We reviewed clinical data and quantitative muscle biopsy data from infants with hypotonia and developmental delay who had relatively small type 1 muscle fibers (fiber size disproportion; FSD). Study material consisted of 49 thigh muscle specimens from 37 patients, 1 week to 11.5 years old, who had FSD diagnosed between 1971 and 1985. Beyond 2 months of age, FSD was greater than 12% in at least one biopsy from all but 2 patients. In sequential specimens obtained from 11 patients, we observed that FSD may resolve, persist unchanged, or intensify with age. In 6 patients, hypotonia regressed, and development tended to normalize during 1-4 years of observation; FSD resolved in 4 cases, but numerical predominance of type 1 fibers persisted in 3 of them. In a small group designated congenital myopathy with FSD only, the disproportion in fiber diameter persisted unchanged or intensified with time and was more severe after the age of 6 months than in the other subgroups. We classified FSD as definitely or probably myopathic (15 cases), definitely or probably neuropathic (17 cases), and benign maturation delay (5 cases). Six of 17 neuropathic cases had a history of perinatal asphyxia. In most cases, type 1 fibers were absolutely small and type 2 fibers were hypertrophied, independent of classification. FSD is a manifestation of muscle maturation delay of variable etiology. The prevalence of nervous system disorders in our series suggests that neuronal dysfunction plays an important role in pathogenesis. We were unable to define morphometric criteria that consistently distinguished congenital myopathy with FSD from definable neuropathic FSD or from benign maturation delay.
A fatal case of diphtheria occurred in a nonimmunized child. The child died because of the late diagnosis of the disease, which is now extremely rare.
This review discusses the neuropathological issues pertaining to temporal lobectomies and neocortical resections for medically refractory seizures of childhood. Most cases in our pediatric series are ''lesional'' and have CT/MRI abnormalities that contribute to a higher incidence of ''dual pathology'' lesions rather than pure mesial temporal sclerosis. Almost up to two thirds of our cases are represented by neuronal migration disorders and low grade gliomas. We have also encountered lesions that have both neoplastic and malformative foci, some of which behave more like tumors, while others defy precise classification as tumor or malformation. Our preliminary data indicate a role for cytomegalovirus in some cases of Rasmussen's encephalitis.
We report the necropsy findings for three infants with the unusual combination of proximal renal tubular dysgenesis and severe congenital liver disease with excessive iron in several organs resembling neonatal hemochromatosis. Two of the infants were caucasian siblings and one was an Australian aborigine. One died in utero at 35 weeks of gestation and two died at 7 days. The liveborn infants presented with anuria and liver failure. The livers all showed marked loss of hepatocytes and replacement by pseudotubules in the collapsed lobules. The liveborn infants also showed giant cell transformation ofhepatocytes, small regenerative nodules, cholestasis, and normal bile ducts. Absence of proximal renal convolutions was confirmed by epithelial membrane antigen positivity in nearly all tubules. In each family there was another sibling with congenital liver disease, fatal in one case, but no renal tubular dysgenesis. No infection or metabolic disease was uncovered in any of our patients, and the cause of the hepatocyte destruction was not determined. The combination in three infants of two rare congenital diseases could be genetic or acquired in utero from the same etiological agent. Alternatively, the absence of proximal convolutions could be secondary to hypoperfusion, perhaps because of shock due to extensive necrosis of hepatocytes.
