A tumor is an abnormal growth of body tissue, where cells divide and grow excessively. These growths can be noncancerous (benign) or cancerous (malignant). This article explores how tumors appear at different levels, from visible signs to advanced imaging and microscopic analysis, aiding their identification.
How Tumors Appear to the Eye
A tumor’s macroscopic appearance might present on the skin as a raised area, plaque, nodule, or ulcerated mass. External growths vary in color (pale, pink, red, or brownish) and may have visible abnormal blood vessels.
Internal tumors can exhibit a range of appearances. They might be well-defined and encapsulated, or have irregular shapes and fuzzy borders, blending into surrounding tissues. Texture varies from soft to firm or hard. Some may show signs of hemorrhage or necrosis, such as internal bleeding or dead tissue.
Imaging Techniques: Unveiling Tumors Inside the Body
Medical imaging techniques visualize tumors deep within the body non-invasively. These methods offer different “pictures” based on their underlying technology.
X-rays produce shadow-like images where denser tissues, like bone, appear white, while softer tissues appear in shades of gray. Tumors, often denser than surrounding tissue, appear as lighter gray areas or abnormal masses. Small or early-stage tumors can be difficult to detect.
Computed Tomography (CT) scans use X-rays from multiple angles to create detailed cross-sectional images, offering more information on a tumor’s size, shape, and location than standard X-rays. Tumors often appear as localized, irregular masses varying in density compared to healthy tissue. Contrast material can highlight cancerous tissue and enhance the visibility of blood vessels feeding the tumor.
Magnetic Resonance Imaging (MRI) uses powerful magnets and radio waves to generate detailed images of soft tissues. Cancerous tissue appears as a white or very light mass on MRI images, and contrast dye can make tumors stand out more brightly. MRI is effective at showing how deeply a tumor has grown into tissues and and can help differentiate between fluid-filled cysts and solid tumors.
Ultrasound technology uses high-frequency sound waves to create real-time images, especially for fluid-filled areas. On a sonogram, cancer often appears as a dark grey patch (hypoechoic) with irregular or angular edges, contrasting with lighter grey or white healthy tissues. Doppler ultrasound assesses a tumor’s vascular network, revealing irregular blood flow patterns characteristic of malignant growths.
Positron Emission Tomography (PET) scans detect the metabolic activity of cells by injecting a radioactive tracer. Cancer cells, with higher metabolic rates, absorb more tracer and appear as bright spots on PET images. PET scans are combined with CT or MRI (PET-CT or PET-MRI) to provide both metabolic and anatomical information, offering a comprehensive view of the tumor’s location and activity.
The Microscopic Perspective: What Cells Show
Pathologists examine tumor tissue at the cellular level using biopsies, which remove a sample of suspicious tissue. This tissue is prepared by chemically treating or freezing it, slicing into thin sections, and placing on glass slides. Stains enhance contrast, allowing pathologists to study cells under a microscope.
Under microscopic examination, pathologists look for features indicating abnormal cell growth. These include variations in cell size and shape (pleomorphism). Malignant cell nuclei often appear larger, darker (hyperchromatic), and may have an abnormal nuclear-to-cytoplasmic ratio compared to normal cells. Abnormal growth patterns, such as disorganized cell arrangements or numerous atypical mitotic figures (cells undergoing division), provide clues. This microscopic analysis aids in definitive diagnosis, classifying tumor type, and assessing aggressiveness.
Interpreting the “Picture”: Benign vs. Malignant Clues
Visual “pictures” from gross examination, imaging, and microscopic analysis offer clues to distinguish between benign and malignant tumors. However, a definitive diagnosis requires a comprehensive assessment.
Benign tumors often have smooth, regular, well-defined borders, appearing encapsulated and not invading surrounding tissues. They grow slowly and may have a uniform appearance on imaging.
Malignant tumors, in contrast, often have irregular shapes, fuzzy or spiculated borders, and grow rapidly. On imaging, they may show signs of invading adjacent tissues or having an abnormal blood supply. Microscopically, malignant cells display significant abnormalities. Despite these visual indicators, no single “picture” is sufficient for diagnosis; a definitive determination relies on a combination of clinical evaluation, imaging findings, and pathological analysis of tissue samples.