Persistence of skin lesions after completion of treatment in paucibacillary leprosy: prevalence and its clinicopathological associations

Background: Leprosy is a chronic infectious disease caused by Mycobacterium Leprae. It usually affects skin and nerves. Diagnosis of leprosy is mainly clinical, however diagnosis can be confirmed by identification of bacilli and by finding of characteristic histopathological features. Persistence of skin lesions after completion of treatment is a great anxiety to the patient and the family. There were hardly any studies on persistent skin lesions.

Objectives: The main objective was to determine the histopathological changes of skin lesions after completion of 6 months multi drug treatment (MDT) in patients with paucibacillary (PB) leprosy. Other specific objectives were to determine the prevalence of persistent lesions after completion of treatment, to determine the association between persistent lesions and active granulomata in PB leprosy, and to determine the factors associated with persistent lesions.

Method: This study was carried out on a cohort of 77 patients with biopsy confirmed tuberculoid leprosy who have completed 6 months PB treatment, attending Colombo South Teaching Hospital from July 2012 to July 2013.Data was collected from interviewer administered questionnaire. Four mm size punch biopsies were performed, pre treatment and post treatment. Histology findings were compared.

Results: The study sample consisted of 77 patients, 57.1% were females. Age ranged from 6.5 years to 76 years and the mean age was 33.92 years (SD =18.62 years) with the median of 33 years. Most (42.9%) patients sought treatment after 1 to 2 years of the onset of the disease. Twenty one patients (24%) did not have persistent skin lesions after completion of treatment, whereas fifty six patients (73%) had persistent skin lesions. Small minority of 52% had type l reaction. Furthermore, most (54.5%) patients' drug regime had to change over to MDT (MB) without dapsone due to dapsone induced side effects. Interestingly, 17 (22.1%) patients who had persistent hypopigmented patches had persistent granulomata in the post treatment biopsy which is statistically significant. However, majority had resolving histological features such as basal hyperpigmentation plasmacytoid cell infiltrate and sclerosis of the dermis even though they had persistent skin lesions.

There was no significant association between Persistent skin lesions and drug regime, type I reaction, comorbidities, and type of initial lesion.

Conclusion: In our study population, prevalence of persistent skin lesions was high. We should pay attention to this fact as some had active granulomata, even after completion of treatment. That may imply slowly resolving disease or drug resistance. ln fact, two patients who had active granulomata in the post treatment biopsy developed new lesions on follow up. Hence, persistent skin lesions after treatment need to be followed up regularly to detect resistant cases. Further studies should be done involving larger samples to identify risk factors which could contribute to persistent skin lesions. In contrast, we can convince patients that skin lesions will disappear with time, even though it does not happen just after completion of treatment.