Mapping biopsy for Buruli ulcer self-medicated with occlusive dressing

Buruli ulcer: An epidemiological update from Japan

Japan is one of the rare non-tropical countries with documented cases of Buruli ulcer (BU). Mycobacterium ulcerans subsp. shinshuense has been identified as the causative agent. The first report of BU in Japan dates back to 1982, with sporadic reports thereafter. Recently, the number of cases has been on the increase, and 50 cases (57.7%) are from the past decade alone, out of a total of 87 cases reported to date. Japan's well-developed healthcare facilities play a crucial role in enabling detailed investigations and providing appropriate treatment for patients, contributing to a favorable prognosis. However, the rarity of the disease results in lack of awareness among healthcare professionals, leading to frequent delays in diagnosis. This article aims to offer an updated overview of BU cases in Japan and to raise awareness of BU among dermatologists and other healthcare professionals in a non-endemic setting.

Histological and quantitative polymerase chain reaction-based analysis of Buruli ulcer using mapping biopsy method

Background

In Japan, Buruli ulcer cases are often advanced, requiring surgical treatment. However, extensive debridement is often difficult because of cosmetic and functional sequelae. Moreover, the lesions are complicated and composed of edematous erythema, necrotic ulcer, and erythematous skin lesions caused by a paradoxical reaction, which also make it difficult to perform adequate debridement.

Methodology/Principal findings

We performed quantitative polymerase chain reaction (PCR) analysis for IS2404 using 29 samples taken from mapping biopsy. We evaluated the relationship among mycobacterial burden, histopathological findings, and clinical outcomes using 83 tissue samples taken from mapping biopsy and debrided Buruli ulcer. On quantitative PCR, the Cp values of IS2404 amplification were substantially different in each site. The major histological findings could be divided into massive subcutaneous necrosis with scant inflammatory cell infiltration and dense inflammatory cell infiltration. Of the 84 sites, 34 were subjected to repeated histological evaluations. In these sites, histological necrosis did not disappear over time despite standard antibiotic treatment. In contrast, the ulcers were cured and no recurrences were observed without resecting the 11 biopsied sites that lacked histological necrosis. Although quantitative PCR revealed that a lower Cp value of IS2404 was associated with histological massive necrosis, sites that showed lower Cp values clinically did not always need debridement.

Conclusion/Significance

Our descriptive study revealed that the histological findings and amounts of mycobacterial DNA differed according to the sites despite being found in one lesion. Our results showed that the need for surgical debridement in each site was correlated with histological necrosis without inflammatory cell infiltration, as the inflammation is supposed to represent an active host immune response rather than mycobacterial burden. We suggest that the debridement of lesions with histological necrosis in mapping biopsy may be useful for Japanese cases with unsuccessful standard antibiotic treatment to achieve sufficient clinical improvement.

We have proposed a preoperative mapping biopsy procedure to perform optimal debridement for Buruli ulcer presenting complicated skin lesions. Briefly, multiple punch biopsies are performed from various sites around the Buruli ulcer lesions and the range of resection is decided according to the histological findings of the biopsies. Herein, we performed histological examination and quantitative PCR analysis using 83 tissue samples taken from mapping biopsy and debrided Buruli ulcer to validate our method. Our results suggested that the sites with histological necrosis need to be resected during surgical debridement and that the sites without histological necrosis can be preserved. These results in combination with those of previous studies are supportive of the mapping biopsy procedure that we have proposed. However, a randomized controlled study questioned the need for adjunct surgical treatment in Buruli ulcer. Further studies are needed to establish the Japanese evidence for surgical treatment in Japanese cases of Buruli ulcer.