The histopathology of type I (lepra) and type II (ENL) reactions in leprosy

The histopathological features in type I (lepra) reaction comprised a loose and disorganised granuloma in the upper and mid-dermis, dermal edema and variable cellular contents, namely, epithelioid cells, lymphocytes, giant cells, and macrophages. While ENL reactions, were characterised by predominant involvement of subcutaneous vessels, vasculitis, and polymorphonuclear infiltration in and around the blood vessels.