**5.1 Coagulative necrosis**

Coagulative necrosis, is due to hyperthermia (85-100°C) generated in the focal point.

Elementary lesion has ellipsoidal shape. The short length of the shot limits heat diffusion around the focal point. Shot by shot, it is possible to generate a plethora of elementary lesions until all prostate tissue is destroyed.

Coagulative necrosis is a non-reversible phenomenon (Fig. 5).

Fig. 5. On the left, pre-HIFU histology aspect; on the right, post-HIFU histology change

This kind of lesion can be clearly seen on optical microscopy. Its effectiveness in cancer treatment is demonstrated by the absence of cell functional structures, such as membranes, active nuclei, and organelles.

After the treatment, glandular structures cannot be seen any longer, thus demonstrating that the HIFU technique provides a lack of function in the treated prostate.

Also liquefactive necrosis and apoptotic necrosis are reported as a common consequence of HIFU treatment (see § 6.1), but these kinds of necrotic lesions do not affect the whole amount of necrotic areas.

High-Intensity Focused Ultrasound (HIFU)

mechanical damage.

**6.1 Light microscopy** 

**6. HIFU-induced histopathological changes** 

immunoistochemistry and electron microscopy.

the striated sphincter and vasculo-nervous bundles.


This difference allows to surely set the treatment outlines and save the prostate apex, and

Fig. 6. Elementary lesion formation and its effects on prostate parenchyma, due to heat and

HIFU-induced histopathological changes can be studied thanks to light microscopy,

At light microscopy, we can say that the prostatic structure is completely disrupted and

hardly recognizable. Three different types of cellular necrosis are generally found:
