Diagnostic Value of Histological Analysis of Punch Biopsies in Suspected Cutaneous Buruli Ulcer: A Study on 32 Cases of Confirmed Buruli Ulcer in Cameroon

BACKGROUND: Buruli ulcer (BU) is a cutaneous infectious disease caused by Mycobacterium ulcerans. In this prospective study, we aim to clarify the main histopathological features of cutaneous BU based on 4-mm skin punch biopsies and to evaluate the diagnostic value of this method. METHODS: Between 2011 and 2013, a prospective study was conducted in Cameroon. Dry swabs from ulcerative lesions and fine-needle aspirates of nonulcerative lesions were examined for Ziehl-Neelsen (ZN) staining, followed by PCR targeting IS2404 and culture. Two 4-mm punch biopsies were performed in the center and in the periphery of each lesion. RESULTS: The 364 patients included in the study had 422 lesions (381 were ulcerative and 357 lesions were biopsied). Among the 99 ulcerated lesions with a final diagnosis of BU, histological features for BU were fulfilled in 32 lesions. 32/32 showed subcutaneous necrosis with a neutrophilic inflammatory infiltrate. 26/32 presented alcohol-resistant bacilli confirmed by ZN stain on histology. CONCLUSION: Punch biopsies help in establishing the correct diagnosis of BU and also in the differential diagnosis of chronic ulcers. The main histological feature for BU is diffuse coagulative necrosis of subcutaneous tissue, with acid-fast bacilli detected by ZN stain.