Identification of rapidly growing mycobacteria (RGM) is problematic because there are many taxonomic changes. 16S rRNA gene is commonly used to identify Mycobacterium species, but alternative gene targets have been introduced for more accurate identification. We report a rare case of a prosthetic knee infection due to Mycobacterium wolinskyi. The isolate was not identified by 16S rRNA gene sequencing alone and substantially confirmed by rpoB gene sequencing. The identification was delayed because our laboratory did not routinely identify RGM to the species level. Simultaneous sequencing of both 16S rRNA and rpoB genes will allow rapid and accurate identification of M. wolinskyi isolates.

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Biphenotypic acute leukemia (BAL) is a rare type of leukemia, comprises 4% of all acute leukemias. It is more common in adults and the clinical features, as related to marrow dysfunction, are similar to those found in other patients with acute leukemia. BAL commonly shows a dimorphic blast population with, one resembling lymphoblasts and the other resembling myeloblasts. The majority of BAL patients express B-lymphoid and myeloid markers. BAL can be diagnosed by morphologic studies and by a comprehensive panel of immunological markers, as well as cytogenetic/molecular studies, such as fluorescence in situ hybridization (FISH) and reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, its prognosis is relatively poor. We present here a 27 year-old female patient who showed lymphoblasts and myeloblasts on her marrow studies and these cells were positive for myeloid and B-lymphoid markers on the immunophenotypic studies. Chromosome analysis revealed 46,XX,t(6;19)(p23;p13.1),t(9;22)(q34;q11.2). A major (b3a2) type of BCR-ABL1 mRNA transcript was detected by RT-PCR, and a 5'ABL1 deletion was identified by FISH.

Crystal-storing histiocytosis (CSH) is a rare event observed in association with lymphoproliferative diseases, and mainly occur in plasma cell dyscrasias. It is presumed to be an intra-lysosomal accumulation of the secreted paraproteins. Crystal formation can be seen inside histiocyte-like cells with phagocytosed crystalline inclusions in the bone marrow and extramedullary sites. CSH is a rare morphological entity with poor prognostic implications and may be confused with Gaucher or pseudo-Gaucher cells. Herein we report a case of non-secretory myeloma associated with CSH showing a poor clinical course. A 79-yr-old male presenting with dizziness was evaluated in hematology department for anemia. Laboratory tests revealed Hb of 4.9 g/dL and β2-microglobulin of 21,000 ng/mL (reference range, 0-370). Presence of monoclonal protein was not detected on protein electrophoresis and immunofixation in serum and urine. However, serum free light chain assay showed an increased kappa-light chain level of 126 mg/L (reference range, 3.3-19.4) resulting in an increased kappa/lambda ratio. The bone marrow touch print showed numerous plasma cells and crystal-laden histiocytes and immunohistochemical stainings on bone marrow biopsy revealed positivity for CD38, CD56 and kappa in the plasma cells and CD68 and kappa in crystal-laden histiocytes.

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