Testing for loss of sensation with monofilament In countries where people are frequently infected, a person is considered to have<unk>  if they have one of the following two signs: * Skin lesion consistent with<unk>  and with definite sensory loss. * Positive skin smears. Skin lesions can be single or many, and usually hypopigmented, although occasionally reddish or copper-colored. The lesions may be flat (macules), raised (papules), or solid elevated areas (nodular). Experiencing sensory loss at the skin lesion is a feature that can help determine if the lesion is caused by<unk>  or by another disorder such as tinea versicolor. Thickened nerves are associated with<unk>  and can be accompanied by loss of sensation or muscle weakness, but muscle weakness without the characteristic skin lesion and sensory loss is not considered a reliable sign of<unk> . In some cases, acid-fast<unk>  bacilli in skin smears are considered diagnostic; however, the diagnosis is typically made without laboratory tests, based on symptoms. If a person has a new<unk>  diagnosis and already has a visible disability caused by<unk> , the diagnosis is considered late. In countries or areas where<unk>  is uncommon, such as the United States, diagnosis of<unk>  is often delayed because healthcare providers are unaware of<unk>  and its symptoms. Early diagnosis and treatment prevent nerve involvement, the hallmark of<unk> , and the disability it causes. There is no recommended test to diagnose latent<unk>  in people without symptoms. Few people with latent<unk>  test positive for anti PGL-1. The presence of M. leprae bacterial DNA can be identified using a polymerase chain reaction (PCR)-based technique. This molecular test alone is not sufficient to diagnose a person, but this approach may be used to identify someone who is at high risk of developing or transmitting<unk>  such as those with few lesions or an atypical clinical presentation. Classification Several different approaches for classifying<unk>  exist. There are similarities between the classification approaches. * The World Health Organization system distinguishes "paucibacillary" and "multibacillary" based upon the proliferation of bacteria. ("pauci-" refers to a low quantity.) * The Ridley-Jopling scale provides five gradations. * The ICD-10, though developed by the WHO, uses Ridley-Jopling and not the WHO system. It also adds an indeterminate ("I") entry. * In MeSH, three groupings are used. WHO Ridley-Jopling ICD-10 MeSH Description Lepromin test Paucibacillary tuberculoid ("TT"),borderlinetuberculoid ("BT") A30.1, A30.2 Tuberculoid It is characterized by one or more hypopigmented skin macules and patches where skin sensations are lost because of damaged peripheral nerves that have been attacked by the human host's immune cells. TT is characterized by the formation of epithelioid cell granulomas with a large number of epithelioid cells. In this form of<unk>  Mycobacterium leprae are either absent from the lesion or occur in very small numbers. This type of<unk>  is most benign. Positive Multibacillary midborderlineorborderline ("BB") A30.3 Borderline Borderline<unk>  is of intermediate severity and is the most common form. Skin lesions resemble tuberculoid<unk> , but are more numerous and irregular; large patches may affect a whole limb, and peripheral nerve involvement with weakness and loss of sensation is common. This type is unstable and may become more like lepromatous<unk>  or may undergo a reversal reaction, becoming more like the tuberculoid form. Multibacillary borderline lepromatous ("BL"),and lepromatous ("LL") A30.4, A30.5 Lepromatous It is associated with symmetric skin lesions, nodules, plaques, thickened dermis, and frequent involvement of the nasal mucosa resulting in nasal congestion and nose bleeds, but, typically, detectable nerve damage is late. Loss of eyebrows and lashes can be seen in advanced disease. LL is characterized by the absence of epithelioid cells in the lesions. In this form of<unk> , Mycobacteria leprae are found in lesions in large numbers. This is the most unfavorable clinical variant of<unk> , which occurs with a generalized lesion of the skin, mucous membranes, eyes, peripheral nerves, lymph nodes, and internal organs. Negative<unk>  may also occur with only neural involvement, without skin lesions.
Leprosy
Sporotrichosis
Onychomycosis
Mumps
Tinea barbae
Tinea faciei
Trichinosis
Tinea manuum