Lupus vulgaris is a chronic skin condition caused by infection with Mycobacterium tuberculosis. This form of tuberculosis primarily affects the skin, distinguishing it from other forms that impact internal organs. It is important to note that lupus vulgaris is entirely different from Systemic Lupus Erythematosus (SLE), an autoimmune disease where the immune system mistakenly attacks its own tissues. The shared “lupus” in their names can cause confusion, but their origins and mechanisms are distinct.
Understanding Lupus Vulgaris
Lupus vulgaris arises from infection with Mycobacterium tuberculosis, the same bacterium responsible for pulmonary tuberculosis. The infection typically reaches the skin through direct inoculation, where bacteria enter through a break in the skin, or more commonly, from an existing tuberculosis infection elsewhere in the body, such as the lungs. It can also develop at the site of a BCG vaccination. Bacteria may remain inactive for years before leading to characteristic skin lesions.
The condition manifests as painful reddish-brown nodules that slowly expand to form irregularly shaped red plaques. These lesions can also appear as raised or ulcerated areas on the skin. A distinctive feature, observed during diascopical examination, is an “apple-jelly” appearance. These skin lesions may become crusted over time.
Lupus vulgaris commonly affects the face, particularly around the nose, eyelids, lips, cheeks, and ears, as well as the neck and extremities. Lesions may be single or multiple. If left untreated, these lesions can develop into disfiguring skin ulcers, causing significant scarring and disfigurement.
Diagnosis and Treatment Approaches
Diagnosis involves a combination of clinical examination and specific laboratory tests. A skin biopsy is often performed, taking a small tissue sample from the affected area. Histopathological examination of this sample typically reveals well-formed granulomas, which are collections of immune cells, sometimes with necrotic centers.
Microbiological tests on the biopsy sample confirm the presence of Mycobacterium tuberculosis. These include culturing the bacteria, which can take several weeks, and Polymerase Chain Reaction (PCR) for faster detection of bacterial DNA. Other diagnostic methods include a tuberculin skin test (Mendel-Mantoux test) and a Quantiferon test, which indicate tuberculosis exposure. Imaging studies like chest X-rays or CT scans may be conducted to check for underlying pulmonary tuberculosis.
Treatment for lupus vulgaris involves long-term multi-drug anti-tuberculosis therapy (ATT), similar to the regimen used for pulmonary tuberculosis. An initial phase of treatment lasts eight weeks, utilizing a combination of drugs such as rifampicin, isoniazid, pyrazinamide, and ethambutol. This phase aims to eliminate the majority of bacteria.
Following the initial phase, a consolidation phase continues for several months to eradicate any remaining bacteria. The total duration of antitubercular therapy for lupus vulgaris can range from 6 to 24 months, with treatment continuing for at least two months after the skin lesions have cleared. Strict adherence to the complete treatment course is important to ensure full eradication and prevent recurrence or drug resistance.
Managing the Condition and Outlook
After completing treatment for lupus vulgaris, ongoing monitoring is important to confirm the infection’s eradication. Regular follow-up appointments allow healthcare providers to observe for recurrence and address potential long-term effects. Improvement is typically observed within approximately one and a half months of starting therapy.
If left untreated, lupus vulgaris can lead to significant long-term effects, including severe scarring and disfigurement. In rare instances, chronic, untreated lesions have the potential for malignant transformation into skin cancers. Timely and effective intervention is important.
With proper and timely diagnosis and adherence to the prescribed multi-drug anti-tuberculosis therapy, the prognosis for lupus vulgaris is generally favorable. Most patients achieve a complete cure, with the infection fully cleared from the body. Early diagnosis and consistent adherence to the full course of treatment are important for a positive outcome and minimizing long-term complications.