FNAC and biopsy are both methods of obtaining material from a suspicious lesion for pathological examination, but they differ in what they collect, what they can tell us, and when each is the appropriate investigation. FNAC uses a fine needle to aspirate cells from a lump. The material collected is cells: individual cells or small clusters, without the surrounding tissue architecture. The pathologist examining an FNAC looks at the cellular characteristics, the types of cells present, and whether they appear benign, reactive, or malignant. FNAC is quick, minimally invasive, and provides a rapid preliminary answer. It is the right first step for a thyroid nodule, a neck lymph node, a breast lump, or a salivary gland swelling, where it can usefully distinguish benign from suspicious from malignant without the discomfort or procedure time of a formal biopsy. A biopsy, whether a core needle biopsy performed with a larger needle that removes a cylindrical core of tissue, or a surgical biopsy that removes a portion or all of the lesion, collects tissue rather than just cells. The pathologist examining a biopsy sees not only the individual cells but the tissue architecture: how the cells are arranged relative to each other, whether there is invasion of surrounding structures, what the supporting stroma looks like, and whether the tumour is replacing or distorting the normal tissue. This architectural information is essential for definitive cancer diagnosis and grading, for distinguishing in-situ from invasive cancer, and for many specific tumour types where the diagnosis depends on architectural patterns rather than cytological features alone.
The general principle I follow at PESIMSR, Kuppam, is that FNAC is the appropriate first step for most palpable lumps because it provides rapid, minimally invasive preliminary information. If the FNAC is benign and correlates with the clinical and imaging assessment, watchful waiting or excision can be planned. If the FNAC is suspicious or malignant, a core biopsy or surgical biopsy is the next step to provide the tissue architecture and IHC information needed for complete diagnosis and treatment planning.
Written by Dr. Anikode Subramanian Ramaswamy, MBBS, MD (Pathology), Professor and Head, Department of Pathology, PESIMSR, Kuppam, Andhra Pradesh 517425. ISO 15189 Assessor. 75 peer-reviewed publications. Phone: +91 9493726494.
