Laser treatment of penile lesions began in the 1980s. Laser phototherapy has been applied to both benign and malignant penile lesions. Over the intervening decades, many studies have been published about laser therapy, and a general consensus has developed about which diagnoses can be successfully treated by laser energy. This chapter covers the areas that have stood the test of time.
Laser phototherapy can be one of the most effective and time-efficient forms of treatment for benign or malignant penile lesions. Laser therapy is most commonly performed in the operating room. The techniques, however, can be used in an office setting when appropriate laser safeguards and patient anesthesia are established. Benign penile lesions such as condylomata acuminata are commonly treated with laser therapy. Unlike conventional topical treatments such as podophyllin, benign penile lesions often respond to a single session of laser therapy. Several different types of lasers may be used for penile surgery. The choice of laser is determined by the disease process and the required depth of coagulation ( Fig. 134.1 ).
Choice of Laser
The most common laser used in penile surgery is the carbon dioxide (CO 2 ) laser. This is a continuous wave laser delivering an invisible beam of infrared 10,600-nm energy from a handpiece. The CO 2 infrared wavelength is strongly absorbed by most types of glass, so a traditional glass optical fiber is not used. The CO 2 laser incorporates an articulating arm and handpiece that directs the beam through air. The beam may be tightly focused to produce a cutting effect, or it may be defocused to produce superficial coagulation over a wider field. CO 2 laser energy is very strongly absorbed by water in tissue. Because of this, the CO 2 laser produces a very superficial lesion (<1 mm), which is ideal for diseases such as condyloma acuminata and erythroplasia of Queyrat. Any protective laser eyewear with either glass or plastic lenses are sufficient for protection from CO 2 laser light.
The neodymium:YAG (Nd:YAG) laser was formerly the most commonly encountered urologic laser. Only the holmium:YAG laser is now used more often. The Nd:YAG laser operates in continuous wave mode, producing an invisible 1064-nm beam and resulting in a deep zone of coagulation reaching 8 to 10 mm. Of all commonly available urologic lasers, the Nd:YAG produces the deepest treatment zone. Similar to the potassium–titanyl–phosphate (KTP) laser, the Nd:YAG laser produces too great a tissue defect to be useful for superficial benign disease. The Nd:YAG laser is useful when a penile cancer is treated using a phallus-sparing technique. The added depth of the Nd:YAG laser coagulation produces a safety zone of coagulation whereby minimally invasive lesions may be safely managed. Use of the Nd:YAG laser requires wavelength-specific protective eyewear. Clear lenses are available but must be specific for Nd:YAG laser use.
KTP lasers are actually Nd:YAG lasers that pass the coherent laser beam through a potassium-titanyl-phosphate frequency-doubling crystal. The invisible 1064-nm Nd:YAG energy is frequency doubled to the brilliant green 532-nm light associated with the KTP laser. The KTP laser produces a middepth of coagulation. KTP lasers do use an optical fiber that can be mounted inside a handpiece or passed through an endoscope. The KTP laser produces about 4-mm depth of tissue coagulation. This is often too deep for condyloma acuminata and erythroplasia of Queyrat but is very useful for extremely superficial squamous cell carcinomas (SCCs) or other more concerning lesions. KTP laser light requires wavelength-specific eyewear.
The holmium laser, although the most commonly used laser for endoscopic treatment in urology, is not particularly suited for skin lesions of the penis. Holmium laser is a 2070-nm pulsed laser with a very prominent high-energy pulse. Holmium energy is very rapidly absorbed in tissue and does not lend itself to a painting motion. The same characteristics that make this laser useful for urologic stone surgery limit its usefulness when treating penile surface lesions. In most cases, lesions that could be treated with a holmium laser could be better treated with a CO 2 laser.
Penile condylomata is optimally treated using the CO 2 laser. Because CO 2 energy is strongly absorbed, it is concentrated in a very thin section of tissue. One should begin treatment with a low energy setting. For treatment of penile condylomata, 5 W is a safe initial setting. Depending on the tissue effect, wattage can be increased as needed. Rarely is more than 10 W required. The CO 2 laser energy is directed by a laser handpiece, and the beam is slightly defocused by withdrawing the handpiece 1 to 2 cm such that the beam is a circle instead of a pinpoint. A painting motion is performed, leading to coagulation of the condylomata. Slight overlapping of the edges of the lesion ensures complete coverage. When the lesion appears to be thoroughly coagulated, it can be “wiped off” using a dampened 4 × 8 sponge. Because of the superficial depth of coagulation, the lesion shears off the deeper tissue, leaving structurally intact dermis. Care should be taken to leave viable skin bridges between larger areas of treatment. Treatment should be limited to areas smaller than 1 cm in diameter because this markedly increases the rate of healing and should eliminate the possibility of large areas of necrotic skin that could require skin grafting. If the lesions are particularly large, skin bridges of condylomata containing tissue should be left untreated. Elective return to the operating room should be planned after the originally treated areas have regrown normal epithelium.
Condylomata such as these are optimally treated with a CO 2 laser ( Fig. 134.2 ). Careful control of the laser beam avoids injury to the urethral meatus. The penile skin is placed on mild stretch to eliminate skin folds. The defocused aiming beam is placed on the side of the lesion. Care is taken to treat the lesion base; however, 1 mm or less of overlap into normal skin is necessary. A painting motion is performed, thoroughly covering an individual lesion ( Fig. 134.3 ). The beam motion is rapid enough to avoid char formation on tissue. After treatment, the lesion may be “wiped off” with a gauze sponge, leaving intact living dermis.