Warum muss ein Schilddrüsentumor als Karzinom klassifiziert werden, wenn er sich biologisch nicht wie Krebs verhält?

[Diagnostic principles of thyroid tumors in pathology : Relevant changes due to the current WHO classification]

The current edition of the WHO classification of thyroid tumors (2017) contains a number of very relevant changes with considerable consequences for the diagnostic assessment of thyroid specimens. This applies to both the histomorphological examination of surgical specimens and the preoperative fine needle biopsy (FNB). In addition, molecular pathological examinations are becoming increasingly important in the diagnosis of thyroid tumors. Changes affect practically all areas of thyroid tumor diagnostics. Some of these changes have far-reaching consequences that justify a comprehensive commentary and query of the knowledge acquired in the form of this CME article.

[Pathology and molecular profile of differentiated thyroid carcinoma]

The clinical term of differentiated thyroid carcinoma (DTC) includes follicular (FTC) and papillary thyroid carcinomas (PTC). In diagnostic thyroid pathology, however, the term differentiated carcinoma (NOS) is used only very rarely for tumors with morphological features of both FTC and PTC. The current World Health Organization (WHO) classification of thyroid tumors introduced the entity of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). As a result, the diagnostic criteria for PTC had to be adjusted (compulsory histological demonstration of invasion and/or papillae), which also significantly limited the diagnostic potential of a fine needle biopsy (FNB) of the thyroid. The FTC is now divided into three distinct subgroups. Moreover, the WHO classification also established the diagnostic criteria of poorly differentiated thyroid carcinoma (PDTC), which has to be distinguished from both differentiated carcinomas and benign adenomas. This article also summarizes the current diagnostic status of molecular pathological analyses of thyroid tumors.

[The influence of the pathologist on the mental well-being of the patient]

The label cancer in itself leads to complex psychological reactions in patients that are closely related to previous experiences and self-image. A cancer diagnosis can lead to increased distress and subsequent mental comorbidity such as depression or anxiety disorders. The responsibility of the pathologist, as the person who first uses the label cancer, is high. The pathologist must be conscious and focus not only on the accuracy of the anatomical pathology, but also on the potential influences the wording may have on the mental health of the patient. The word "carcinoma" should only be used in the case of tumors with the respective biological behavior. The example of non-invasive follicular thyroid neoplasm with papillary-like nuclear features shows that changing a label can lead to an improvement in distress and quality of life.