The skin biopsy specimen showed an extremely dense and extensive inflammatory infiltrate occupying all of the dermis except for the papillary dermis, which was grossly edematous. The overlying epidermis contained a scattering of lymphocytes and foci of spongiosis with cell degeneration. The dermal infiltrate consisted of a dense mass of neutrophils, most of which appeared to have a normal morphological appearance. Hemorrhage and edema were also present, and in the relatively spared areas, small blood vessels showed very marked endothelial swelling. A definite leukemic infiltrate was not identified. The microscopic features were in keeping with a primary neutrophilic dermatosis, such as PG or Sweet syndrome. The features seemed most consistent with PG.
Blistering Eruption on an Elderly Woman's Leg—Diagnosis. Arch Dermatol. 2004;140(4):479-484. doi:10.1001/archderm.140.4.479-h