False negative rate. A misnomer, misunderstood and misused.

By rigorous statistical standards, the expression false negative rate is a misnomer because the concept of "rate" is associated with the rapidity of change of phenomena per unit of time or other variable (e.g., temperature). Uncertainty about the term false negative rate resulted in the introduction of similar but equally dubious expressions, including false negative fraction and miss rate. The statistically correct term in the practice of cytopathology is false negative proportion because we have here a fraction in which the numerator (number of false negative cases) is a part of the denominator (number of true positive cases plus number of false negative cases). This is the classic definition of the term proportion.

Sample size calculations for rescreening cytologic smears.

OBJECTIVE: To describe a method of calculating sample size if rescreening of cytologic material becomes necessary for legal or other reasons. The number of specimens to be reexamined must be large enough to provide adequate confidence in the results and small enough to minimize the cost of investigation. CONCLUSION: Except under very unusual conditions, the sample size is larger than generally thought.

False-positive and false-negative proficiency test results in cytology.

Proficiency tests in cytology classify a certain proportion of cytologists inaccurately. Some competent cytologists fail during the testing procedure ("false-negative proficiency test" or "type I error") while some individuals who should fail do pass the test ("false-positive proficiency test" or "type II error"). In other words, success or failure during proficiency testing may be the consequence of statistical chance. Calculations based on the binomial distribution are presented to show the seriousness of this problem. The analysis demonstrated that increasing the number of slides in the test sets does not necessarily improve the accuracy of the test. For instance, on the 90% ("borderline competent") level, raising the number of slides in one test set from 10 to 20 reduced the accuracy of the test by 6%.

Intracytoplasmic eosinophilic inclusion bodies in breast cyst fluids are giant lysosomes.

Electron microscopic (EM) studies were performed on a benign breast cyst fluid to determine the nature of intracytoplasmic eosinophilic inclusion bodies (EIBs). EIBs were usually found in macrophages and had the ultrastructural appearance of giant lysosomes. EIBs contained cellular material and granular debris; when viewed by EM, the contents were somewhat variable, depending on the nature of phagocytosed material and the extent of enzymatic breakdown. Usually the phagocytosed material had a rather homogeneous, finely granular texture. Occasionally cell remnants, including cytoplasmic organelles, were preserved inside the EIBs. Since the "host" macrophages were in various states of degeneration, the formation of EIBs appears to be related to a severe disturbance in the macrophage cellular function. This study showed that EIBs in cells from breast cyst fluids are not viral particles.

Intracytoplasmic eosinophilic inclusion bodies in benign breast cyst fluids.

Intracytoplasmic eosinophilic inclusion bodies (EIBs) observed in cytologic preparations of benign breast cyst fluid aspirates were morphologically similar to the well-known EIBs in urine specimens. EIBs have not been previously described in breast cyst fluids. A chi-square test proved a statistically significant correlation between the presence of intracellular EIBs and cellular degeneration. The possible significance of this finding with regard to the origin of EIBs is discussed.

The pathogenesis of bladder cancer.

Carcinoma of the urinary bladder appears to arise, in at least some cases, from carcinoma in situ developing in a field of atypical epithelial proliferation. There is both a spatial and temporal relationship between invasive and in situ bladder cancer, although the exact relationship between the noninvasive flat and papillary types of tumors is not known. Prenoeplastic bladder lesions are defined as irreversible, although not necessarily progressive, and an experimental animal model of the disease has been developed. The appearance of pleomorphic microvilli on the luminal surface of epithelial cells of the urinary bladders of Fischer rats is correlated with the irreversibility of hyperplastic epithelial lesions induced by feeding N-[4-(5-nitro-2-furyl)-2-thiazolyl] formamide (FANFT) to the test animals. This alteration can be visualized by scanning electron microscopy of cytologic and histologic preparations.