Leprosy

Key Points
Chronic skin condition, also known as Hansen’s disease
Caused by chronic bacterial infection
Several clinical forms of the disease exist
Often consists initially of a numb feeling in the affected area, followed by skin lesions

Hansen disease, or Leprosy, is a chronic skin condition caused by a chronic bacterial infection which can affect the skin and mucous membranes. It initially presents, after a potentially years-long incubation period, as a numb feeling in the affected area. This will be followed, sometimes by a number of years, by skin lesions (each clinical form presents differing lesions), and continued loss of sensory perception. Sensory perception loss typically begins in the toes or fingertips, and will lose the sense of temperature, followed by light pressure, pain, and finally, deep pressure.

There are six clinical forms of Leprosy, differentiated by formation of lesions, severity, and by associated symptoms. These are indeterminate, tuberculoid, borderline tuberculoid, borderline borderline, borderline lepromatous, and lepromatous Leprosy. The condition typically begins with indeterminate Leprosy, the disease in its earliest stage. This can be cured if treated at this stage or if untreated progression into another form of the condition will occur. In all forms of the condition, except lepromatous, an affected person may see shifts in the severity of the disease, going from one stage, worsening, then improving.

Tuberculoid lesions consist of a large, asymmetrical pale spot, or a large, well-defined red patch, with a loss of sensation in the affected area in some persons. This may be accompanied by the thickening of nerves in the affected area, which will also be tender, and leads to loss of function.

Borderline tuberculoid lesions are similar to tuberculoid lesions, except there are multiple, smaller lesions. Borderline borderline lesions are typically multiple red, irregular plaques, accompanied by only moderate loss of sensation. Borderline lepromatous lesions take many forms, from plaques to papules, though lesions which resemble inverted saucers are typical. This is not accompanied by sensory loss.

Lepromatous lesions also take on many forms, and while early affects on the nervous system may not be noticed, other early symptoms include nasal congestion, bleeding and discharge, and swelling in the legs and ankles. If left untreated, lepromatous Leprosy can lead to a host of issues, including severe facial and extremity deformity, involvement of the eyes which can lead to blindness, thickened, ulcerating skin on the legs, sterility, breast enlargement in men, organ involvement, and generalized sensory loss.

Hansen’s disease is caused by the bacteria Mycobacterium leprae. The bacteria are more common in warm, wet climates, and as such persons in these areas are at increased risk for contracting the infection. Armadillos are known to be a reservoir for the bacteria.

Differential Diagnosis (Other conditions with similar appearance)Onchocerciasis
Trachoma
Uveitis, Anterior, Granulomatous

Diagnosis
Key Points
Initial diagnosis based on characteristic appearance of the affected area
Skin biopsy or other tests will be performed to confirm diagnosis and rule out other conditions

Hansen disease is initially diagnosed based on the characteristic appearance of clinical symptoms in the affected area, but skin biopsy or other testing is necessary to confirm diagnosis and to rule out other conditions.

Treatment
Goal of treatment is to control infection and limiting physical deformity
Combinations of various therapies, including antibiotics and corticosteroids, are used depending on type and severity of the condition

In the treatment of Hansen disease, controlling the bacterial infection is of paramount importance. Secondly, ensuring that potential deformity is prevented is key in treatment. antiobiotics (dapsone, rifampicin, clofazimine, minocycline, ofloxacin, clarithromycin) are typically used, singly or in combination with other antibiotic medications, to control and eliminate infection. Oral corticosteroids can assist in preventing damage to the nervous system by reducing the swelling associated with the condition, as can thalidomide. Courses of both types of medications will be long, sometimes years, and must be completed in full.