Clinical Characteristics

The clinical features of leprosy reflect the pathology, which is in turn dependent upon the balance between bacillary multiplication and the host's cell-mediated immune response.
The initial lesion, "indeterminate leprosy", is a symptomless, ill-defined, slightly hypopigmented macule, commonly on the face or trunk. There are no other changes, no loss of sensation, no loss of sweating or hair. Diagnosis may depend on careful continuing observation and the lesion may be ignored by both the patient and the doctor. It usually heals spontaneously. After the indeterminate lesion, leprosy may develop in two quite different ways:

1. Lepromatous leprosy, which is the "open" or infectious type in which skin nodules and respiratory mucosa are laden with bacilli. These patients present clinically because of the deformity and swelling of the skin and destruction of the cartilages of the face (Fig. 34.3).

2. Tuberculoid leprosy, which is usually noninfectious and in which there will be a few bacilli in the skin or nerves. Patients with this type of leprosy complain of anesthesia or of nerve tenderness, particularly where the nerves are superficial, e.g., passing over a bony surface, lying near a joint, or exposed to variations in temperature as in the limbs. There may be pain in the nerve itself, but also painful paresthesia and hyperesthesia in the nerve distribution.

As mentioned above, these are the two main (the "polar") types of leprosy. Between these polar forms there are a number of subgroups, the "borderline", "intermediate" or "dimorphous" forms, in which one or another variety predominates: for example it is possible for purely neural leprosy to occur without depigmented skin lesions, but it is uncommon. Any of the borderline lesions may change polarity and recurrent lepra reactions tend to shift the disease in one direction or another.

Lepromatous Leprosy

The skin lesions are asymmetrical and diffuse over the entire body. There will be erythema and diffuse infiltration, resulting in plaque-like thickening, especially in the lobes of the ears and the face. This causes the characteristic "leonine" appearance (Fig. 34.3 C). These nodules may ulcerate and discharge copious bacilli. The nerves are not affected in the early stages, but almost invariably become so later. There may be gradual loss of eyebrows (madarosis), and gynecomastia occurs because of raised estrogen and testicular atrophy (Fig. 34.4). As the disease progresses the nasal cartilages are destroyed, causing nasal deformity. The eyes are damaged by lepromas and keratitis.

In Mexico, Central and South America, in the lucio variant of lepromatous leprosy there is a severe immune complex-mediated vasculitis from heavy bacterial colonization of vascular endothelium. The result is deep dermal infarction and ulceration, making the patients at risk for opportunistic infections (Fig. 34.3 F). Superficially the appearance has been mistaken for anthrax. Another serious complication of lepromatous leprosy may be hyperinfection with strongyloidiasis: this may be fatal.

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Fig. 34.4A-D. Lepromatous leprosy. A Madarosis (loss of eyebrows), nodular infiltration around the elbows, and facial thickening. B Another African patient with multiple facial nodules and marked skin thickening. The ear lobe is infiltrated. The linear marks on the face are due to traditional tribal scarification. C An African patient with more advanced leprosy. His fingers have been lost, his face has the typical leonine appearance, and he has developed gynecomastia. D Marked lepromatous gynecomastia in another .