Do we truly see what we think we see? The role of cognitive bias in pathological interpretation.

In the histomorphological grading of prostate carcinoma, pathologists have regularly assigned comparable scores for the architectural Gleason and the now-obsolete nuclear World Health Organization (WHO) grading systems. Although both systems demonstrate good correspondence between grade and survival, they are based on fundamentally different biological criteria. We tested the hypothesis that this apparent concurrence between the two grading systems originates from an interpretation bias in the minds of diagnostic pathologists, rather than reflecting a biological reality. Three pathologists graded 178 prostatectomy specimens, assigning Gleason and WHO scores on glass slides and on digital images of nuclei isolated out of their architectural context. The results were analysed with respect to interdependencies among the grading systems, to tumour recurrence (PSA relapse > 0.1 ng/ml at 48 months) and robust nuclear morphometry, as assessed by computer-assisted image analysis. WHO and Gleason grades were strongly correlated (r = 0.82) and demonstrated identical prognostic power. However, WHO grades correlated poorly with nuclear morphology (r = 0.19). Grading of nuclei isolated out of their architectural context significantly improved accuracy for nuclear morphology (r = 0.55), but the prognostic power was virtually lost. In conclusion, the architectural organization of a tumour, which the pathologist cannot avoid noticing during initial slide viewing at low magnification, unwittingly influences the subsequent nuclear grade assignment. In our study, the prognostic power of the WHO grading system was dependent on visual assessment of tumour growth pattern. We demonstrate for the first time the influence a cognitive bias can have in the generation of an error in diagnostic pathology and highlight a considerable problem in histopathological tumour grading.

Follicular variant of papillary thyroid cancer in Alström syndrome.

Alström syndrome (AS) is an autosomal recessive disorder, characterized by cone-rod dystrophy, sensorineural hearing loss, obesity, hyperinsulinemia with insulin resistance, type 2 diabetes mellitus and progressive pulmonary, hepatic and renal dysfunction. AS is caused by mutations in the ALMS1 gene, located on the short arm of chromosome 2. We report a 35-year-old woman with known history of AS, who developed a follicular variant of papillary thyroid carcinoma. To our knowledge this is the first association of AS with thyroid malignancy, among the approximately 450 cases reported since the first description of the syndrome. We conclude that papillary thyroid carcinoma should be considered in the differential diagnosis of thyroid nodules in patients with AS.

[Hamartoma of the duodenum]. / Das Hamartom des Duodenums. Eine seltene Indikation zur partiellen Duodenopankreatektomie.

HISTORY AND ADMISSION FINDINGS: A 61-year-old man had been suffering from repeated episodes of postprandial vomiting and a feeling of fullness as well as a weight loss of 8 kg for two months. Three years prior to this, a laparoscopic cholecystectomy had been carried out at a different institution after a pancreatitis on the assumption of a biliary genesis. There were no sings of jaundice or gastro-intestinal bleeding. The physical examination was -- apart from epigastric pain -- unremarkable. INVESTIGATIONS: The routine laboratory parameters and tumor markers were within normal range. Endoscopy revealed a thickened duodenal wall with a stenosis at the level of the papilla, and a tumorous mass in the duodenal bulb. The biopsy specimens gave no evidence of malignancy. The barium upper GI series revealed an excentric stenosis of the duodenal pars II. Computerized tomography showed no evidence for tumor growth extending beyond the wall or a pathologic enlargement of the adjacent lymph nodes. THERAPY AND COURSE: A pylorus-preserving partial duodenopancreatectomy was performed and the postoperative course was without any complications. The histological examination of the resectate showed -- besides a chronically fibrosing pancreatitis -- a hamartoma of the duodenal wall. CONCLUSION: Besides the endoscopic removal of a hamartoma of the duodenum a surgical transduodenal resection represents the most frequently applied procedure. The partial duodenopancreatectomy is a rather rare therapeutic option. It was chosen in our patient on account of the atypical presentation of the tumor, unclear histology and an adequate operative risk.

Anomalous diffusion of water in biological tissues.

This article deals with the characterization of biological tissues and their pathological alterations. For this purpose, diffusion is measured by NMR in the fringe field of a large superconductor with a field gradient of 50 T/m, which is rather homogenous and stable. It is due to the unprecedented properties of the gradient that we are able not only to determine the usual diffusion coefficient, but also to observe the pronounced Non-Debye feature of the relaxation function due to cellular structure. The dynamics of the probability density follow a stretched exponential or Kohlrausch-Williams-Watts function. In the long time limit the Fourier transform of the probability density follows a long-tail Lévy function, whose asymptotic is related to the fractal dimension of the underlying cellular structure. Some of the properties of Lévy walk statistics are discussed and its potential importance in understanding certain biophysical phenomena like diffusion processes in biological tissues are pointed out. We present and discuss for the first time NMR data giving evidence for Lévy processes that capture the essential features of the observed power law (scaling) dynamics of water diffusion in fresh tissue specimens: carcinomas, fibrous mastopathies, adipose and liver tissues.