Histotype

Histotype is a term used in biology and medicine to denote a histological type, i.e., the classification of a tissue or neoplasm based on its microscopic structure and cellular morphology. The designation reflects the tissue of origin and degree of differentiation as observed in histological sections. In pathology, histotypes are used to categorize tumors into subtypes with distinct clinical behavior, prognosis, and potential therapeutic options.

In oncology, histotype classification helps guide treatment decisions and prognostication. Examples include breast cancer, which can be organized into ductal and lobular histotypes; ovarian cancer, classified as serous, mucinous, endometrioid, or clear cell histotypes; and lung cancer, described by histotype as adenocarcinoma, squamous cell carcinoma, or small cell carcinoma. These histological categories are increasingly integrated with molecular profiling to inform targeted therapies and personalized care.

Determining histotype relies on tissue biopsy and histopathological examination, often supported by immunohistochemical staining and, when needed, genetic or molecular testing. While histotype emphasizes morphology, tumors can exhibit intratumoral heterogeneity, and mixed histology may be present. Misclassification can arise from sampling bias or interpretive variation. In research and clinical reporting, histotype provides a fundamental framework for studying tumor origin, differentiation pathways, and responses to treatment.