What does a tumor look like in a rat? - briefly
In a rat, a tumor presents as a localized, firm, irregular mass that may be palpable under the skin or within an organ. Macroscopic inspection often shows discoloration, ulceration, or necrotic regions depending on the tumor type and stage.
What does a tumor look like in a rat? - in detail
A tumor in a laboratory rat can be identified by several macroscopic characteristics. Visible masses are typically firm to rubbery, range from a few millimeters to several centimeters in diameter, and may distort surrounding tissue. Surface texture varies: some neoplasms are smooth, while others exhibit irregular, ulcerated, or necrotic areas. Coloration differs according to tissue type and vascularity; common hues include pale gray, pinkish, or hemorrhagic red. Borders may be well‑defined, indicating encapsulation, or infiltrative, merging with adjacent structures.
Microscopic examination reveals cellular architecture. Malignant lesions often display pleomorphic cells, high nuclear‑to‑cytoplasmic ratios, prominent nucleoli, and frequent mitoses. Necrotic cores, angiogenesis, and stromal desmoplasia are frequent features. Benign growths tend to retain organized glandular or stromal patterns, possess uniform nuclei, and lack invasive fronts.
Imaging modalities corroborate physical findings. Ultrasound shows hypoechoic or heterogeneous echotexture; MRI provides T1‑weighted hypointensity and T2‑weighted hyperintensity, reflecting water content and cellular density. Computed tomography highlights calcifications or bone involvement when present.
Key descriptive parameters for documentation include:
- Size (maximum dimension in millimeters)
- Location (organ, subcutaneous, intraperitoneal, etc.)
- Consistency (firm, soft, cystic)
- Surface (smooth, ulcerated, necrotic)
- Color (pale, pink, hemorrhagic)
- Border definition (encapsulated vs. infiltrative)
- Histopathological grade (cellular atypia, mitotic index)
- Vascular pattern (presence of neovascularization)
These criteria enable consistent assessment, comparison across studies, and accurate classification of rat tumors.