Phosphohistone H3 (PHH3) Immunohistochemical Staining Outperforms Conventional H&E Mitotic Count in Classifying Pulmonary Carcinoids

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Introduction: Pulmonary carcinoids (PC) are well-differentiated NETs and are classified as typical carcinoid (TC) and atypical carcinoid (AC). Despite the fact that TC and AC exhibit significant differences in patient survival, their classification depends on relatively subtle differences in mitotic count (MC). Although careful counting of mitotic figures (MF) is essential, it is a very subjective task, time-consuming and lacks of sensitivity and interobserver reproducibility, due to selection bias of the hot spots, heterogeneous distribution of MF, difficulty in distinguishing MF from similar chromatin changes (i.e. in apoptotic cells or due to crush, karyorrhectic debris, pyknosis or apoptosis).

Aim(s): Identification of MF could be facilitated by the use of mitosis-specific immumostaining such as PHH3.

Materials and methods: 47 PC cases were selected and immunostained for PHH3. MF on both H&E- and PHH3-stained slides were counted in hot spots and per 2 mm2. In tumours that are near the cutoff of 2 per 2 mm2, at least 3 sets of 2 mm2 were counted and the mean used for determining the MC.

Conference: 15th Annual ENETSConcerence (2018)

Presenting Author: Luong T

Authors: Luong T, McCaughran W, Caplin M, Toumpanakis C, Thirlwell C,

Keywords: Phosphohistone H3, Pulmonary Carcinoids, Typical Carcinoid, Atypical Carcinoid, Mitotic Count, H&E,