Hyperchromatic crowded cell groups in gynaecological liquid-based cytology samples

Cervical cytology screening is a complex and demanding procedure. Correct diagnosis depends on accurate interpretation of cells, including dense clusters known as hyperchromatic crowded cell groups (HCCG). These groups are frequently encountered in liquid-based cytology (LBC) samples and can be difficult to identify as a specific cell type. Although usually benign and thus often overlooked, they may occasionally represent severely abnormal cells. Thus, their correct interpretation is vital for accurate reporting. Such groups are responsible for false-positive and false-negative reporting and have been implicated in cases of missed dyskaryosis and cervical cancer. Normal and abnormal cells of both squamous and glandular origin, together with non-epithelial elements, may present as HCCG and this review uses the authors' experience with SurePath to describe the morphological criteria used to evaluate them when screening. Despite the introduction of semi-automated screening systems for LBC, there is currently no complete replacement for human interpretation of cell morphology in cytology screening.