S11C6P1-3 (lepromatous leprosy): The infiltrative lesions of lepromatous leprosy distort the margin of the ear.

S11C6P1-4 (lepromatous leprosy): the distortion of facial features is leontine.

S11C6P1-5 (leprosy): This infiltrate is perivascular. Some of the histiocytes are plump; they are individually isolated among the lymphocytes and plasma cells. Focally, small, irregular clusters provide an epithelioid quality. The combinations are borderline in character. Plasma cells provide a marker for a humoral contribution to the immune response. Blue arrows identify a small peripheral nerve. There is hyperplasia of Schwann cells ; a few lymphoid cells have infiltrated the nerve.

S11C6P1-6: In established lesions, the immune response to the lepra bacillus basically is expressed in variations of a histiocytic infiltrate. The variations include loose infiltrates of rounded, often vacuolated cells at one pole and compact infiltrates of acidophilic, epithelioid histiocytes at the other. The distinctions are difficult to put in words;  in one, or the other arrangement, the polar opposites are characterized as lepromatous or tuberculoid, respectively. In this illustration, the histiocytes are loosely arranged and rounded. The patterns are not fully lepromatous, but are not clearly tuberculoid (epithelioid); they are borderline, but on the lepromatous side of a spectrum. A loose infiltrate of lymphocytes, among activated histiocytes, is compatible with a lesion that is not polar in its characteristics. The infiltrates are mostly perivascular.

S11C6P1-7 (leprosy): Lymphoid cells, and plasma cells infiltrate the perineurium of this small peripheral nerve (green arrows). Lymphoid cells and vacuolated cells are present in the endoneurium among the fascicles of Schwann cells. The vacuolated cells are lepra cells and would be expected to contain phagocytyzed organisms.