Lupus vulgaris is a skin condition caused by Mycobacterium tuberculosis, presenting as small nodules that can lead to tissue destruction. It is treatable with a combination of antibiotics and can affect any part of the body. Diagnosis is confirmed through a skin biopsy.
Lupus vulgaris is a painful lumpy skin condition most commonly caused by the microorganism Mycobacterium tuberculosis. It usually affects the face or buttocks and trunk. The term “lupus” is used to refer to the skin ulceration and necrosis that occurs when left untreated. Lupus vulgaris is also known as tuberculosis lupus cutis or tuberculosis cutis lupus due to its causative agent. Like any other form of tuberculosis, it is treatable with the four-drug combination of isoniazid, rifampicin, ethambutol, and pyrazinamide.
Mycobacterium tuberculosis preferably remains and thrives in lung tissue, causing pulmonary tuberculosis (TB). When tuberculosis occurs in other organs and tissues, it is referred to as extrapulmonary tuberculosis. There are several forms of extrapulmonary tuberculosis, including miliary tuberculosis, scrofula, verrucous cutaneous tuberculosis, tuberculosis, metastatic tuberculous abscesses, and metastatic tuberculous ulcer or tuberculous gum. These, along with lupus vulgaris, can present as skin conditions caused by tuberculosis infection.
Relatively rare, lupus vulgaris is a variant of persistent and progressive cutaneous tuberculosis. The initial lesions are small, sharply defined nodules that are reddish-brown in color and gel-like in consistency. These lesions are also known as apple jelly nodules. Persistence of these lesions leads to coalescence and tissue destruction. There is no age range free from lupus vulgaris, but most patients go to the doctor before the age of 30 with these symptoms.
Among Caucasians, the head and neck region is typically affected. In Asians, lupus vulgaris most commonly occurs on the buttocks and extremities. A few cases of penile involvement have also been reported.
The causative organism reaches the skin through various routes. One route is direct inoculation, in which the organism spreads to the dermis after entering an open skin wound. The hematogenous, or blood, route and the lymphatic route may be used when the organism is transferred to the skin from an affected internal organ. Another route is direct extension, from infected joints or subcutaneous glands.
The diagnosis of lupus vulgaris is confirmed through a skin biopsy of the affected area. Histopathologic findings would indicate the presence of case-forming epithelioid granulomas that contain acid-fast bacilli. To rule out coexisting pulmonary tuberculosis infection, a sputum culture or chest x-ray may be ordered. A Mantoux tuberculin skin test and other X-ray tests may also be done.
The most effective treatment of lupus vulgaris is oral anti-tuberculosis drugs. Other antibiotics may also be given to treat any secondary bacterial infections. Treatment with these drugs lasts for months or years, depending on the severity of the disease. When the face is severely disfigured or large areas of skin are necrotic, surgical excision of the affected areas may be recommended.
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