Pitfalls in Thyroid Pathology and the Medicolegal Aspects of Error

This article is a brief review of diagnostic error in thyroid cytopathology and histopathology with a discussion of more general medicolegal aspects of error in histopathology and cytopathology relevant to thyroid pathology. Pre-operative ultrasound guided thyroid FNA cytology is the standard pre-operative investigation for thyroid nodules. FNA is effective in triaging thyroid nodules. The cytological features of papillary thyroid carcinoma are readily identified in FNA specimens. Needle core biopsy may also be useful in some circumstances if fine-needle aspiration is unhelpful. Errors tend to occur in thyroid pathology due to a number of relatively well-known diagnostic pitfalls. Strategies to reduce diagnostic errors include careful attention to known pitfalls and the clinical history. Previous fine-needle aspiration or core biopsy may produce artefacts that can mimic capsular invasion. Other helpful strategies include double or consensus reporting of suspected problematic lesions, e.g. follicular tumour of uncertain malignant potential vs. minimally invasive follicular thyroid carcinoma, sampling of the whole lesion capsule if capsular or vascular invasion is suspected and judicious use of additional levels and immunostains if vascular or lymphatic invasion is suspected. The importance of multidisciplinary case review is also highlighted.