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How do tuberculoid leprosy and lepromatous leprosy differ?

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Sign reading Gandhiji Prem Nivas Leprosy Centre Titagarh conducted by Missionaries of Charity, with a crucifix above the sign on a decorated building facade. — leprosy The Gandhiji Prem Nivas is a center for people with leprosy that was established by Mother Teresa in 1958 and is run by the Missionaries of Charity in Titagarh, India.

Tuberculoid and lepromatous leprosy differ primarily in the body's immune response to the bacterium Mycobacterium leprae.12

Tuberculoid Leprosy

This form occurs in individuals whose tissues exhibit an intense cellular immune response. Immune cells crowd the area to seal off the bacilli, resulting in very few organisms being present. While this response successfully prevents the bacteria from multiplying and spreading throughout the body, it causes significant damage to local tissues, including sweat glands, hair follicles, and nerves. This leads to firm, dry skin patches, loss of sensation, and potential paralysis or deformity.1

Lepromatous Leprosy

In contrast, lepromatous leprosy is characterized by a weak cellular response, allowing the bacilli to multiply freely and spread widely through the skin's lymphatic channels. The bacteria are found in enormous numbers, often causing thickening and corrugation of the skin, particularly on the face, which can result in a leonine appearance. Unlike the tuberculoid form, the disease does not adhere strictly to nerves, though it can cause soft nodules and destructive sores on the ears, nose, and cheeks.1