Successful Treatment of Plantar Mosaic Warts With Intralesional Bleomycin: A Case Report and Review of Literature

ABSTRACT

Intralesional bleomycin is an effective and safe treatment option for plantar mosaic warts that are resistant to conventional therapies. This case highlights the importance of targeted intralesional therapy, even in recalcitrant and extensive plantar wart variants, with rapid resolution observed after just two treatment sessions and no recurrence during follow‐up of 6 months.

1. Introduction

Human papillomavirus (HPV) is a double‐stranded DNA virus with more than 200 recognized genotypes, broadly classified into mucosal and cutaneous types. Cutaneous HPV strains infect keratinized epithelium and cause warts at various anatomical sites with distinct clinical morphologies [1]. Palmoplantar warts are typically associated with HPV types 1, 2, 4, 27, and 57 and occur in palms and soles [2]. A mosaic wart is a form of plantar wart appearing as confluent plaques of multiple verrucae creating a “cobblestoned” appearance typically on weight‐bearing areas of the foot [3]. There are many different treatment options for plantar warts, but none have been consistently effective for all patients. It is common for the condition to require several destructive procedures, and recurrences often occur [4, 5, 6]. Clinically, plantar mosaic warts should be differentiated from corns, calluses, porokeratosis plantaris discreta, and foreign body granulomas. The presence of pinpoint thrombosed capillaries on paring or dermoscopy supports the diagnosis of mosaic warts [7].

Standard treatment options—such as cryotherapy, topical keratolytics, laser ablation, and surgical excision—have shown inconsistent effectiveness and are frequently associated with recurrence, pain, scarring, and lengthy treatment durations. These challenges have long been a source of frustration for both patients and healthcare providers [8, 9]. Also, cryotherapy may not be easily available everywhere [10].

In this scenario, intralesional bleomycin has emerged as an effective option for recalcitrant warts due to its antiviral and cytotoxic properties [8]. This case report describes the clinical course and successful treatment of mosaic plantar warts in a 19‐year‐old man using intralesional bleomycin.

2. Case Presentation

A 19‐year‐old immunocompetent male presented to the dermatology outpatient department with complaints of multiple hyperkeratotic lesions over the plantar aspect of the right foot for over 8 months. The lesions were progressively increasing in size and number, with discomfort during walking. There was no history of similar lesions elsewhere on the body, no prior systemic illness, and no significant drug or family history. The patient had previously received several unsuccessful therapies: topical salicylic acid 20% solution applied daily for 6 weeks, two sessions of cryotherapy at 2‐week intervals, one session of intralesional Measles, mumps and rubella (MMR) vaccine and 1 session of electrocautery, all with no clinical improvement.

On clinical examination, multiple > 50 coalescing hyperkeratotic papules and plaques of size ranging from 0.1 cm × 0.1 cm to the largest coalescing plaque of 4 cm × 4 cm, asymmetrically distributed over the plantar surface of the right forefoot, extending from the base of the second toe to the medial arch, forming a classic mosaic wart pattern, grayish to whitish in color, surface appears verrucous with normal surrounding skin. The lesions were firm, nontender, and exhibited pinpoint black dots on paring. Several smaller satellite lesions were observed on the periphery and lateral aspects of the sole (Figure 1).

FIGURE 1.

Baseline presentation showing multiple confluent hyperkeratotic papules and plaques (mosaic warts) on the plantar surface of the right forefoot.

A clinical diagnosis of mosaic plantar warts was made.

3. Treatment

After informed consent, the patient was initiated on intralesional bleomycin injection therapy due to the recalcitrant nature of the warts and failure of prior treatments.

Bleomycin injection (15 mg) was reconstituted with 15 mL of normal saline to prepare a 1 mg/mL solution (=1 Unit/mL). After careful paring of hyperkeratotic lesions, topical anesthesia (5% lidocaine) cream was used for anesthesia. A 27‐gauge insulin syringe was used to deliver intralesional injections in multiple small deposits until blanching of the lesion was observed. Injections were placed intradermally at a depth of 2–3 mm, spaced across the mosaic plaque and satellite lesions.

Session 1 (Day 0): Approximately 2.0 mL of the solution (≈2.0 mg) was injected into the central cluster of the mosaic wart.

Session 2 (Day 14): A further 0.8 mL (≈0.8 mg) was injected into residual peripheral and satellite lesions.

The total cumulative dose administered was 2.8 mL (≈2.8 mg).

Postprocedure, the treated areas were dressed with sterile gauze. The patient was advised to limit weight‐bearing for 24 h, keep the site clean and dry, and monitor for signs of secondary infection. Oral ibuprofen 400 mg was prescribed as needed for pain control.

Notable eschar formation was observed in treated areas after 4 days (Figure 2). Patient complained of significant pain, rated 7/10 on the visual analogue scale, which gradually subsided within 1 week with ibuprofen 400 mg taken twice daily as required. No local infection, ulceration, or neuropathic symptoms were observed.

FIGURE 2.

Day 4 after the first intralesional bleomycin injection demonstrating eschar formation and necrosis over injected central lesions.

At 2 weeks the crusted eschar was gently debrided (Figure 3) and remaining peripheral and satellite lesions were injected. The patient reported significant improvement, with no adverse effects and complete eradication in 6 weeks (Figure 4). No infection, ulceration, dyspigmentation, scarring, or functional impairment was observed.

FIGURE 3.

Two weeks after the initial injection: Crusted eschar debrided, revealing partial healing and reduction of lesion size before the second bleomycin session (0.8 mL injected into peripheral and satellite lesions).

FIGURE 4.

Six weeks after treatment initiation showing complete clinical clearance with restoration of normal skin texture and color, without scarring or dyspigmentation.

On follow up at 3 and 6 months, the patient remained lesion‐free with no evidence of recurrence.

4. Discussion

It is estimated that 40% of the population is infected with HPV; among such 7%–12%, develop a wart [11, 12]. Plantar warts account for a substantial subset, with an estimated annual incidence of 14% in the general population. They are often persistent and resistant to standard therapies, particularly when they present as mosaic lesions [13, 14].

Bleomycin was originally isolated from the actinomycotic soil fungus Streptomyces verticillus [15]. Bleomycin possesses antitumor, antibacterial, and antiviral properties. It binds DNA and induces strand breaks, triggering apoptosis and localized tissue necrosis. The enzyme bleomycin hydrolase, which deactivates bleomycin, is present throughout the body but exists in only minimal quantities in the skin. As a result, when bleomycin is injected directly into a lesion, a high concentration of the active drug remains at the site, making even a small dose effective for treating warts [15, 16].

Bleomycin is administered in small intradermal deposits until blanching is achieved, with a recommended maximum of approximately 2 mL per session [17]. Bleomycin is available as 15 mg powder form and reconstituted as 1 mg/mL (=1 Unit/mL) although lower strength preparations 0.5 mg/mL or 0.1 mg/mL may also be effective [17, 18, 19].

When compared with other treatment modalities, intralesional bleomycin offers certain advantages. Conventional destructive methods such as cryotherapy and electrocautery remain widely used but often require multiple sessions and carry a higher risk of pain, scarring, and recurrence [20]. Topical keratolytics like salicylic acid are inexpensive and accessible but are less effective for thick, hyperkeratotic lesions and demand prolonged patient compliance [9]. Laser ablation provides rapid clearance but is costly, operator‐dependent, and less available in resource‐limited settings [21].

Intralesional immunotherapies, including Candida antigen and MMR vaccine, have gained interest for their ability to induce a systemic immune response and treat distant lesions, yet they may require several sessions and demonstrate variable efficacy across studies [22]. In contrast, bleomycin acts directly through cytotoxic and antiviral mechanisms, often achieving clearance within one or two sessions.

Several randomized controlled trials have consistently demonstrated that intralesional bleomycin is an effective treatment for various types of warts, including plantar warts. A study conducted at the Jinnah Postgraduate Medical Centre in Karachi involving 154 patients showed that bleomycin had a significantly higher clearance rate (94.8%) compared to cryotherapy (74%) after 6 weeks [23]. Similarly, a randomized controlled trial from Minia University Hospital in Egypt on plantar warts reported a cure rate of 69.3% with minimal and tolerable side effects following bleomycin treatment [24]. Another comparative study involving 60 patients with plane warts found that bleomycin achieved an 85% complete response rate, outperforming Candida albicans antigen (60%) and 5‐fluorouracil (45%), while also requiring fewer treatment sessions [25]. Additionally, a clinical trial at Bouali University Hospital observed an 87.6% clearance rate with bleomycin compared to 72.3% with cryotherapy in common warts [26]. Supporting these findings, a study from Bangabandhu Sheikh Mujib Medical University in Dhaka reported clearance rates of 97% in warts treated with bleomycin, significantly higher than those treated with cryotherapy (82%) [27]. Overall, these studies indicate that intralesional bleomycin is more effective than cryotherapy and other treatment modalities, with favorable safety and efficiency profiles in wart management.

Common adverse effects noticed are injection site erythema, induration, and pain, most of which do not warrant discontinuation of treatment [28]. Transient dyspigmentation can be seen in some cases which gets cleared in some weeks [29, 30].

The more serious complications such as digital ischemia, nail dystrophy, or flagellate hyperpigmentation are rare but recognized [31, 32, 33]. Therefore, its use is contraindicated in individuals with significant peripheral vascular or connective tissue disease.

Treatment is not recommended for children, pregnant women, immunosuppressed patients because of the chance of systemic absorption [30].

This report is limited by its single‐patient design, which precludes generalization of outcomes to broader populations. Histopathological confirmation was not performed, as the clinical and dermoscopic findings were deemed sufficient for diagnosis. The follow‐up duration of 6 months, while adequate to assess short‐term efficacy, may not fully capture late recurrences. In addition, intralesional bleomycin use for warts remains an off‐label indication, and standardized protocols regarding optimal concentration, dosing intervals, and cumulative dose limits are lacking. Further prospective studies and controlled clinical trials are warranted to validate the safety, reproducibility, and long‐term efficacy of this therapeutic approach, particularly in mosaic wart subtypes.

5. Conclusion

Intralesional bleomycin demonstrated rapid and complete clearance of extensive plantar mosaic warts in this patient, with only transient local pain and no recurrence during 6 months of follow‐up. This outcome supports bleomycin as a valuable therapeutic option for recalcitrant plantar wart variants unresponsive to conventional modalities. Nevertheless, given the off‐label nature of its use and the absence of standardized treatment protocols, further controlled studies with larger cohorts and longer follow‐up are needed to establish optimal dosing parameters, evaluate long‐term safety, and confirm its role within the therapeutic hierarchy for mosaic warts.

Author Contributions

Shivendra Kumar Jha: conceptualization, data curation, formal analysis. Amrit Neupane: investigation, writing – original draft. Anisha Basukala: software, writing – review and editing. Aashish Neupane: supervision, writing – review and editing.

Consent

Written informed consent was obtained from the patient's parent to publish this report in accordance with the journal's patient consent policy.

Conflicts of Interest

The authors declare no conflicts of interest.

Neupane A., Jha S. K., Basukala A., and Neupane A., “Successful Treatment of Plantar Mosaic Warts With Intralesional Bleomycin: A Case Report and Review of Literature,” Clinical Case Reports 13, no. 11 (2025): e71467, 10.1002/ccr3.71467.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.