Zoon's Balanitis Treated with Erbium:YAG Laser Ablation

INTRODUCTION

Zoons balanitis (ZB), also known as plasma cell balanitis, is a relatively uncommon, idiopathic inflammatory condition. ZB primarily affects the glans penis in uncircumcised males, who present with red-orange, smooth or eroded plaques.^1-10 ZB occasionally causes pruritis or discomfort. CO₂ laser ablation of ZB is an effective treatment¹¹ and may be preferable to circumcision^10,12,13 in the management of this disease. We present a case illustrating that superficial laser ablation with a newer generation of resurfacing lasers may be as effective as traditional continuous-wave CO₂ ablation, with less morbidity, thermal damage and risk of scarring.

CASE REPORT

The Urology department referred a 67 year-old Caucasian male for treatment of squamous cell carcinoma in-situ or erythroplasia of Queyrat (EQ) of the glans penis. He was clinically diagnosed with EQ in 1988 and treated with 5-fluorouracil cream (5-FU). Local recurrence in 1991 was biopsied and showed EQ. CO₂ laser ablation was performed, and repeated in 1993 for another local recurrence. Following these procedures, he was treated twice more with 5-FU topically and appeared to clear completely. His presenting eruption evolved for several months prior to his Urology evaluation. Examination revealed a 23 x 17 mm smooth, brick-red, perimeatal plaque (Figure 1). His medical history and cutaneous examination were otherwise unremarkable.

The clinical differential diagnosis included plasma cell balanitis/Zoons balanitis (ZB), psoriasis, and candidiasis, in addition to EQ. Shave biopsy was consistent with ZB, showing characteristic histologic features of a thinned, effaced epithelium overlying a dense, lichenoid plasma cell infiltrate, telangectasias and hemosiderin deposition. The patient failed 5 months of topical treatment with potent corticosteroids and mupirocin ointment. After the patient requested alternatives to circumcision, we treated the balanitis with Er:YAG laser ablation (Derma-K, ESC Sharplan, 2940 nm, 350 ms).

After EMLA application and local infiltration of 1% plain lidocaine, we treated the balanitis with 3-6 overlapping passes using the lowest power settings (0.5 J/cm²; 3 mm spot size; 5 Hz) (Figure 2,3). He healed well and completely reepithelialized within one week. A confirmatory shave biopsy after 2 months showed no residual balanitis. At 4 months, his exam revealed a perimeatal erythematous smooth plaque, which was retreated with 2 more passes of ablation (same settings). The plaque resolved and one month later a biopsy of the residual perimeatal erythema showed no evidence of ZB (Figure 4). He remains disease free after more than 2 years follow-up.

DISCUSSION

The exact etiology of ZB is unknown, but heat, friction and poor hygiene are considered pathogenic factors.^6,7 Irritation by smegma, urine or external contacts and normal colonizing organisms that become pathogenic under favorable host conditions may also play a contributory role.^14,15 The proclivity of ZB for the uncircumcised and the consistent response to circumcision lend support to this theory.^6-8,12 In one case, incomplete circumcision cleared the majority of ZB, but resulted in persistent disease in the area of glans and prepuce still covered by foreskin.¹² Chronic infection with mycobacterium smegmatis has been postulated as the cause of ZB.¹⁵ Recent attempts to isolate m. smegmatis have been unsuccessful.⁸ Yoganathan et al. conclude that trauma is most significant in the pathogenesis of plasma cell balanitis and vulvitis.⁸ They noted a concentration of disease on the dorsal glans penis, where foreskin friction is greatest. One of their female patients developed plasma cell vulvitis circumferentially around her vulva immediately after a traumatic vaginal delivery.

The unclear etiology of ZB and the multiple contributory factors make it difficult to find specific therapeutic targets. Promotion of good hygiene is an easy and potentially beneficial measure. Patients should be instructed to retract the foreskin regularly and perform gentle cleansing of the entire glans, preputial sac and foreskin. Many local, topical therapies have been reported, but rarely provide more than temporary control. Mid-potency and high-potency topical corticosteroids have been used for many years as a first line measure, producing variable clinical improvement but rarely long-term cures.⁸ Topical antimicrobial preparations including antibacterial and antifungal creams have largely proven ineffective. Fusidic acid is a combination anti-inflammatory and antibiotic agent sharing a similar molecular structure with corticosteroids. Fusidic acid 2% cream has induced both suppression and 6 month cures in 5 of 8 patients, despite an unclear mechanism of action.¹⁶ Radiotherapy and local destructive modalities, such as electrosurgery, have rarely proven effective.

Circumcision has proven the most consistently effective, long-term cure for ZB.^7,10,12,13 In 1984, Ferrandiz and Ribera reported cures in seven consecutive patients undergoing circumcision for ZB, with an average follow-up of 12 months.¹² Murray et al cured five consecutive patients with circumcision, two of whom had previously failed a dorsal slit procedure.⁷ Urologists may regard circumcision as the treatment of choice.¹⁷

In 1989, CO₂ laser ablation was reported as an effective alternative to circumcision.¹¹ They used the defocused mode of the continuous wave CO₂ laser at an irradiance of 200W/cm² to produce highly precise vaporization and selective damage of the target area [ZB]. (Baldwin HE, Geronemus RG, p.493) The continuous wave CO₂ laser, however, carries a significant risk of scarring because its prolonged tissue dwell-time causes collateral thermal damage (200-300 mm).^18,19 Irradiation of the skin surface by the Er:YAG laser produces relatively pure ablation with minimal thermal damage.^19-24 Because ablation is directly proportional to fluence, the Er:YAG laser can be finely adapted to the clinical scenario. Several studies demonstrate that superficial cutaneous wounds produced by the Er:YAG laser or cold steel surgery reepithelialize at equivalent rates and without scarring.^25-27

Ablation depth varies with laser and tissue properties, but with the short-pulsed (~100-300 µs) Er:YAG laser above the ablative threshold (~1.5 J/cm²), single impacts generally ablate 5-50 µm with residual thermal damage measuring 5- 40 µm.^19-25,28-35 These ablation and coagulation depths apply for typical dermatologic settings (1-10 J/cm²). While the fluence (0.5 J/cm²) used in our patient is below the standard ablation threshold for keratinizing human skin, it approaches the range for guinea pig skin (0.6-1.5 J/cm²).²⁰ This fluence and the highly overlapping pattern appeared sufficient to superficially ablate mucosal epithelium, which lacks a hydrophobic orthokeratotic stratum corneum, which may have a slightly higher water content due to increased intracellular glycogen, and which may possess slightly weaker structural integrity than typical epidermis. Our mechanical wiping may also have contributed to the removal of some thermally denatured, non-vaporized, epithelium. While our clinical and pathological results confirm the efficacy of our parameters and technique, using a definitively ablative fluence may prove more efficient for treating this process.

The Er:YAG laser emits energy in the mid-infrared invisible light spectrum with a wavelength of 2940 nm, which corresponds closely with an absorption peak for water.³⁶ The peak water absorption coefficient is 13 times greater for the Er:YAG than for the CO₂ laser.^20,37 Epidermis is composed of approximately 70% water by volume, making it highly susceptible to ablation with the Er:YAG laser.²¹ Because epidermal ablation is so efficient, peripheral thermal damage is limited to a very narrow zone. Recent work has shown that repetitive Er:YAG laser irradiation with pulse-stacking of low fluences can cause deep coagulation of dermal collagen.³⁸ When treating ZB, proper technique should prevent this effect and scarring is unlikely because bleeding serves as a safeguard against deep ablation. Despite the highly vascular penile tissue, our negligible intra-operative bleeding demonstrates the precise and superficial ablation possible with the Er:YAG laser. ZB represents an epithelial process and the glans penis lacks adnexal structures that might harbor residual disease and that contribute to reepithelialization. Deep ablation is neither necessary nor desirable. The focal perimeatal recurrence likely resulted from mild urethral extension and it was easily retreated. Finally, smoke evacuation and properly fitted and filtered masks are critical in this setting because of the significant plume produced and the risk of subclinical pathogenic microorganisms on genital skin.

CONCLUSION

As an alternative to definitive circumcision, we propose a trial of Er:YAG laser ablation as a low risk, first line treatment of ZB, replacing the far more thermally destructive CO₂ laser. The Er:YAG laser is ideally suited to selectively remove the diseased epithelium of the glans penis without risk of scarring. We also emphasize the need for histologic confirmation of clinical diagnoses, as this patient was referred for Mohs micrographic surgery of EQ that was subsequently diagnosed as ZB pathologically.

Address Correspondence to: Maj John G. Albertini
Dept of Dermatology
 Brooke Army Medical Center
Fort Sam Houston, TX 78234
Phone (210) 916-4408; FAX (210) 916-3103
 John.Albertini@cen.amedd.army.mil

Transfer of copyright statement: I (we), the undersigned author(s), was (were) an employee(s) of the US federal government when this work was conducted and prepared for publication; therefore, the work lies within the public domain and is not subject to the Copyright Act. Ownership of copyright cannot be transferred.

Reprints not available

Accepted 6 December 2001.

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