This 20 year-old female grew up in the Marshall Islands. She presented with a red, scaly plaque on her knee. She also reported decreased sensation. The clinican's differential diagnosis was leprosy, psoriasis, or erythema annulare centrifugum. While not so rare in other parts of the world, a good case of leprosy continues to spark excitement here. I should have the pleasure to see more examples as the 9-banded armadillo roams this region (Texas). This is an example of Hansen disease. The presence of numerous acid-fast-positive organisms favors a diagnosis of lepromatous leprosy. This case is probably best classified as borderline lepromatous since the granulomas are a little better formed and there is a sense of neurotropism, features seen in the tuberculous form...cool case.
The histiocytic infiltrate consists of loosely-formed granulomas. The histiocytes are mildly foamy. There is a mild lymphocytic component to the infiltrate. An apparent grenz zone separates the infiltrate from the overlying epidermis.