Patient selection: complete resection of an encapsulated Hurthle cell carcinoma
Criteria for an encapsulated Hurthle cell carcinoma:
(1) well-defined and encapsulated
(2) no macroscopic evidence of vascular or capsular invasion
(3) consists of 76-100% (> 75%) follicular oncocytic cells
The primary risk factor for recurrence was >= 4 foci of vascular invasion (termed extensive vascular invasion).
Histologic features associated with >= 4 foci of vascular invasion:
(1) solid /trabecular growth pattern (versus follicular pattern)
(2) mitotic rate >= 1 per 10 high powered fields (hpf, 400x total magnification)
The authors recommended that any encapsulate Hurthle cell tumor with solid/trabecular growth and/or mitotic activity should be diligently examined for foci of vascular invasion.
In univariate analysis, a tumor diameter > 4 cm was associated with decreased recurrence-free survival.
