Changes in the size and number of skin lesions in PB leprosy on treatment and follow-up

[[[ Background: ]]] The increase in size of existing skin lesions and appearance of new skin lesions are considered important signs of clinical activity both in untreated and treated leprosy. To confirm such activity, the number and size of lesions need to be recorded methodically prior to therapy and on follow-up, especially in PB leprosy where clinical signs alone define the reactivation of the disease. However, no systematic follow-up studies are available on changes in size and number of skin lesions in PB leprosy before and after therapy. [[[ Objectives: ]]] To measure changes in the number and size of skin lesions in PB leprosy patients before starting MDT PB and after 18 months follow-up in order to evaluate their relevance in assessing clinical improvement and identifying possible relapses. [[[ Design: ]]] In 32 untreated leprosy patients with 1-5 skin lesions, the number of skin lesions were recorded on body charts and their size measured using a grid chart method to arrive at total area of involvement in each patient prior to starting MDT PB and after 18 months. Skin smears and skin biopsies were performed at entry and follow-up to assist the clinical evaluation. [[[ Results: ]]] Twenty three patients had single skin lesion (SSL), followed by three each with two and three skin lesions respectively, two with four and one with five skin lesions. The area of involvement ranged from six to 1686 sq cm. Few patients with SSL had higher areas of involvement than those who had multiple skin lesions. On follow-up at 18 months, in 14 (44%) patients skin lesions were not measurable, while in 18 (56%) they were measurable, with eight (25%) patients showing no change, three (9%) showing decrease and seven (22%) showing increase in area of involvement. Of the seven patients showing increase, in three it was due to the spread of existing skin lesions alone, in one it was due to a new skin lesion alone and in three due to the spread of existing skin lesions and the appearance of new skin lesions. New skin lesions were multiple (> 3) in two patients. T1R was observed in three out of four patients with new skin lesions, and this was persistent at 18 months in one patient. When histopathology at the entry and 18 month follow-up was compared, in one patient with persistent T1R with appearance of multiple new skin lesions, there was increase in GF from 10 to 40% with histological features of T1R and a BI of granuloma of 1+. [[[ Conclusions: ]]] In 32 treated patients of PB leprosy on 18 month follow-up for changes in size and number of skin lesions, of six patients showing increase in area of involvement of existing skin lesions, 3 (50%) developed new skin lesions, indicating persistent disease activity. The new lesions which were associated with T1R increased the total number of skin lesions to > 5 in two of these patients requiring a change of drug regimen from PB to MB MDT, with one of them fulfilling clinical and histopathological criteria for relapse of leprosy. Hence, although new lesions are known to occur as part of T1R in PB patients, they are events of great significance which need to be assessed in a methodical manner for their influence on classification and therapy of leprosy.