Hansen’s Disease (Leprosy) – Clinical features (For professionals)

• Leprosy primarily affects the skin and nerves of humans. The lesions may be remarkably asymptomatic even after years of existence. However, some patients develop reactions resulting in painful cutaneous lesions accompanied by fever, malaise and other symptoms. Most frequently the first signs develop on the skin, even though the nerve is always involved simultaneously. In 5% of cases, the nerve may be the first manifestation evidenced by numbness, tingling pain, and muscle weakness and wasting of the extremities.
• Skin involvement presents as a broad spectrum of asymptomatic clinical lesions. It may be of any nature but most commonly: a macule, plaque or nodule. The duration of disease may be months to years. The pathognomonic feature is the loss of sensation to pin-prick over the lesion, but it must be emphasized that intact pin-prick sensation does not exclude leprosy.
• Motor function loss resulting in weakness of hands, feet and face may be gradual and painless. The affected nerve may be thickened, irregular or tender. Sensory nerve dysfunction may not be clinically obvious until testing of sensation is done. It may also present as wounds or blisters from heat and friction on the extremities unnoticed by the patient callosity of feet and dry skin. The ulnar, median, radial, lateral popliteal, posterior tibial and facial nerves are especially predisposed. The second pattern is the enlargement and tenderness of nerves around a skin lesion and the third is the glove and stocking anaesthesia in lepromatous leprosy.

Reactions in leprosy

• During the chronic course of the disease, leprosy may undergo a sudden inflammatory phase of exacerbation, called ‘Reactions’.
• Type 1 or Lepra reaction occur in Borderline leprosy following an increase or decrease in cell-mediated immunity.
• Type 2 or Erythema Nodosum Leprosum (ENL) occurs in lepromatous leprosy due to immune-complex reactions.
• Reactions may occur spontaneously, or may be precipitated by intercurrent infection, anaemia, stress, puberty, pregnancy, childbirth, or may be ushered in by immunological changes following effective treatment.

• In Type 1 reaction, some or all of the existing skin lesions show signs of acute inflammation (pain, tenderness and edema). Necrosis and ulceration can occur and the lesion subsides with desquamation. There may be rapid swelling and tenderness of nerves, and swelling of extremities and face may occur. Claw-hand, foot-drop and facial palsy may occur suddenly and paralysis may be permanent if the reaction is not treated quickly and adequately. Systemic symptoms like fever are uncommon.
• In Type 2 (ENL) reaction, existing leprosy lesions do not show clinical aggravation. Instead, sudden onset of crops of red tender nodules that last for a few days occur on normal unaffected skin. The lesion may become vesicular, pustular and gangrenous. Associated fever, malaise and toxic symptoms are common.

Adapted from Dr Seow Chew Swee: Update on Leprosy