Malignant small round cell tumors represent a diagnostic challenge for cytologists and pathologists. This case series describes four cases of unusual metastasis of small round cell tumors subtypes into body cavities generating effusions in which fluid cytological examination suggested the neuroendocrine origin of the tumors. Tumor diagnosis (Ewing sarcoma/primitive neuroectodermal tumor and desmoplastic small round cell tumors) were unknown at the cytological evaluation. We can highlight the importance of the accurate analyses of body fluids, both for early diagnosis of metastatic disease, and for the diagnosis of primary tumor when serous effusion is the first manifestation of the neoplasia.

CONTEXT AND OBJECTIVE: Spontaneous bacterial peritonitis (SBP) is a complication of ascites, especially in cirrhosis. Ascitic fluid with 250 or more neutrophils/mm 3 is an acceptable criterion for diagnosis, even when bacterial fluid cultures are negative. The aims here were to estimate SBP frequency among emergency room patients based on cellular criteria and evaluate the biochemical profile of these fluids. DESIGN AND SETTING: Retrospective study at a public tertiary hospital. METHODS: Laboratory records of patients with ascites attended in emergency rooms between November 2001 and November 2006, from whom ascitic fluid samples were sent to the laboratory due to suspected SBP, were evaluated. The 691 samples included were divided into group A (presumed SBP: ≥ 250 neutrophils/mm 3 ; n = 219; 31.7%) and group B (no presumed SBP: < 250 neutrophils/mm 3; n = 472; 68.3%). Patients' sex and age; ascitic fluid characteristics (numbers of neutrophils, leukocytes and nucleated cells); bacteriological characteristics; and protein, lactate dehydrogenase, adenosine deaminase and glucose concentrations were evaluated. RESULTS: Among group A cultured samples, 63 (33.8%) had positive bacterial cultures with growth of pathogens commonly associated with SBP. In total, the group A samples showed higher lactate dehydrogenase levels than seen in the group B samples. The latter presented predominance of lymphocytes and macrophages. CONCLUSION: Among the ascitic fluid samples with clinically suspected SBP, 31.7% fulfilled the cellular diagnostic criteria. Positive bacterial isolation was found in 33.8% of the cultured samples from the presumed SBP group. reSUMOCONTEXTO E OBJETIVO: Peritonite bacteriana espontânea (PBE) é uma complicação da ascite, especialmente na cirrose. Líquido ascítico com 250 ou mais neutrófilos/mm 3 é um critério aceitável para o diagnós-tico, mesmo com cultura bacteriana negativa. Os objetivos foram estimar a frequência de PBE em pacientes atendidos na sala de emergência, baseando-se no critério celular e avaliar o perfil bioquímico desses líquidos peritoneais. TIPO DE ESTUDO E LOCAL: Estudo retrospectivo em hospital público terciário. MÉTODOS: Foram avaliados registros laboratoriais de pacientes com ascite atendidos no setor de emergên-cia entre novembro de 2001 e novembro de 2006, cujas amostras de líquido ascítico foram encaminhadas ao laboratório por suspeita de PBE. As 691 amostras incluídas foram divididas em grupo A (PBE presumida: ≥ 250 neutrófilos/mm 3 ; n = 219; 31.7%) e grupo B (Ausência de PBE presumida: < 250 neutrófilos/mm 3; n = 472; 68.3%). Também foram avaliados sexo e idade dos pacientes além de características dos líquidos ascíticos: número de neutrófilos, leucócitos e células nucleadas; bacteriologia; e concentrações de proteínas, desidrogenase láctica, adenosina deaminase e glicose. RESULTADOS: Das amostras cultivadas do grupo A, 63 (33,8%) tiveram cultura bacteriana positiva com crescimento de patógenos comumente associados à PBE. O total de amostras do grupo A exibiu maiores ní...

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