Platelet clumping is a common laboratory phenomenon that complicates or precludes reporting of platelet count. It is often, but not always, a phenomenon commonly caused by the anticoagulant EDTA. Herein, we discuss a case of a 14-year-old girl who was found to have platelet clumping and discuss the work-up she underwent to investigate her pseudothrombocytopenia.

Myoepithelial carcinomas (MC) represent aggressive tumors that occur in a myriad of ages and anatomic locations. The rarity and histologic similarity with other tumors make them difficult to diagnosis. We report an extremely rare case of a right ventricular outflow tract mass identified to be an intracardiac MC in a 4-month-old male infant. Pathology revealed an EWS-KLF15 translocation. Treatment included gross total resection and intensive chemotherapy. Recurrent cardiac mass with brain metastasis was seen 16 months after primary diagnosis. We describe the rarity of intracardiac MC in pediatric patients and the challenges encountered in the multimodal management of this patient.

Objectives Acute myeloid leukemia (AML) with t(8;16)(p11;p13) abnormalities is a rare, aggressive, and diagnostically challenging subtype that results in KAT6A-CREBBP gene fusion. Methods To investigate their immunophenotype and genomic features, we identified 5 cases of AML with t(8;16) through a retrospective review of the databases at Northwestern Memorial Hospital in Chicago, IL, and Washington University Medical Center, in St Louis, MO. Results In all, 4 of 5 cases were therapy related and 1 was possibly therapy related. The leukemic blasts showed distinctive features, including bright CD45 expression and remarkably high side scatter that overlapped with maturing myeloid elements, making the blasts difficult to identify on initial examination. They were positive for CD13, CD33, and CD64 and negative for CD34 and CD117. Next-generation sequencing profiling of 4 cases revealed pathogenic ASXL1 (2 cases), FLT3-tyrosine kinase domain (TKD) mutations (2 cases), and other pathogenic mutations. In 3 patients, t(8;16) was the sole cytogenetic abnormality; additional aberrations were found in 2 patients. Single nucleotide polymorphism microarray revealed 1 case with 7q deletion as a secondary clone. Conclusions Our data highlight the distinctive immunophenotypic profile of AML with t(8;16), which, along with its unique morphology, often presents a diagnostic challenge. We showed that mutations of either ASXL1 or FLT3-TKD are seen in most cases of this leukemia.

Editor's Note.-RadioGraphics continues to publish radiologic-pathologic case material selected from the American Institute for Radiologic Pathology (AIRP) "best case" presentations. The AIRP conducts a 4-week Radiologic Pathology Correlation Course, which is offered five times per year. On the penultimate day of the course, the best case presentation is held at the American Film Institute Silver Theater and Cultural Center in Silver Spring, Md. The AIRP faculty identifies the best cases, from each organ system, brought by the resident attendees. One or more of the best cases from each of the five courses are then solicited for publication in RadioGraphics. These cases emphasize the importance of radiologic-pathologic correlation in the imaging evaluation and diagnosis of diseases encountered at the institute and its predecessor, the Armed Forces Institute of Pathology (AFIP).

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