Histopathologic features of Mycobacterium ulcerans infection

Abstract

Because of the emergence of Buruli ulcer disease, the World Health Organization launched a Global Buruli Ulcer Initiative in 1998. This indolent skin infection is caused by Mycobacterium ulcerans. During a study of risk factors for the disease in Ghana, adequate excisional skin-biopsy specimens were obtained from 124 clinically suspicious lesions. Buruli ulcer disease was diagnosed in 78 lesions since acid-fast bacilli (AFB) were found by histopathologic examination. Lesions with other diagnoses included filariasis (3 cases), zygomycosis (2 cases), ulcerative squamous cell carcinomas (2 cases), keratin cyst (1 case), and lymph node (1 case). Thirty-seven specimens that did not show AFB were considered suspected Buruli ulcer disease cases. Necrosis of subcutaneous tissues and dermal collagen were found more frequently in AFB-positive specimens compared with specimens from suspected case-patients (p<0.001). Defining histologic criteria for a diagnosis of Buruli ulcer disease is of clinical and public health importance since it would allow earlier treatment, leading to less deforming sequelae.

Figure 1

a, Hematoxylin and eosin stain of a lesion specimen showing definitive Buruli ulcer disease in the preulcerative stage (original magnification 50x). Notice the psoriasiform epidermal hyperplasia (H), superficial dermal lichenoid inflammatory infiltrate (I), and necrosis of subcutaneous tissues (N). b, Ziehl-Neelsen stain of the same nodule, showing abundant colonies of acid-fast bacilli in the necrotic subcutaneous tissues (original magnification 100x).

Figure 2

a, hematoxylin and eosin stain of the pseudoepitheliomatous hyperplasia of the epidermis in a lesion specimen showing definitive Buruli ulcer disease in the ulcerative stage (original magnification 100x). b, hematoxylin and eosin stain of the necrotic collagen (c) accompanied by mild inflammatory infiltrate in the dermis of a definitive Buruli ulcer disease lesion in the ulcerative stage (original magnification 400x). n, neutrophis; m, mononuclear cells.