Intralesional immunotherapy of cutaneous warts using tuberculin purified protein derivative and vitamin D₃ – A randomized comparative study

INTRODUCTION

Cutaneous warts, caused by the Human Papillomavirus (HPV), represent one of the most prevalent dermatological conditions worldwide. While often considered benign, the impact of these seemingly innocuous growths on individuals’ physical and psychological well-being should not be underestimated. Warts tend to disappear spontaneously, recur after an apparent total clearance, or remain recalcitrant to all therapies. In general, a wart is considered recalcitrant if all the available conventional treatments fail.¹ In healthy individuals, two-thirds of cutaneous warts are often self-limiting and regress spontaneously within 2 years.² The condition may resolve slowly and persist for many years, especially in adults.³ Therefore, the management of cutaneous warts occasionally requires multiple modes of treatment. As cutaneous warts involve host immunity for eradication, immunocompromised individuals exhibit an elevated susceptibility to recalcitrant cutaneous warts, likely due to impaired viral clearance mediated by cellular and humoral immune responses.⁴ Multiple studies have been conducted on the use of immunotherapeutic agents in the treatment of warts. However, there is still a lack of high-quality, Level-1 evidence for the efficacy of this treatment.⁵ Even with the same agent used in different studies, the reported efficacy varies widely, depending on the patient’s age, compliance, and immunocompetence. Mycobacterial antigens have been popular for intralesional treatment of warts. Specific inoculations studied for this purpose include tuberculin purified protein derivative (PPD), Mycobacterium w vaccine, and Bacillus Calmette–Guerin. Of these three modalities, tuberculin PPD is by far the most frequently used for refractory cutaneous warts. The regression of warts from intralesional tuberculin PPD is associated with increased levels of interleukin (IL)-12 and IL-4, which contribute to cell-mediated immune reaction.⁶ Similarly, Vitamin D₃ has numerous effects on cells within the immune system, including inhibition of B-cell proliferation, blocking B-cell differentiation, and immunoglobulin secretion.⁷ Vitamin D₃ additionally suppresses T-cell proliferation and results in a shift from a Th1 to a Th2 phenotype.⁸ Furthermore, it affects T-cell maturation with a skewing away from the inflammatory Th17 phenotype and facilitates the induction of T regulatory cells.⁹ These effects result in decreased production of inflammatory cytokines (IL-17 and IL-21) and increased production of anti-inflammatory cytokines such as IL-10. Despite promising individual results for both, a paucity of studies directly compares the efficacy of intralesional tuberculin PPD and Vitamin D₃ in treating extra-genital cutaneous warts. The present study is undertaken to gather more clinical evidence about the beneficial effects of tuberculin PPD and Vitamin D₃ in cutaneous warts and compare the effectiveness of the two agents in recurrent and recalcitrant warts.

MATERIAL AND METHODS

This prospective, randomized, comparative, and single-blind study was approved by the Institutional Ethics Committee at Era’s Lucknow Medical College and Hospital, Human Research Cell, ERA University, Lucknow, India, and was carried out as per the guidelines of the 1975 Declaration of Helsinki. Written informed consent was obtained from all patients before they participated in the study.

RESULTS

The overall response to treatment

As shown in Table 3, a total of 75.5% of cases in the tuberculin PPD group and 70.7% in the Vitamin D₃ group showed complete resolution of warts. At the 6-month follow-up, complete resolution of warts was achieved in 75.5% (40/53) of patients in Group A (tuberculin PPD) and 70.6% (36/51) of those in Group B (Vitamin D₃). Taking into account both the treatment groups, complete response of the warts after intralesional immunotherapy was observed in 76 out of 104 cases (73.1%). Further, analysis revealed a statistically insignificant difference in treatment response between the two groups (P = 0.402). Analyzing response by wart type [Table 4], verruca plantaris demonstrated the highest complete resolution rate at 81%, followed closely by verruca plana (80%) and verruca vulgaris (77.4%). Notably, no cases of verruca filiformis achieved a complete response. As shown in Table 5, comparing the response of different types of warts to tuberculin PPD (Group A) and Vitamin D₃ (Group B) therapy, it was observed that verruca plana and verruca vulgaris [Figure 1a and b] showed around 94% response following tuberculin PPD therapy. In comparison, verruca palmaris and plantaris showed a 100% response following Vitamin D₃ therapy [Figure 2a and b]. These findings suggest potential morphological specificity in treatment response for these modalities. The response of other clinical types to treatment was varied for the two therapies. The mean time taken for complete resolution of warts was 5.849 ± 0.280 weeks (median 6 weeks) in the tuberculin PPD group and 6.118 ± 0.260 weeks (median 6 weeks) in the Vitamin D₃ group. Data evaluation showed that the time difference in the resolution of warts in the two groups was statistically insignificant (P = 0.552). The patient data showed that there was no recurrence of cutaneous warts after 3 months of intralesional therapy with tuberculin PPD or Vitamin D₃. However, out of 40 patients in Group A and 36 patients in Group B who had achieved complete response at the end of treatment, 7 patients (17.5%) in Group A and 4 patients (11.1%) in Group B reported recurrence of warts at 6 months follow-up.

Table 3: Comparison of the overall response of warts to immunotherapy.

S. No	Outcome	Group A (PPD, n=53)	Group B (Vitamin D3, n=51)	Total (n=104) (%)
1	Complete response	40 (75.5)	36 (70.6)	76 (73.1)
2	Marked response	5 (9.4)	2 (3.9)	7 (6.7)
3	Moderate response	4 (7.5)	4 (7.8)	8 (7.7)
4	Inadequate response	4 (7.5)	9 (17.6)	13 (12.5)
				z=0.893, P=0.402

PPD: Purified protein derivative

Table 4: Complete Response (%) of different types of cutaneous warts to immunotherapy.

Type of wart	No. of cases	No. of cases showing complete response (%)
Verruca filiformis	5	0
Verruca palmaris	8	5 (62.5)
Periungual warts	9	6 (66.7)
Verruca vulgaris	31	24 (77.4)
Verruca plana	30	24 (80)
Verruca plantaris	21	17 (81)
Total cases	104	76 (73.1)

Table 5: Comparison of complete response of different clinical warts to the two types of therapy.

Type of wart	Group A (PPD, n=53)		Group B (Vitamin D3, n=51)		Statistical significance (Fisher exact test) “P” value
	Total No.	No. resolved (%)	Total No.	No. resolved (%)
Verruca filiformis	3	0	2	0	1.000
Verruca palmaris	3	0	5	5 (100)	0.018
Periungual warts	4	3 (75)	5	3 (60)	1.000
Verruca plantaris	11	7 (63.6)	10	10 (100)	0.090
Verruca plana	17	16 (94.1)	13	8 (61.5)	0.061
Verruca vulgaris	15	14 (93.3)	16	10 (62.5)	0.083

PPD: Purified protein derivative

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Figure 1:

(a) A 35-year-old male patient presenting with verruca vulgaris on the dorsal aspect of right great toe. The target lesion is indicated by the black arrow. On the first session (week 0) of treatment with intralesional tuberculin purified protein derivative (PPD). (b) At 6 months follow-up, the warts showed a marked response to treatment with intralesional tuberculin PPD.

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Figure 2:

(a) A 28-year-old male patient presenting with a cluster of verruca plantaris on the left foot. The target lesion is indicated by the black arrow. On the first session (week 0) of treatment with intralesional Vitamin D₃. (b) At 6 months follow-up, the warts showed a complete response to treatment with intralesional Vitamin D₃.

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DISCUSSION

Due to the immune system’s pivotal role in restricting wart proliferation, intralesional immunotherapy has emerged as a potential therapeutic approach for patients with cutaneous warts. Its action is based on the activation of the patient’s immune system, which enhances the recognition and eradication of the virus, leading to the clearance of primary and distant warts. Very few studies have been conducted comparing the efficacy of intralesional tuberculin PPD with intralesional Vitamin D₃ in extragenital cutaneous warts. The characteristic feature of young age observed in most of our patients is in agreement with the study on warts carried out by Berth-Jones and Hutchinson,¹⁰ who showed that more than 54% of their cases were in the young age group of 11–25 years. The high prevalence of cutaneous warts observed in the young age group of our patients seems related to their increased susceptibility to skin trauma secondary to physical activity, the effect of cosmetic procedures, close contact with wart patients, and overcrowding. The majority of patients in our study were male (68.3%), with a male-to-female ratio of 2.15:1. Johnson and Roberts¹¹ showed in their study that cutaneous warts affect more males as compared to females. This seems related to the increasing trend of cosmetic concern among males. According to the study conducted by Liu et al.,¹² males are physically more active compared to females and, therefore, at a higher risk of damage to the stratum corneum that serves as an entry point of HPV. Verruca vulgaris was the most commonly observed wart in the present study (29.9%), followed by verruca plana (28.8%) and verruca plantaris (20.2%). Periungual warts (8.7%), verruca palmaris (7.7%), and filiform warts (4.8%) accounted for the remaining smaller percentage of lesions. Similar results were obtained by Liu et al.¹² and Ghadgepatil et al.¹³ regarding the frequency of verruca vulgaris. Comparing the complete response of our patients in the tuberculin PPD group, our results were in agreement with several studies conducted on the response of cutaneous warts to tuberculin PPD therapy.^14-16 However, the response obtained in our patients was greater than in the study conducted by Shaheen et al.,¹⁷ who reported only a 60% complete response to both target and distant warts with tuberculin PPD therapy. Comparing the response to Vitamin D₃ therapy using the same dosage and time interval of 2 weeks between sessions, our results are in agreement with Kavya et al.,¹⁸ who achieved a 78.6% complete response. However, using a higher dose of Vitamin D₃ and a time interval of 3 weeks between sessions, Raghukumar et al.¹⁹ achieved complete clearance of warts in 90% of patients. The results suggest that there is a direct dose-response relationship between warts and Vitamin D₃. We observed a response of 93.3% and 94.1% in verruca vulgaris and verruca plana, respectively, after tuberculin PPD therapy. The response obtained for verruca vulgaris was 90.9% in the study conducted by Akula et al.,²⁰ which is closer to our results. However, our response for verruca plana was quite higher than that obtained by Fawzy et al.,²¹ Jaiswal et al.,²² and Saoji et al.²³ who achieved a final response of 55%, 60%, and 67%, respectively, at the end of their study. Both verruca palmaris and verruca plantaris showed 100% response to Vitamin D₃ therapy in our study. However, Kavya et al.¹⁸ obtained only 82.6% response to Vitamin D₃ for both these types of warts. Using a higher dose of 0.4 mL Vitamin D₃ at an interval of 3 weeks between sessions, Raghukumar et al.¹⁹ obtained a response of 100% for both verruca palmaris and verruca plantaris. A varied response to Vitamin D₃ has been shown by other researchers such as Shaldoum et al.,²⁴ Abou-Taleb et al.,²⁵ and Aktaş et al.²⁶ in palmoplantar warts who achieved a final response of 40%, 43.5%, and 80%, respectively. The difference in the response of warts to tuberculin PPD and Vitamin D₃ therapy seems related to the individual variations and dose of the drug given. No adverse reactions were observed in patients of both study groups. However, mild pain and swelling at the injection site were observed in three patients with facial warts (5.88%) following Vitamin D₃ therapy. Abou-Taleb et al.²⁵ reported edema and erythema in 9.80% of patients following intralesional Vitamin D₃ therapy and 5.66% of patients following intralesional tuberculin PPD therapy. One of the limitations of our study was the absence of a placebo control group in the study design. A placebo group would have provided a better baseline for comparison.

CONCLUSION

In light of the present study’s findings, intralesional tuberculin PPD and Vitamin D₃ emerge as potential first-line treatments for the management of recurrent and recalcitrant extragenital cutaneous warts, given their evident effectiveness and safety profile. However, further large-scale comparative investigations may be necessary to elucidate potential variations in efficacy across specific wart morphologies.