Encapsulated Papillary Thyroid Tumor with Delicate Nuclear Changes and a KRAS Mutation as a Possible Novel Subtype of Borderline Tumor
- Author:
Kenji OHBA
1
;
Norisato MITSUTAKE
;
Michiko MATSUSE
;
Tatiana ROGOUNOVITCH
;
Nobuhiko NISHINO
;
Yutaka OKI
;
Yoshie GOTO
;
Kennichi KAKUDO
Author Information
- Publication Type:Case Report
- Keywords: Borderline/precursor tumor; Observer variation; RAS-like tumor
- MeSH: Adenoma; Adult; Diagnosis; Humans; Hyperplasia; Observer Variation; Point Mutation; Referral and Consultation; Thyroid Gland; Thyroid Neoplasms
- From:Journal of Pathology and Translational Medicine 2019;53(2):136-141
- CountryRepublic of Korea
- Language:English
- Abstract: Although papillary thyroid carcinoma (PTC)–type nuclear changes are the most reliable morphological feature in the diagnosis of PTC, the nuclear assessment used to identify these changes is highly subjective. Here, we report a noninvasive encapsulated thyroid tumor with a papillary growth pattern measuring 23 mm at its largest diameter with a nuclear score of 2 in a 26-year-old man. After undergoing left lobectomy, the patient was diagnosed with an encapsulated PTC. However, a second opinion consultation suggested an alternative diagnosis of follicular adenoma with papillary hyperplasia. When providing a third opinion, we identified a low MIB-1 labeling index and a heterozygous point mutation in the KRAS gene but not the BRAF gene. We speculated that this case is an example of a novel borderline tumor with a papillary structure. Introduction of the new terminology “noninvasive encapsulated papillary RAS-like thyroid tumor (NEPRAS)” without the word “cancer” might relieve the psychological burden of patients in a way similar to the phrase “noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).”
