Introduction:
Coagulative necrosis is caused by accidental injury. It results in enzymatic protein denaturation of tissues. Chemicals such as sulphuric acid, hydrochloric acid, and picric acid are on the list of causative agents. Coagulative necrosis causes inflammation and ischemia. Also, it can be from an infection due to bacterial agents. The lack of oxygen supply (hypoxia) to tissue leads to coagulative necrosis.
What Are the Features of Coagulative Necrosis?
In coagulative necrosis, the primary structural outline of the cell wall is preserved. The chemicals denature the structural and enzymatic proteins inside the cell. It is characterized by the hypoxic death of cells everywhere except for the brain. The foci seen at the early stages are firm, pale, and slightly swollen. Over time, these cells become more yellowish, softer, and shrunken in size. They appear red due to inflammatory reactions.
What Are the Microscopic Characteristics of Coagulative Necrosis?
During the microscopic examination, these cells exhibit very typical outer cellular patterns making them easily recognizable. But the inner cell mass of the nucleus and cytoplasm is wholly lost. Hence they are also called ‘tombstone’ appearances. The necrotized cells appear more swollen in shape than the normal cells. These cells later undergo phagocytic action, where the cells are engulfed by the body's immune cells leaving behind the remains known as granular debris and fragments of cells. The preservation of the outer cellular structure lasts for days. One of the characteristic features of coagulative necrosis is the transition zone between necrotic and viable cells. They lack granulation tissues in between. Protein denaturation gives rise to hydrophobic regions. Death of Sertoli cells, as seen in tubular necrosis of the testis, is also a feature.
What Are the Histopathological Features of Coagulative Necrosis?
Cells exhibit nuclear pyknosis, where the chromatin inside the nucleus shrinks; karyorrhexis, where the nucleus gets destroyed due to dying cells and cytoplasmic condensation, where the cell completely shrinks itself. In addition, cells show a spindle-shaped pattern, sheet-like growth with outer architecture well maintained for a few days, multinucleation and fibrosis, and amyloid deposition.
What Are the Treatments Available for Coagulative Necrosis?
Most of the coagulative necrosis treatments come under cancer therapy. Treatments available are
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Radiofrequency (RF): It is helpful in liver resection surgeries. It prevents the flow of blood within the resection margins.
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High-Intensity Focussed Ultrasound (HIFU): This induces coagulative necrosis in target tumors. These procedures help determine the necrosed area and the treatment of the area's relapse, recurrence, and regression. In long-term imaging, HIFU treatment is combined with the following.
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Radionuclide Imaging (RI): In this, radioactive sensors are used to detect the metabolic activity of tumor cells. It is a highly sensitive procedure and is more precise in diagnosing the condition.
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Positive Positron Emission Tomography (PET): This is used mainly in pancreatic cancer. This is used along with HIFU. This is also used to distinguish between benign and malignant tumors, early detection of tumor sites, staging and prognosis of the tumor, the evaluation of tumor effect, the evaluation of residual foci, and the early detection of recurrence after the treatment. PET scans during clinical practice are less advantageous due to their expensive cost.
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Digital Subtraction Angiography (DSA): This provides an image of blood vessels in the brain. A catheter is inserted into a leg artery, following it up to the brain. It reflects tumor blood vessels. The tumor is reflected using a dye mechanism. A general evaluation of tumor vessels is appreciated, not the nutrient vessels, so the blood supply to tumor cells is not visible. DSA is useful in treating embolisms and helps detect multiple lesions, local metastasis, and residual lesions. This helps in the control and elimination of lesions.
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Ultrasound-Guided Interstitial Laser Photocoagulation: This is used for solid, solitary, benign non-functioning thyroid nodules.
What Are the Commonly Encountered Types of Coagulative Necrosis?
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In Fungal Infection: The histopathology of fusariosis, a fungal infection seen in plants and animals, and the fungus named aspergillosis show an identical aggressive form of coagulative necrosis. Infarction of blood vessels, hemorrhage, and necrosis of blood vessels are seen. The Fusarium shows separation at the branching sites, similar to that of Aspergillus.
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In Bacterial Infection: During coagulative necrosis, large intralesional bacterial colonies are absent in bacteria yersiniosis. In animals, the inflammatory infiltrates are more grainy in appearance. The lymph nodes appear hyperplastic showing abnormal multiplication of cells, and increased neutrophil counts are seen. Necrosis of lymph node foci happens. In hemorrhagic conditions, where blood flows out of the vessels and infections are caused due to bacteria in ulcerative necrotizing enteritis, infection is passed from the oral route through submandibular lymph nodes.
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In Mushroom Poisoning: A.phalloides poisoning may lead to massive liver cell necrosis. This appears as ballooning degeneration of the lobule, forming a mushroom appearance. In human liver cell necrosis, only a few periportal hepatocyte cells are preserved; the rest undergo coagulative necrosis. In liver cell necrosis, cells like Kupffer cells engulf the foreign particles, and myofibroblasts cells help the tissue regain its normal structure. The presence of endothelialitis of terminal hepatic veins can also be seen.
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In Thyroid Nodules: The chemical coagulative necrosis of ethanol causes small vessel thrombosis. This leads to fibrosis and permanent ablation of tissues. A single administration of ethanol in thyroid cysts reduces the recurrence to up to twenty percent. At the same time, multiple injections of ethanol are used to cure stimulating thyroid hormone (TSH). Around sixty to seventy percent of the population having toxic nodules can be fixed this way, and seventy to eighty percent can be treated for hot nodules. Additional injections are of little effect. Ethanol injection is an alternative treatment option for patients who do not want to undergo radioiodine treatment or surgery. Repeated treatment is advised for a complete cure. Long-term side effects are still unknown.
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In Male Reproductive System: Coagulative necrosis is best observed in the tubular cells of the testis. Disruption of Sertoli cells lining the tubule is noted. The blood-testis barrier is inflamed due to inflammatory infiltration. Necrosis of large areas can be seen as infarction of the testis.
Conclusion:
Coagulative injury can also be induced due to high local temperatures. The chances of regeneration are high in coagulative necrosis. Coagulative necrosis occurs mainly in bodily organs and can cause systemic conditions like myocardial infarction. Labile cells adjacent to the necrotized tissues help replicate new cells through mitosis.
