Photomicrographs of a punch biopsy from a<unk>  plaque lesion. In the left image, the tissue sample has been stained with hematoxylin and eosin, a common stain for histopathology examination. In the right image, it has been stained with Ziehl–Neelsen stain, which helps to visualize mycobacteria. The inset shows red-staining (acid-fast) bacilli, suggestive of mycobacteria. As<unk>  most commonly occurs in low-resource settings, treatment is often initiated by a clinician based on signs and symptoms alone. Where available, diagnosis may then be confirmed by polymerase chain reaction (PCR) to detect M.<unk> ans DNA or microscopy to detect mycobacteria. The gold standard test is real-time PCR to detect a DNA sequence termed IS2404 that is unique to M.<unk> ans. This method detects M.<unk> ans in 54–84% of infected people, and is highly specific to M.<unk> ans. In wealthier healthcare settings, diagnosis is routinely based on PCR results. In low-resource settings, PCR is often unavailable, or can only be performed later at a centralized diagnostic laboratory. For microscopy, fluid is typically taken from the<unk> 's edge by fine-needle aspiration or by swabbing the edge of the<unk> . The fluid is then stained with the Ziehl–Neelsen stain which makes mycobacteria visible. In practice microscopy detects M.<unk> ans in just 30–40% of infected people, making it a relatively insensitive diagnostic test. For many bacterial infections, the gold standard for diagnosis is isolating and growing the infective organism in laboratory media. M.<unk> ans can be grown in laboratory media,<unk> t its extremely slow growth rate prevents this from being used diagnostically; even under optimal growth conditions, the bacteria must grow for 9 to 12 weeks before they can be easily detected and identified. Another method of diagnosis is to take a tissue sample from the<unk>  and examine it under histological stains. This requires more invasive sampling and review by a trained pathologist, and is rarely used in places where<unk>  is endemic. Other<unk> ative diseases can appear similar to<unk>  at its various stages. The nodule that appears early in the disease can resemble a<unk> g bite, sebaceous cyst, lipoma, onchocerciasis, other mycobacterial skin infections, or an enlarged lymph node. Skin<unk> s can resemble those caused by leishmaniasis, yaws, squamous cell carcinoma, Haemophilus ducreyi infection, and tissue death due to poor circulation. More diffuse lesions can resemble cellulitis and fungal infections of the skin.
Buruli ulcer
Lichen planus
Callous ulcer
Lichen sclerosus
Kangri ulcer
Lipschütz ulcer
Stercoral ulcer
Melanosis coli