Malignant small round cell tumors are characterised by small, round, relatively undifferentiated cells. They generally include Ewing's sarcoma, peripheral neuroectodermal tumor, rhabdomyosarcoma, synovial sarcoma, non-Hodgkin's lymphoma, retinoblastoma, neuroblastoma, hepatoblastoma, and nephroblastoma or Wilms’ tumor. Other differential diagnoses of small round cell tumors include small cell osteogenic sarcoma, undifferentiated hepatoblastoma, granulocytic sarcoma, and intraabdominal desmoplastic small round cell tumor. Differential diagnosis of small round cell tumors is particularly difficult due to their undifferentiated or primitive character. Tumors that show good differentiation are generally easy to diagnose, but when a tumor is poorly differentiated, identification of the diagnostic, morphological features is difficult and therefore, no definitive diagnosis may be possible. As seen in several study reports, fine needle aspiration cytology (FNAC) has become an important modality of diagnosis for these tumors. The technique yields adequate numbers of dissociated, viable cells, making it ideally suitable for ancillary techniques. Typically, a multimodal approach is employed and the principal ancillary techniques that have been found to be useful in classification are immunohistochemistry and immunophenotyping by flow cytometry, reverse transcriptase polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), and electron microscopy. However, the recent characterization of chromosomal breakpoints and the corresponding genes involved in malignant small round cell tumors means that it is possible to use molecular genetic approaches for detection.

FCI is applicable on FNA material and complements ICC in accurate the typing of MSRCTs. This is particularly useful in advanced-stage disease, when neoadjuvant chemotherapy may be instituted promptly.

BACKGROUND: Precursor T-lymphoblastic lymphoma (T-LBL) is a rare lymphoma presenting clinically in children and adolescents with a rapidly enlarging mediastinal mass, dyspnea, and cervical lymphadenopathy requiring quick diagnosis.The objective of the current study was to report on the spectrum of cytomorphology and flow cytometric immunopheno-

We evaluated the feasibility and usefulness of reverse transcriptase-polymerase chain reaction (RT-PCR) on fine-needle aspirates for categorization of small blue round cell tumors (SBRCTs). A total of 51 cases, including 25 Ewing sarcoma/peripheral primitive neuroectodermal tumors (PNETs), 11 rhabdomyosarcomas, 13 neuroblastomas, and 2 desmoplastic small round cell tumors (DSRCTs) were analyzed. The detection of the EWS-FLI1 (20/25) and EWS-ERG (4/25) fusion transcripts resolved 24 of 25 cases of Ewing sarcoma/PNET. The PAX3/7-FKHR fusion transcript was detected in 2 of 4 cases of alveolar rhabdomyosarcoma and the EWS-WT1 transcript in both cases of DSRCT. Tyrosine hydroxylase and 3,4-dihydroxyphenylalanine (dopa) decarboxylase transcripts were demonstrated in 10 of 13 cases of neuroblastoma. In comparison, immunocytochemical analysis resolved 19 (76%) of 25 Ewing sarcomas, 9 (82%) of 11 rhabdomyosarcomas, 6 (46%) of 13 neuroblastomas, and 1 (50%) of 2 DSRCTs. Overall, RT-PCR resolved 38 (86%) of 44 vs 35 (69%) of 51 cases by immunocytochemical analysis. RT-PCR is easily applied to fine-needle aspirates of SBRCT and greatly facilitates accurate tumor typing.

BACKGROUND: Synovial sarcoma (SS) is characterized by the t(X; 18) (p11.2; q11.2) translocation resulting in the SYT-SSX fusion transcript, detectable by reverse transcriptase polymerase chain reaction (RT-PCR).

Primary Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) of the kidney is a distinct entity that can be mistaken for variety of round cell tumors. We report a rare case of ES/PNET of the kidney in a 35-year-old female patient diagnosed by fine needle aspiration cytology (FNAC) and confirmed by immunohistochemistry (IHC) and reverse-transcriptase polymerase chain reaction (RT-PCR). Ultrasound guided FNAC smears from the kidney mass showed a population of malignant small round cells with perivascular arrangement and focal rosette formation. IHC performed on the cell block, showed strong immunopositivity for CD99 (MIC2) and vimentin. Molecular analysis of the aspirate by RT-PCR confirmed the EWS-FLI type1 transcript. The application of RT-PCR on FNAC material for establishing a diagnosis of renal ES/PNET is being reported for the first time. FNAC also confirmed metastases in the right level I cervical lymph node. The utility of IHC and molecular techniques in diagnosis of such a rare case is stressed and relevant literature is discussed.

Introduction We evaluated the role of simultaneous use of multiple antibodies in flow cytometry (FCM) to detect metastatic carcinomas in effusion samples. Methods Cytological examination of 75 successive cases of effusion samples was performed. There were 48 peritoneal, 26 pleural and one pericardial fluid. Multi‐coloured FCM examination was undertaken using a cocktail of CD45, CD14 and epithelial cell adhesion molecule (EpCAM), antibodies tagged with different fluorochromes. The percentage of EpCAM positivity was calculated in the CD45 and CD14 dual negative population by selective gating. The EpCAM value was correlated with the cytological findings, follow‐up data and MOC‐31 immunostaining. Results There were 20 benign, 35 malignant and 20 atypical cases diagnosed on cytomorphology. The primary sources of carcinomas were mainly from the ovary, followed by lung, gall bladder, intestine and other areas. Out of 20 cytologically benign cases, there were two malignant cases on the final follow‐up, and EpCAM on FCM picked up all 18 benign cases and one malignant case. Out of 35 cytologically detected malignant cases, EpCAM picked up 32 malignant cases. The EpCAM detected 15/18 malignant and both benign cases out of 20 cytological atypical cases. EpCAM antibody by FCM showed 87% sensitivity, 100% specificity, 100% positive predictive value and 74% negative predictive value. Conclusion This comprehensive study highlights the potential use of multi‐coloured FCM along with cytological examination to diagnose metastatic carcinoma in effusion samples. Multi‐coloured FCM is rapid and quantitative and is helpful in atypical cases.

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