Abstract. Relatively little is known about the occurrence of neurocysticercosis in northeastern Brazil. There have been no published reports from the state of Ceará, but a review of the records at the Hospital São José in Fortaleza, Brazil identified 119 patients with neurocysticercosis diagnosed between January 1988 and April 1994. Patients came from 43 municipalities in Ceará. Their ages ranged from five to 74 years; the greatest number of cases were in persons 10-40 years of age; 63% were males. Seizures were the presenting complaint in 64% of the patients and headache in 22%. Two patients, each with several hundred intracranial lesions, presented with mental status changes; one was initially given the clinical diagnosis of viral meningoencephalitis. Computed tomography scans showed that 44% of the patients had five or more lesions. Cysts were found throughout the brain. The parietal lobe was the most frequent site of involvement; 85% of patients had one or more lesions there. The brain stem was involved in 8%. There was no consistent association between the severity of the clinical abnormalities and the radiologic findings. Computed tomography of the thighs was done in 10 persons; cysts were identified in nine.Cysticercosis is an important health problem throughout Latin America from Mexico to Peru, 1-4 but relatively little is known about its impact in northeastern Brazil. The disease is found in developing areas where pigs are raised and sanitation is poor. 5 Transmission occurs when humans ingest ova in food or water that has been contaminated with feces from humans who harbor adult Taenia solium. Ova excyst in the intestine releasing larvae that invade and form tissue cysts (cysticeri) in brain, muscle, eye, or other tissues.Involvement of the central nervous system results in neurocysticercosis, an important cause of seizures and other neurologic abnormalities among residents of endemic areas. Neurocysticercosis is encountered in the United States among immigrants from endemic areas. 6 Cases of cysticercosis have also been reported among residents of North America who have never visited endemic areas, but who have been exposed to immigrants infected with adult T. solium. [6][7][8] As this series illustrates, neurocysticercosis is an important cause of morbidity in northeastern Brazil. METHODSThe records of the Hospital São José, located in Fortaleza in the state of Ceará were reviewed for the period January 1988 through April 1994 to identify cases of neurocysticercosis. Patients were included in the study if they had neurologic symptoms or signs and a head computed tomography (CT) scan that documented single or multiple cystic lesions in the brain, with or without contrast enhancement; if there were enhancing nodular lesions; if there were small calcified lesions; or if there was a combination of the these findings (Figure 1). In 13 (11%) cases the diagnosis was confirmed by biopsy. Serological studies were not routinely performed. The age and sex of the patients, their home municipalities, their prese...

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Variation of rearrangement of regulatory genes is responsible for cellular malignant change. These types of chromosomal variations also produce heterochrony or paedomorphic evolution at the organismal level. Analogously, neoplasia represents a cellular 'macroevolutionary' event, and a tumour can be said to be an evolved population of cells. To understand this cellular evolution to malignancy, it may be necessary to go beyond a 'clonal selection' (adaptationist) explanation of neoplastic alteration. In the pericellular environment 'natural selection' consists of the organizational restraints of surrounding cells as well as the host's immunological surveillance and non-specific monocyte-macrophage systems. Indirect evidence suggests that success for the neoplasm depends not upon 'clonal selection', but solely upon a genetic methodology-the function of which is to elude selection. The author has coined the term 'cellular heterochrony' to illustrate analogic similarities in the molecular modes of speciation between anaplastic cancer cells and the heterochronic evolution of organisms. By reverting to juvenile (embryonic) repertoire of cellular behaviour a tumour secures its own tenure or niche by usurping the host's armamentarium of selection forces, employing many of the same or similar methods by which implanting and invading tissues of the mammalian embryo forestall maternal detection and rejection. A number of ways by which the tumour blocks, subverts or evades selection are discussed.

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