Insulin-like growth factor-II mRNA-binding protein 3 immunocytochemical expression in direct endometrial brushings: Possible diagnostic help in endometrial cytology.

Introduction: This study evaluated the immunocytochemical (ICC) expression of IMP3 in direct endometrial brushings processed as liquid-based cytology (LBC) samples of endometrioid adenocarcinoma (EAC), serous carcinoma (ESC) and surface papillary syncytial change (SPSC) with endometrial glandular and stromal breakdown (EGBD) to exploit its possible differential diagnostic aid.

Methods: In total, 333 samples of LBC samples were obtained from selected outpatients in parallel with Pipelle endometrial sampling. They consisted of 97 EAC (83 grade 1: EAC-1, 14 EAC-3), 35 ESC and 201 benign endometrial samples (51 proliferative, 42 secretory, 38 atrophic, 70 SPSC with EGBD). ICC expression of insulin-like growth factor-II mRNA-binding protein 3 (IMP3) was manually performed on Papanicolaou-stained LBC samples.

Results: The ESC samples showed positive staining cells in 100%, EAC-3 in 28.5%, and EAC-1 in 2.4% cases. All the benign endometrium samples were negative. Only ESC cases showed strong immunoreactivity (≥3+) in more than 50% of tumour cells with an average frequency of 80%.

Conclusions: IMP3 is a helpful immunomarker to distinguish ESC from EAC and SPSC in endometrial cytology.