritin, and elevated soluble IL-2 receptor.3 Although not validated for adults, these HLH-2004 criteria are broadly applied in patients of all ages. Pathologists play a critical role in the diagnostic workup of patients suspected of having HLH. Bone marrow examination is performed to evaluate for hemophagocytosis, identify underlying malignancy, and exclude benign or neoplastic mimics. The presence of hemophagocytosis in the marrow fulfills one of the HLH-2004 diagnostic criteria; however, no accepted diagnostic threshold or reporting guidelines have been established. The lack of evidence-based guidelines leads to considerable uncertainty among pathologists as to what degree of hemophagocytosis is sufficient to satisfy this criterion. Adding to the challenge is that hemophagocytosis is not specific to the diagnosis of HLH in the absence of other clinical features of the disease. Rare erythrophagocytosis is commonly seen in bone marrow aspirates and increased hemophagocytosis may be encountered in the setting of sepsis, blood transfusions, hematopoietic transplantation, chemotherapy, and myelodysplastic syndrome.8–11 Given the lack of a defined threshold to fulfill the criterion for diagnosis of HLH, we designed this retrospective study to interrogate whether quantitative or qualitative morphological features of hemophagocytosis in bone marrow aspirates are predictive of the eventual diagnosis of HLH. We identified a cohort of patients presenting with clinical characteristics that were of concern for HLH and their aspirates were examined blindly. Hemophagocytes were enumerated per 1000 nucleated cells according to the lineage of their ingested hematopoietic contents [mature red blood cells (RBCs), nucleated RBCs (nRBCs), granulocytes, and lymphocytes] (Figure 1). In addition to quantitative features, we evaluated a binary morphological feature, the presence of multiple nucleated cells within a single hemophagocyte, as a possible predictive characteristic of HLH. Open in a separate window Figure 1. Examples of hemophagocytosis in patients with hemophagocytic lymphohistiocytosis (HLH). (A) Histiocytes in patients with HLH often display rounded contour with cytoplasmic projections. (B-D) Hemophagocytes with a single ingested mature red blood cell (RBC), nucleated RBC progenitor, and granulocyte, respectively. Hematopoietic progenitor cells (HPCs) often contain single nucleated hematopoietic cells in addition to multiple mature RBCs (E); however, the presence of multiple nucleated cells within the cytoplasm of a single HPC (F and G) is highly predictive of the diagnosis of HLH. (H) An example of a histiocyte with degenerating nuclear debris, indistinct cytoplasmic contour, and equivocal intracytoplasmic nucleated RBCs that we do not consider to be a definite hemophagocyte.

Background Isolated intraspinal neurosarcoidosis is a rare clinical entity, with most reports describing intramedullary involvement in adults. Case Description We detail the case of a 9-year-old girl with rapid-onset compressive myelopathy secondary to a thoracic epidural lesion. Although pathologic diagnosis was challenging, a presumptive diagnosis of isolated extradural neurosarcoidosis was made in light of the patient's investigations and dramatic response to corticosteroids. Conclusions Although less likely than neoplasia, rheumatologic processes such as inflammatory granulomatous disease warrant consideration in similar cases.

Myeloid sarcomas of the oral cavity are exceedingly rare. This report describes a recent case, and reviews the literature. This case report serves three purposes: 1) to demonstrate that the use of an intraoral biopsy can diagnose severe systemic disease; 2) to remind practitioners to be cognizant of less common diagnoses in the differential diagnosis of facial swelling; and 3) to contribute a case of myeloid sarcoma that was confirmed by flow cytometry to the published data.

Purpose: The aim of this paper is to describe a case of relapsed pediatric acute lymphoblastic leukemia (ALL) presenting as a rapidly progressive subretinal infiltrate, as diagnosed by ultrasound-guided fine needle aspiration (FNA). Methods: We conducted a clinical pathological retrospective chart review. Results: Eleven months after documented remission of T-cell ALL while on maintenance therapy, this 17-year-old patient presented with acute open angle glaucoma in the right eye. B-scan ultrasonography suggested total retinal detachment. Eight weeks later, based on routine cerebrospinal fluid analysis, the patient was diagnosed with central nervous system relapse of T-cell ALL. Repeat B-scan 1 week later showed a new hyperechoic subretinal mass. FNA of the mass confirmed leukemic infiltrate. The involved eye was enucleated, demonstrating leukemic cells throughout the subretinal space, choroid, and the optic nerve. Following hematopoietic stem cell transplant, the patient continues to maintain bone marrow remission 5 months after enucleation without involvement in the opposite eye. Conclusion: Retinal detachment in any patient with a history of leukemia should raise the possibility of relapse and may warrant aspiration/biopsy if other means of diagnosing relapse are inconclusive. Subretinal infiltrate may progress rapidly and prompt diagnosis is paramount to tailoring therapy and preserving vision.

Large B-cell lymphoma with IRF4 rearrangement is a provisional entity in the 2017 World Health Organization classification. In order to characterize these lymphomas in children from the United States, IRF4 fluorescence in situ hybridization and immunohistochemical stains were performed on 32 follicular (FL) and diffuse large B-cell lymphomas (DLBCL) from Children’s Oncology Group studies. Two DLBCLs (6%) had IRF4 rearrangements, one involving the ileocecal valve and another involving the tonsil and cerebrospinal fluid. Both cases had strong, diffuse IRF4/MUM1 immunohistochemical staining, which may be a pathologic clue to the diagnosis. Reclassification of these cases may have prognostic and therapeutic implications.

Germline mutations in

Hirschsprung disease (HD) is a congenital malformation resulting from the lack of migration of ganglion cells in the colon. The absence of ganglion cells in rectal suction biopsies aids in diagnosis, but evaluation of these small biopsies can be difficult. In this study, we compare the microtubule-associated protein-2 (MAP-2), calretinin, and peripherin immunohistochemical stains in 237 selected biopsies performed to rule out HD. By H&E stain, a total of 78 biopsies had ganglion cells, whereas 83 biopsies had no ganglion cells, and an additional 76 biopsies were equivocal for ganglion cells. Of the 78 biopsies with ganglion cells, MAP-2 was positive in 73 (94%), calretinin in 76 (97%), and peripherin in 78 (100%). Of the 83 biopsies with no ganglion cells, calretinin and peripherin highlighted nerve fibrils and ganglion cells, respectively, in 3 biopsies, whereas MAP-2 was positive in only 1 biopsy. Of the 76 biopsies equivocal for ganglion cells, 16 cases were positive by all 3 stains, an additional case by both calretinin and peripherin, and 2 cases by peripherin only. All of the newly positive biopsies were from patients without HD. This study demonstrates that peripherin is superior in helping to rule out HD in these small biopsies, highlighting ganglion cells in virtually all cases with ganglion cells, whereas MAP-2 and calretinin are less sensitive for identification of ganglion cells and nerve fibrils, respectively. In patients with HD, a panel using calretinin and peripherin with or without MAP-2 may be most helpful in identifying transition zones.

A major goal of neonatal medicine is to identify neonates at highest risk for morbidity and mortality. Previously, we developed PhysiScore (Saria et al., 2010), a novel tool for preterm morbidity risk prediction. We now further define links between overall individual morbidity risk, specific neonatal morbidities, and placental pathologies.102 placentas, including 38 from multiple gestations, were available from the previously defined PhysiScore cohort (gestational age ≤ 34 weeks and birth weight ≤ 2000 g). Placentas were analyzed for gross and histologic variables including maternal malperfusion, amniotic fluid infection sequence, chronic inflammation, and fetal vascular obstruction. Risk as determined by PhysiScore and recorded neonatal morbidities were tested for statistical association with placental findings.In pair-wise correlations, respiratory distress syndrome, bronchopulmonary dysplasia, acute hemodynamic instability, post-hemorrhagic hydrocephalus, culture-positive sepsis, and necrotizing enterocolitis each significantly correlated with at least one placenta histology variable. Amniotic fluid infection sequence (p = 0.039), specifically the fetal inflammatory response (p = 0.017), correlated with higher PhysiScores (greater morbidity) but was not independent of gestational age and birth weight. In multivariate analyses correlating variables with all nine morbidities, gestational age (p 0.001), placental size10th percentile (p = 0.031), full thickness perivillous fibrin deposition (p = 0.001), and amniotic fluid infection sequence (umbilical arteritis, p = 0.031; ≥2 chorionic plate vessels with vasculitis, p = 0.0125), each were significant associations.Amniotic fluid infection sequence plays a significant role in neonatal morbidity. Less neonatal morbidity was observed in older and heavier infants and those with small placental size and full thickness perivillous fibrin deposition. The combined assessment of placental gross and histologic findings together with physiologic risk evaluation may allow more precise prediction of neonatal morbidity risk soon after delivery.

AIMS Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is an aggressive neoplasm with leukaemic features and frequent skin involvement. Translocations involving the MYC locus have been recently identified as recurrent cytogenetic abnormalities in this entity. The aim of this study was to assess the clinicopathological, immunophenotypic and genetic features in MYC-rearranged BPDCN cases. METHODS AND RESULTS Pathology archives from six major institutes were queried for cases of BPDCN with 8q24 MYC translocations, and two cases were identified. A literature review identified 14 cases. Clinicopathological features, immunophenotype and cytogenetic and molecular data were reviewed. In these 16 MYC-rearranged cases, the median age at diagnosis was 70.5 years, and there was a male predominance. Whereas all cases showed marrow involvement, skin lesions (62.5%) and lymphadenopathy (50%) were variably seen. The median survival was 11 months. The median percentage of blasts in peripheral blood was 9%. All cases showed expression of CD4, with 10 of 16 being positive for CD56. HLA-DR, CD123, TCL1 and CD303 were positive in all cases tested. Cytogenetic analysis revealed a single recurrent translocation partner of MYC at 6p21 in 11 cases (69%), whereas four cases showed different MYC translocation partners (2p12, Xq24, 3p25, and 14q32). Interestingly, the group of patients with t(6;8)(p21;q24) showed an older median age at diagnosis (74 years) and a remarkably shorter median survival (3 months). CONCLUSIONS Translocations involving the 8q24 MYC locus more frequently manifest as t(6;8)(p21;q24), and, given its association with specific clinicopathological features suggesting even more aggressive behaviour, t(6;8)(p21;q24) indicate a genetically defined subgroup within BPDCN.

Objectives To evaluate the utility of flow cytometry, karyotype, and a fluorescence in situ hybridization (FISH) panel in screening children for myelodysplastic syndrome (MDS). Methods Bone marrow morphology, flow cytometry, karyotype, and FISH reports from 595 bone marrow specimens (246 patients) were analyzed. Results By morphology, 8.7% of cases demonstrated at least unilineage dysplasia and/or increased blasts. Flow cytometry identified definitive abnormalities in 2.8% of cases, all of which had abnormal morphology. Of the 42 cases (7.2%) with acquired karyotypic abnormalities, 26 had no morphologic dysplasia. With a 98.2% concordance between karyotype and MDS FISH, FISH only identified two additional cases, both with low-level (

• Early onset ( • Initial evaluation of a jaundiced infant should always include conjugated and unconjugated bilirubin levels. • Infants presenting with jaundice secondary to conjugated hyperbilirubinemia should undergo expedient evaluation for potentially life-threatening and treatable causes of cholestasis and then for other Gestational alloimmune liver disease causes.

In our recent case report, the finding of lupus erythematosus (LE) cells in a bone marrow aspirate led to the diagnosis of systemic lupus erythematosus (SLE) and appropriate treatment, although the patient was not clinically suspected to have SLE. To determine whether LE cells are present in the bone marrow aspirates of SLE patients, but overlooked in routine bone marrow morphology review, bone marrow aspirates from 30 pediatric patients (15 with SLE and 15 with other diagnoses) evaluated by rheumatologists were reviewed. LE cells were found in the bone marrow aspirates of only 1 SLE patient and none in non-SLE patients. However, hematoxylin bodies were identified in 53% (8/15) of SLE patients. Neither hematoxylin bodies nor LE cells were found in the aspirates from patients with other disorders. Three additional pediatric patients identified prospectively were found to have hematoxylin bodies in the bone marrow aspirates. Although the diagnosis was not initially suspected, 2 of the 3 patients were subsequently diagnosed with SLE. All patients with hematoxylin bodies and SLE had antinuclear antibody titers ≥1:640 with a homogeneous staining pattern. In addition, bone marrow aspirates of 9 adult patients were reviewed, and neither LE cells nor hematoxylin bodies were identified. In summary, hematoxylin bodies were present in the bone marrow aspirates of many pediatric SLE patients, while LE cells were rare. The finding of hematoxylin bodies in pediatric bone marrow aspirates is a helpful and specific diagnostic clue that may lead to the diagnosis of SLE when other clinical features are nonspecific.

Deregulation of MYC oncoprotein in cancers can result from multiple oncogenic mechanisms. Although MYC translocations define Burkitt lymphoma and MYC protein expression is a poor prognostic factor in undifferentiated neuroblastomas, the distribution of MYC protein (c-MYC) across other pediatric small round blue cell tumors (SRBCT) has not been well characterized. We undertook this study to assess MYC protein expression in a large cohort of pediatric lymphomas, sarcomas, and other SRBCT. Tissue microarrays containing 302 SRBCT were successfully evaluated by immunohistochemistry using anti-MYC clone Y69, with nuclear positivity scored as 0%, 1%–25%, 26%–50%, 51%–75%, or 76%–100%. MYC protein staining of >50% of lesional cells was identified in 60% of Burkitt lymphomas, 50% of B lymphoblastic lymphomas, 33% of T lymphoblastic lymphomas, 31% of rhabdomyosarcomas, 33% of Ewing sarcomas, and 25% of soft tissue sarcomas, not otherwise specified. Only 14% of neuroblastomas showed >50% staining, and of these, if known, MYCN was not amplified. No cases of Wilms tumor, synovial sarcoma, or desmoplastic small round cell tumor had >50% staining. Recurrences and metastases often had the same percentage of MYC staining (15/30). In conclusion, MYC protein exhibited variable expression across and within pediatric SRBCT subtypes. Overall, these findings provide a baseline for MYC expression in pediatric SRBCT and suggest that there may be multiple mechanisms of MYC upregulation in these different neoplasms.

Objectives E-cadherin, epithelial calcium-dependent cell adhesion protein, has been identified as a marker of immature erythroid precursors in recent years. However, the specificity of E-cadherin in bone marrow specimens for erythroblasts vs myeloblasts or other early hematopoietic precursors in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) has not been fully elucidated. Methods We analyzed 105 cases of AML and MDS to evaluate the specificity of E-cadherin. Results Of 84 cases of AML, including cases with megakaryocytic, erythroid, monocytic, and granulocytic differentiation, all five acute erythroleukemia cases were positive, as well as one case of megakaryoblastic leukemia that showed coexpression of glycophorin A. In addition, we demonstrate that a panel of three markers, E-cadherin, CD117, and CD34, is effective in identifying lineage-specific myeloblasts in cases of MDS where left-shifted erythroid hyperplasia may complicate morphologic assessment of myeloblasts. Conclusions In marrow specimens, E-cadherin is a useful marker for erythroid differentation.

Background Mold pathogens are a leading cause of chronic rhinosinusitis. Successful isolation of mold on culture is helpful in establishing a diagnosis and guiding therapy. Though mucolytic agents are commonly used in European countries, they are not part of everyday use in North America. In this case-control prospective study, we investigated the yield of fungal culture before and after treatment of sinus aspirates with the mucolytic agent dithiothreitol in a United States hospital. Methods Over a 5-month period during 2011–2012, 359 sinus aspirates from 294 patients with symptoms suspicious for chronic sinusitis or allergic fungal sinusitis were collected. Aspirates were cultured on fungal medium before and after treatment with dithiothreitol. Results Of the 359 pairs of cultures, 62 (17.3%) demonstrated mold growth on at least 1 of the plates, 9 (14.5%) of which grew more than 1 species of mold. A total of 75 molds were identified, 41 (54.7%) of which were successfully cultured only when the mucus was pretreated with dithiothreitol (p < 0.0001). Quantitatively, more colonies grew from dithiothreitol-treated mucus than from direct-inoculation (p < 0.0001). Conclusion This study confirms improved recovery of mold from sinus cultures after pretreatment of samples with dithiothreitol. Further studies are needed to correlate these findings with clinical outcome.

Congenital cytomegalovirus (CMV) infection may be asymptomatic until hearing loss manifests in childhood. Because diagnosis of congenital CMV requires viral detection within an infant's first 21 days of life, CMV polymerase chain reaction (PCR) on formalin-fixed, paraffin-embedded (FFPE) placental tissue provides a unique opportunity to identify congenital exposure in cases in which CMV is not initially suspected. To assess the utility of this approach, a database of all CMV cultures performed from July 2001 to March 2012 was used to identify infants in whom urine CMV cultures were obtained within 100 days of life. Corresponding placentas were then identified through the pathology database. The database was also queried to identify placentas in which CMV immunohistochemical analysis had been performed. CMV PCR was positive in FFPE placental tissue from 100% (5/5) of cases in which the first urine culture collected before the first 21 days of life was positive. Placentas from 20 infants with negative CMV urine cultures were CMV PCR negative. Interestingly, CMV was detected in 12.5% (1/8) of placentas in which the first CMV-positive urine culture was collected after the first 21 days of life. Furthermore, 4% (1/26) of placentas with chronic villitis by histology (no urine cultures available) were CMV PCR positive. In the 10 CMV PCR-positive placentas, including 3 cases of fetal demise, CMV immunohistochemistry was positive in just 6 cases. These results suggest that the confirmation of CMV exposure in utero by PCR of FFPE placental tissue provides a useful adjunct to histologic evaluation and may identify infants requiring close clinical follow-up.

Necrotizing enterocolitis (NEC) is typified by mucosal destruction, which subsequently can lead to intestinal necrosis. Prematurity, enteral feeding, and bacterial colonization are the main risk factors and, combined with other stressors, can cause increased intestinal permeability, injury, and an exaggerated inflammatory response. Heme oxygenase-1 (HO-1) mediates intestinal protection due to anti-inflammatory, antioxidative, and antiapoptotic effects of its products carbon monoxide, biliverdin, and bilirubin. This study investigates a possible role of HO-1 in the pathogenesis of NEC using a newborn mouse model. We induced NEC-like intestinal injury in 7-day-old HO-1 heterozygous (HO-1 Het, Hmox1+/-) and wild-type (Wt, Hmox1+/+) mice by gavage feeding and hypoxic exposures. Control (Con) pups of both genotypes were dam-fed. Intestines of HO-1 Het Con pups appeared predisposed to injury, with higher histological damage scores, more TUNEL-positive cells, and a significant reduction in muscularis externa thickness compared with Wt Con pups. The increase in HO activity after HO-1 induction by the substrate heme or by hypoxic stress was significantly impaired in HO-1 Het pups. After induction of intestinal injury, HO-1 Het pups displayed significantly higher NEC incidence (78 vs. 43%), mortality (83 vs. 54%), and median scores (2.5 vs. 1.5) than Wt NEC pups. PCR array analyses revealed increased expressions of IL-1β, P-selectin, matrix metallopeptidase 2, collagen type XVIII-α1, serpine 1, and others in NEC-induced HO-1 Het ileal and jejunal tissues. We conclude that a partial HO-1 deficiency promotes experimental NEC-like intestinal injury, possibly mediated by exaggerated inflammation and disruption in tissue repair.

Fibrosarcomas are rare malignant soft-tissue tumors occurring mostly in infants younger than 1 year of age. Fibrosarcomas can ulcerate and cause various complications, which could threaten a fetus in utero or a child in the early neonatal period. We report a unique case of congenital infantile fibrosarcoma of the lower leg, its treatment and pathology. The large expansive and destructive lesion was not appreciated on routine prenatal ultrasound exams at 20 and 33 weeks gestation. The newborn required immediate emergency surgical intervention after delivery to prevent death by hemorrhagic shock. Initial debulking of the tumor was performed and hemostasis was attained on the day of birth. The child was resuscitated and definitive treatment of the leg was deferred until a pathologic diagnosis was obtained. Given the extent of the fibrosarcoma, the lower leg was not salvageable and the patient received a through-the-knee amputation in the neonatal period. The patient is free of disease at 2 years of age.