Does having a biopsy guarantee a definitive diagnosis of whether it is benign or malignant?
Oct 30, 2025
Source: Cainiu Health
Dr. Wang Lei
Introduction
In general, a biopsy does not always 100% confirm whether a tumor is benign or malignant. In most cases, biopsy is an accurate diagnostic method, but there are rare instances where the diagnosis remains unclear due to factors such as sampling errors or pathological types. If the biopsy results are inconclusive, doctors usually recommend repeating the biopsy or performing surgical removal of the lesion followed by a complete pathological examination.
In general, a biopsy does not always 100% confirm whether a tumor is benign or malignant. In most cases, biopsy is an accurate diagnostic method, but there are still rare instances where the diagnosis remains inconclusive due to factors such as sampling issues or pathological characteristics. The details are as follows:
The core of biopsy diagnosis lies in obtaining a small tissue sample from the affected area and examining it pathologically—pathological examination being one of the "gold standards" for determining benignity or malignancy. In most cases, if the biopsy sample is sufficient and accurately taken from the lesion site, allowing clear observation of cellular morphological features, a definitive diagnosis of benign or malignant can be made. For example, the diagnostic accuracy of biopsies for common tumors such as breast cancer and lung cancer is relatively high.
However, certain situations may affect the reliability of biopsy results. First, sampling issues: if the lesion is too small, located in a hidden area, or if the needle fails to reach the core region of the lesion during biopsy—resulting in only normal or necrotic tissue being collected—a definitive conclusion may not be possible. Second, special pathological types: some tumor cells have atypical morphology, falling into a gray zone between benign and malignant, making them difficult to distinguish by routine pathological examination alone; additional tests such as immunohistochemistry or genetic testing may be required for clarification. Third, technical limitations: different biopsy techniques yield varying amounts of tissue, which can impact diagnostic accuracy. Fine-needle aspiration, for instance, provides limited tissue samples, which may sometimes be insufficient for a conclusive diagnosis.
Therefore, while biopsy is an important diagnostic tool, it should not be equated with absolute confirmation. If the biopsy result is inconclusive, doctors typically recommend repeating the biopsy, performing complete pathological examination after surgical removal of the lesion, or integrating findings from imaging studies and laboratory tests to ensure diagnostic accuracy.
