Schafernak, Kristian

Large B-cell lymphoma with IRF4 rearrangement (LBCL-IRF4) predominantly affects children and young adults (CAYA) and presents as localized disease with excellent prognosis. Although most tumors harbor IRF4 rearrangements (IRF4-R), the existence of cryptic rearrangements has been suggested. Whether IRF4-R LBCL in adults represents the same biological entity remains unclear. To address this question, 35 CAYA patients diagnosed with LBCL-IRF4 and 7 adult (>40-year-old) LBCL with IRF4-R were investigated by an integrative molecular approach. Targeted sequencing structural variant analysis (SV-NGS) confirmed the IRF4-R in 84% of investigated cases. In CAYA, an enrichment (55% vs 29% in adults) of translocations involving IGH, with a breakpoint cluster 3' to IRF4 (EXOC2) was observed, including a cryptic insertion of IGHM-IGHJ5 into IRF4 locus. Novel translocations, IRF4::MIR142 in two CAYA (7%) and IRF4::BATF in one adult, were discovered. Whole-exome sequencing analysis identified unreported mutations in LBCL-IRF4 as YY1 and ZC3H12A (11% each). The high incidence of mutations affecting the B-cell receptor/NF-KB pathways in LBCL-IRF4 was confirmed in cases with diffuse component only. None of the CAYA tumors were classified by LymphGen tool. Adult IRF4-R LBCL showed higher levels of genetic complexity and a distinct mutational profile with mutations on KMT2D and DTX1 (43% each), and MYD88-L265P (29%), and were predicted as EZB or MCD (29% each). These differential genetic features were in line with different clinical presentations (extranodal involvement and advanced stage). In conclusion, IRF4-R architecture and mutational profile differ according to age, supporting that not all cases should be classified as LBCL-IRF4.

Abstract Lineage switch (LS), defined as the immunophenotypic transformation of acute leukemia, has emerged as a mechanism of relapse after antigen-targeted immunotherapy, which is associated with dismal outcomes. Through an international collaborative effort, we identified cases of LS after a host of antigen-targeted therapies (eg, CD19, CD22, CD38, and CD7), described how LS was diagnosed, reviewed treatment approaches, and analyzed overall outcomes for this form of postimmunotherapy relapse. Collectively, 75 cases of LS were evaluated, including 53 (70.7%) cases of B-cell acute lymphoblastic leukemia (B-ALL) transforming to acute myeloid leukemia (AML), 17 (22.7%) cases of B-ALL transforming to mixed phenotypic acute leukemia (MPAL)/acute leukemias of ambiguous lineage (ALAL), and 5 (6.7%) cases of rare LS presentation (ie, T-cell ALL to AML). An additional 10 cases with incomplete changes in immunophenotype, referred to as “lineage drift” were also described. With a primary focus on the 70 cases of LS from B-ALL to AML or MPAL/ALAL, LS emerged at a median of 1.5 months (range, 0-36.5) after immunotherapy, with 81.4% presenting with LS within the first 6 months from the most proximal immunotherapy. Although most involved KMT2A rearrangements (n = 45, 64.3%), other rare cytogenetic and/or molecular alterations were uniquely observed. Treatment outcomes were generally poor, with remission rates of <40%. The median overall survival after LS diagnosis was 4.8 months. Outcomes were similarly poor for those with rare immunophenotypes of LS or lineage drift. This global initiative robustly categorizes lineage changes after immunotherapy and, through enhanced understanding, establishes a foundation for improving outcomes of LS.

AbstractBackgroundRenal medullary carcinoma (RMC) is a diagnostically challenging, aggressive primary renal malignancy associated with abysmal survival. Delays in diagnosis contribute to most patients having diffusely metastatic disease at the time of initial presentation.MethodsWe present the case of a 13‐year‐old African American male with sickle cell trait who presented with a renal mass and hematuria. Evaluation included imaging, fluid cultures, and cytologic assessment.ResultsPatient was diagnosed with RMC based on cytologic assessment of sub‐centimeter fluid collections aspirated from the left kidney at the time of cortical biopsy for suspected renal mass. The additional fluid aspiration in conjunction with renal biopsy was an atypical but crucial step in early diagnosis.ConclusionCytomorphologic evaluation of fluid biospecimens is not currently part of the standard work‐up for patients with renal masses but, when available, can provide crucial information that reduces time to diagnosis. Prompt symptom recognition and treatment initiation may improve patient outcomes.

Background: Childhood cancer survivors and bone marrow transplant recipients treated with radiation therapy (RT) are at increased risk for subsequent thyroid cancer. However, the genetic landscape of pediatric thyroid cancer, both primary and RT-induced, remains poorly defined, as pediatric papillary thyroid carcinoma (PTC) has been understudied compared with adults and data on pediatric follicular thyroid carcinoma (FTC) are virtually nonexistent. The objective of this study was to characterize and compare the molecular profiles of pediatric RT-induced PTC and FTC cases with primary pediatric thyroid cancers. Methods: A total of 41 differentiated thyroid carcinomas (11 RT cases and 30 primary cases) from 37 patients seen at Phoenix Children's Hospital between January 1, 2010 and December 31, 2019 were evaluated by targeted next-generation sequencing and/or BRAF immunohistochemistry. Results: Eighty-six percent (6/7) of RT-PTC harbored a gene fusion (GF) compared with 56% (14/25) of primary PTC; 14% (1/7) of RT-PTC had a single-nucleotide variant (SNV; specifically, a point mutation in the DICER1 gene ) compared with 44% (11/25) of primary PTC (all of the latter had the BRAF V600E mutation). An exceedingly rare ROS1 fusion was identified in a child with RT-PTC. With respect to FTC, copy number alterations (CNAs) were seen in 75% (3/4) of RT cases compared with 40% (2/5) of primary cases. None of the RT-FTC had SNVs compared with 100% (5/5) of primary FTC. Conclusions: In children, the molecular profile of subsequent RT-induced thyroid cancers appears to differ from primary (sporadic and syndromic) cases, with a high prevalence of GFs in RT-PTC (similar to PTC occurring after the Chernobyl nuclear reactor accident) and CNAs in RT-FTC. A better understanding of the molecular mechanisms underlying these cancers may lead to more accurate diagnosis, prognosis, and treatment, as some of the genomic alterations are potentially targetable.

Abstract ALK-positive histiocytosis is a rare subtype of histiocytic neoplasm first described in 2008 in 3 infants with multisystemic disease involving the liver and hematopoietic system. This entity has subsequently been documented in case reports and series to occupy a wider clinicopathologic spectrum with recurrent KIF5B-ALK fusions. The full clinicopathologic and molecular spectra of ALK-positive histiocytosis remain, however, poorly characterized. Here, we describe the largest study of ALK-positive histiocytosis to date, with detailed clinicopathologic data of 39 cases, including 37 cases with confirmed ALK rearrangements. The clinical spectrum comprised distinct clinical phenotypic groups: infants with multisystemic disease with liver and hematopoietic involvement, as originally described (Group 1A: 6/39), other patients with multisystemic disease (Group 1B: 10/39), and patients with single-system disease (Group 2: 23/39). Nineteen patients of the entire cohort (49%) had neurologic involvement (7 and 12 from Groups 1B and 2, respectively). Histology included classic xanthogranuloma features in almost one-third of cases, whereas the majority displayed a more densely cellular, monomorphic appearance without lipidized histiocytes but sometimes more spindled or epithelioid morphology. Neoplastic histiocytes were positive for macrophage markers and often conferred strong expression of phosphorylated extracellular signal-regulated kinase, confirming MAPK pathway activation. KIF5B-ALK fusions were detected in 27 patients, whereas CLTC-ALK, TPM3-ALK, TFG-ALK, EML4-ALK, and DCTN1-ALK fusions were identified in single cases. Robust and durable responses were observed in 11/11 patients treated with ALK inhibition, 10 with neurologic involvement. This study presents the existing clinicopathologic and molecular landscape of ALK-positive histiocytosis and provides guidance for the clinical management of this emerging histiocytic entity.

Pre-B cell acute lymphoblastic leukemia (ALL) is a hematologic malignancy that arises from overproduction of immature lymphoid cells. ALL has a propensity for recurring in the bone marrow and/or extramedullary sites following complete remission. We present the case of a young male with a history of pre-B cell ALL who presented with leukemic recurrence isolated to the optic nerve. Transvitreal fine needle aspiration biopsy followed by transconjunctival optic nerve biopsy confirmed the diagnosis of ALL relapse and should be considered helpful diagnostic tools in the setting of suspected optic nerve malignancy with otherwise negative workup.

e21528 Background: Thyroid cancer is a common secondary malignancy among childhood cancer survivors who have received radiation to the head, neck and/or upper thorax. The optimal strategy for surveillance for thyroid carcinoma in childhood cancer survivors remains controversial. Current Children’s Oncology Group recommendations are limited to physical exam. The objective of this study was to determine the sensitivity and specificity of thyroid ultrasound versus neck exam by a pediatric endocrinologist in the diagnoses of thyroid cancer in a cohort of high-risk childhood cancer survivors. Methods: Medical records of childhood cancer survivors who received radiotherapy to the head, neck and/or upper thorax were reviewed. These patients were seen in a comprehensive childhood cancer survivorship clinic from 01/01/2010 to 12/31/2017. Patient populations included oncology, bone marrow transplant and brain tumor patients. Results: 226 patients received radiation to the head, neck and/or upper thorax. Of those, 129 patients were male (57%). Sixteen (7.1%) of patients developed a secondary thyroid malignancy including 4 patients previously treated for an oncological malignancy, 9 patients treated with bone marrow transplantation, and 3 patients with a CNS malignancy. Median radiation dose was 1800 cGy (range 400-5940 cGy). Time to thyroid carcinoma diagnosis occurred at a median of 12 years (range 4-19 years) from treatment with radiation. Screening ultrasounds were obtained in 146 (65%) patients while 226 (100%) had a physical exam. Two cases were identified by abnormalities on physical exam. The sensitivity of US was 100% (CI 80.6-100) compared to a sensitivity of 12.5% (CI 3.5-36) using physical exam (P < 0.0001). Screening ultrasound had a specificity of 73% (CI 65.1-80.1) while physical exam yielded a specificity of 100% (CI 98.2-100). Conclusions: Regular screening with ultrasounds provide the greatest sensitivity for detection of secondary thyroid carcinomas after head, neck and upper thorax radiation in childhood cancer survivors. If screening ultrasounds were not routinely utilized in our clinic, 14 of the 16 patients (87.5%) would have had a delay in their diagnosis of a secondary thyroid malignancy. Screening ultrasounds may lead to earlier detection of thyroid carcinomas, with the potential to decrease the need for aggressive surgery, radioiodine therapy and, ultimately, to decrease recurrence risk.

Skeletal muscle lymphoma is rare, comprising only a very small subset of lymphoma cases. There are characteristic imaging features which, if recognized, can prevent delay in diagnosis and treatment, particularly when not suspected clinically. Herein, we report two cases of skeletal muscle lymphoma with nearly identical imaging features; the first is an example of primary muscle lymphoma in a 17-year-old boy with back and thigh pain, and the second represents lymphoma recurrence in a 55-year-old man with HIV. Characteristic features seen on MRI were key in raising suspicion for the disease and helped prevent a delay in pathologic diagnosis.