Morphological differentiation of hyperchromatic crowded groups (HCG) in cervical cytology. Possible clinical significance

Abstract

HCG groups (hyperchromatic crowded groups) are hyperchromatic cellular aggregates observed during routine screening for cancer and premalignant intraepithelial lesions in both negative and abnormal cervical cytology samples. This study aimed to characterise the cytomorphological features of HCG groups in cervical cytology samples, in order to classify them as benign/reactive, atypical, or potentially neoplastic, and to explore their clinical significance in this setting. Conventional cervical cytology samples that were satisfactory for analysis and exhibited HCG groups were selected. Of 2810 cytological cases, 70 (2.49%) met the inclusion criteria. HCG groups were identified in 41% of negative cytology samples and in 59% of abnormal samples. Atypical HCG groups (ASC-H) were the most common (24.28%), followed by potentially neoplastic/HSIL (17.14%). The morphology of HCG groups is variable, necessitating carefully recognition, differentiation, and interpretation, particularly in abnormal cases requiring detailed and systematic evaluation. In cases with a clear HSIL context, the presence of HCG groups composed of squamous metaplastic cells or cells with a glandular appearance may raise suspicion of intracanal HSIL, which should be confirmed by histopathological examination. Comprehensive assessment of both cellular and background features in cytological smears helps clarify the origin of HCG groups, ensuring accurate morphological characterisation and appropriate cytological classification and clinical interpretation. Clinical and epidemiological information is essential for the accurate classification of HCG groups.