Blastic Plasmacytoid Dendritic Cell Neoplasm; A Report of Three Cases.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematodermic myeloid malignancy that is known to be derived from plasmacytoid dendritic cells which are characterized by expression of CD4, CD56, and more specific markers such as CD123. Here, the authors present three cases of BPDCN diagnosed in the past two years and address different available diagnostic modalities such as morphology, immunohistochemistry, flow cytometry, and cytogenetics. Overall, we believe that although BPDCN is a rare diagnosis, it should not be left unchecked. Currently, available immunophenotyping markers are of great help, but the main clue to figure out the problem of BPDCN is clinicopathologic suspicion.

Evaluation of the CD123 Expression and FLT3 Gene Mutations in Patients with Acute Myeloid Leukemia.

BACKGROUND AND OBJECTIVE: Identification of cytogenetic and molecular changes plays an important role in acute myeloid leukemia (AML) patients. Thus, they are used in classification, prognosis and treatment of the disease. The CD123 expression and FLT3 gene mutations are also the variations that may assist in prognosis and treatment of patients with AML. METHODS: This study was performed on 76 patients as new cases of AML. The correlation between CD123 immunohistochemical (IHC) expression and FLT3 gene mutations with each other as well as morphological, immunophenotypical and cytogenetic factors was studied. RESULTS: The results represented the CD123 IHC expression in 55.3% and FLT3 gene mutations in 28.9% of cases. We found that 81.3% of patients who had FLT3/ITD gene mutations revealed IHC of CD123 expression (P=0.019). The CD123 expression against FLT3 was also correlated with monocytic differentiation in bone marrow blasts (P=0.031). There were significant correlations between IHC expression of CD123 and FLT3/ITD mutations with a high percentage of aspirated bone marrow blasts (P=0.01 and P=0.006, respectively) as well as the lack of CD34 expression in bone marrow blasts (P=0.007 and P=0.021, respectively). CONCLUSION: The CD123 IHC positive AMLs were correlated with certain pathologic features, some of which can be similar with correlations of background mutation of FLT3/ITD; According to the negative predictive value (NPV), 88.2% of CD123 IHC showed FLT3 gene mutation. In addition to its use in targeted therapy, it could be a marker to decide what molecular tests to use in the next steps.

Extragastrointestinal Stromal Tumor Presenting as Omental Cyst.

INTRODUCTION: Extragastrointestinal stromal tumors (EGIST) are rarer counterparts of gastrointestinal stromal tumors (GIST) in omentum, mesentery, and retroperitoneum. CASE REPORT: Hereby, authors present a 47-year-old man with abdominal mass whose abdominal CT scan revealed a large septated cystic mass measuring 16 cm in largest diameter. The mass was aspirated and resected by laparotomy. Pathologic examination exhibited a mesenchymal spindle cell neoplasm which was immunohistochemically reactive for CD117 and SMA. Thus, the diagnosis of extragastrointestinal stromal tumor was made. DISCUSSION: A cystic EGIST in omentum falls in the differential diagnoses of omental cystic lesions which include omental cyst, mesenteric teratoma, cystic mesothelioma, cystic spindle cell tumors, pseudomyxoma peritonei, pancreatic pseudocyst, and complicated ascites. Therefore, proper diagnosis of cystic GIST is of great importance in respect to different behavior, management, and complications in comparison to its mimickers and GI counterparts.

A Rare Case of Extramedullary T/Myeloid Mixed Phenotype Acute Leukemia with t(1;5)(q23;q33).

Mixed phenotype acute leukemia (MPAL) is a rare neoplasm which accounts for 2-5% of all leukemias and it is classified under heading of acute leukemia of ambiguous lineage in 2008 WHO classification. This patient was a 61-year-old man who presented with malaise and weakness. In physical examination there was cervical and axillary lymphadenopathy. Paraclinical evaluation revealed anemia (Hb = 10.3 g/dL, MCV = 108 fl). Histologic sections of the axillary lymph node revealed leukemic involvement with two discrete populations of cells in immunohistochemistry. One population was immunoreactive for MPO and the other showed immunostaining for CD3, CD99, and tdt. Differential count of bone marrow cells in marrow aspirate had 6% blast. Karyotype study on bone marrow culture depicted an interesting finding which was t(1;5)(q23;q33). An extensive search on literature was done for the same genetic change. A similar translocation has been mentioned in literature for other hematologic malignancies but not for same neoplasm; anyhow this translocation was an imbalanced one and led to der(5)t(1;5)(q12-25;q13-q35).