Fine-needle aspiration (FNA) followed by a core-needle biopsy during general anesthesia is a method for diagnosing pediatric tumors in our Institute. To complete the diagnosis in the case of round cell sarcomas, cytology material is also used for genomic analyses, that is, karyotyping and molecular biology-derived techniques. Fifty primary Ewing sarcomas/peripheral neuroectodermal tumors (ES/PNET) in 50 patients were sampled. Cytological diagnoses were "malignant" in all cases and accurate (ES/PNET) in 46 (92%). Two (4%) cases were misdiagnosed as neuroblastoma, and two others (4%) as rhabdomyosarcoma and nephroblastoma. No suspicious or false-negative results were rendered. Karyotyping was performed in 20 (40%) cases and was interpretable in 17 cases but not in three cases. Molecular search for ES/PNET fusion transcripts were performed in all cases and were detected in 44 (88%) cases, but not in six (12%) cases. In conclusion, FNA assisted by genomic techniques is powerful methods to accurate diagnose ES/PNET.

Myxofibrosarcoma (MFS) is a well-established nosologic entity different from the myxoid variant of malignant fibrous histiocytoma. In an attempt to better define the representative cytologic criteria of MFS, we undertook a review and a reanalysis of a series of 14 cytology samples in 12 patients whose tumors were diagnosed as MFS.Using FNA technique and reviewing the original diagnoses, 11 cases were diagnosed as malignant and three as benign tumors. The cytologic diagnosis of MFS was accurate in seven cases (2 primary tumors, 4 recurrences, and 1 metastasis). Four cases were classified malignant myxoid sarcoma (1 primary and 3 recurrences), whereas three cases (2 primary and 1 recurrence) were false-negative.The smears were cell-rich in 12 cases and cell-poor in two cases. They were constantly composed of isolated and regular small spindle-shaped and stellated cells with elongated nuclei containing small inconspicuous nucleoli. Cytoplasm was pale with elongated processes. Clusters of wavy spindle-shaped cells, round cells without specific pattern, moderate cytonuclear atypia, and abundant myxoid background as well as curvilinear vascular structures were always seen. In the vast majority of cases, the cytologic distinction of MFS from other low-grade myxoid lesions is difficult. Entities such as myxoid MFH, myxoid liposarcoma (MLP), myxoid DFSP, and myxoma should be considered in the differential diagnosis. The cytological misdiagnosis is of limited clinical consequence because FNA findings suggestive of a myxoid tumor will be indicative for a surgical removal followed by the histopathological analysis.

Nuclear Protein in Testis (NUT) Midline Carcinoma (NMC) represents a recently described, uncommon, high-grade and extremely lethal malignancy mainly occurring in children and young adults. Such tumors are genetically characterized by chromosomal rearrangements of the NUT gene. Cytological description of NUT carcinoma is limited and only seven cases were reported up to date. We show here another two cases studied cytologically with molecular and immunohistochemical confirmation. In both cases smears were hypercellular and composed of isolated or clustered small to medium-sized in size with roundish and oval shape cells. Nuclei were either regular or roundish containing dusty chromatin and prominent nucleoli. Mitotic figures were prominent. Cytoplasm was scant, strongly basophilic. Cell debris, necrosis, and apoptosis were also prominent. One of the cases was studied by FISH and the second case was studied by RT-PCR and BRD4-NUT translocation was found in both cases. Moreover, the clinical evolution was aggressive in both cases with rapid fatal clinical outcome. NUT carcinomas are an underdiagnosed entity which should be taken into consideration when poorly differentiated carcinomas was diagnosed in children or young adults. Cytology material may be successfully used for morphological and molecular diagnosis. Diagn. Cytopathol. 2016;44:753-756. © 2016 Wiley Periodicals, Inc.

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