Cytomorphological Features of Hyperchromatic Crowded Groups in Liquid-Based Cervicovaginal Cytology: A Single Institutional Experience.

Hyperchromatic crowed groups (HCGs) are defined as three-dimensional aggregates of crowded cells with hyperchromatic nuclei, and are frequently encountered in cervicovaginal liquid-based cytology (LBC). Here, we aimed to examine the prevalence of HCGs in cervicovaginal LBC and the cytomorphological characteristics of various epithelial cell clusters presenting as HCGs.We first examined the prevalence of HCGs in a "routine cohort" of LBC cytology (n=331), consisting of all cervicovaginal LBCs accessioned over three days from outpatient clinics (n=179) and the screening population (n=152). Then we examined a second "high-grade epithelial cell abnormalities (H-ECA) cohort" (n=69) of LBCs diagnosed as high-grade squamous intraepithelial lesion (HSIL), squamous cell carcinoma (SCC) or adenocarcinoma during one year.HCGs was observed in 34.4% of the routine cohort and were significantly more frequent in the ECA category compared to the non-neoplastic category (p=0.003). The majority of HCGs represented atrophy (70%). Of the 69 histologically confirmed H-ECA cases, all contained HCGs. The majority of cases were HSIL (62%), followed by SCC (16%). Individually scattered neoplastic cells outside the HCGs were significantly more frequent in SCCs compared to glandular neoplasia (p=0.002). Despite the obscuring thick nature of the HCGs, examining the edges and the different focal planes of the HCGs and the background were helpful in defining the nature of the HCGs.HCGs were frequently observed in cervicovaginal LBC and were mostly non-neoplastic; however, neoplastic HCGs were mostly high-grade lesions. Being aware of the cytomorphological features of different HCGs is important in order to avoid potential false-negative cytology interpretation.