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NeuroTest Question #16 Next question Previous question

Answer: B (Malignant hyperthermia) Level of difficulty: 4 NeuroTest NeuroLearn NeuroHelp

Discussion:

Lesion under discussion: This is a muscle biopsy specimen and is blue. All fibers being show here appear to be type I fibers. A central pale area of staining is present in practically all fibers. These findings are most suggestive of either central core disease or target fibers. The three zone architecture that is typical for target fibers is not present. The most appropriate diagnosis should be central core disease which has well documented association with malignant hyperthermia. Malignant hypertension and malignant tumor of the central nervous system are not associated with central core disease and. in fact, hardly with any primary myopathies.
Central core disease: This is the first congenital myopathy being recognized. Central core disease is most often seen in children but can also become symptomatic in adults. Some of them remain asymptomatic. Most likely, it is autosomal dominant. Mutations in the gene for the ryanodine receptor on chromosome 19q have been found in some patients with central core disease. Patients are susceptible to develop malignant hyperthermia. The pathologic hallmark is a centrally located core in a muscle fiber that is composed of disorganized myofibrils. Histochemically, the core does not contain oxidative enzymes and appears as pale areas on NADH-TR, SDH and cytochrome C oxidase preparations. [Click here to see longitudinal secion of central core] [Click here to see a case]