Messages from Kennichi Kakudo, MD, PhD to a person to be an expert of the cytopathology

As pointed out by many authors, observer disagreements between benign and malignant often occur in diagnoses of encapsulated thyroid tumor with incomplete papillary carcinoma type nuclear features (PTC-N) (Kakudo K et al. Encapsulated papillary thyroid carcinoma, follicular variant: a misnomer. Pathol Int. 62(3):155-160, 2012. Review.). These tumors are indolent and usually do not create any harm to the patients, but the malignant diagnosis may create overtreatments to the patients when the clinical doctors did not aware the indolent nature of the tumor. Particularly in US, the patients with PTC, either common type or follicular variant, with or without capsulation, with or without invasive growth and with or without metastasis, are treated with total thyroidectomy followed by radio-active iodine (RAI) treatment. (Please refer Letter from a USA patient in my HP) I believe many of the patients with encapsulated non-invasive follicular variant PTC in Western countries were treated with completion of total thyroidectomy followed by RAI treatment. To stop this overtreatment to the indolent tumors, many authors published their opinions how to prevent overtreatment (Luster M et al: Differentiated thyroid cancer-personalized therapies to prevent overtreatment. Nat Rev Endocrinol 10:563-574, 2014 and Esserman LJ et al: Addressing overdiagnosis and overtreatment in cancer: a prescription for change. Lancet Oncol, 15:e234-242, 2014)

To solve this diagnostic issue, A Working Group for Re-examination of the Encapsulated Follicular Variant of Papillary Thyroid Cancer was organized in 2014. The mission of this working group is to establish a histopathologic criteria of encapsulated non-invasive follicular variant PTC and find a new name more suitable for indolent nature of this tumor. Patients with this tumor are also invited to the meeting at USCAP symposium. We are going to see a happy end of this diagnostic issue soon, and I hope this solution will help prevent overtreatment to the patient with encapsulated thyroid tumor with PTC-N in the future.