Lupus vulgaris
* A common form of cutaneous tuberculosis although the cut. Tb is rare.
* The skin is involved by endogenous spread from an old reactivated Tb focus in the lungs or through lymphatics from a Tb cervical lymph node.
* Rarely LV is due to exogenous reinfection.
* LV is a form of postprimary Tb that occurs in a sensitized person.
* Any age can be involved by LV and it is more common in females.
* > 80% of the cases affect the head and neck region especially the nose, ears and the scalp. The trunk and extremities are involved in < 20% of the cases.
* Asymptomatic, well-defined, reddish brown, irregular plaques with characteristically soft consistency having a smooth or slightly scaly surface with deep-seated nodules. Usually there is only one or few lesions.
* Diascopy reveals an apple-jelly colored (yellowish-brown) infiltrative nodules which is a characteristic of LV.
* The lesions tend to extend peripherally and heal with atrophic “unhealthy” scarring at the center. However, new brownish infiltrates or nodules may appear within the atrophic areas which is another characteristic feature of LV.
Variants of LV:
1. Hypertrophic LV: Soft tumorous nodules.
2. Hyperkeratotic (Warty) LV: Verrocous surface.
3. Ulcerative LV: Punched-out superficial ulcers surrounded by soft brownish infiltrates.
4. Mutilating LV: involvement of underlying cartilages (but not bones) resulting in mutilation especially of the nose and ears with prominent scarring.
* The course of LV: a slow, progressive, prolonged course which may be life-long if left untreated. Rarely, SCC may complicate LV.
Differential diagnosis:
1. DLE
2. Chronic lupoid leishmaniasis
3. Lepromatous leprosy
4. Tertiary syphilis
5. SCC