S12C12P2-2: A zone of acellular necrosis is to the right, and above. Histiocytes are clustered at the interface between viable and necrotic tissue. To the left of the zone of palisaded cells, epithelioid histiocytes are clustered in tubercle-like fashion. Green arrows point to one such aggregate of epithelioid histiocytes; this tubercle-like aggregate is partially surrounded by the hyperplastic epithelium (pseudo-epitheliomatous hyperplasia: transepidermal elimination-like pattern).

S12C12P2-4: In this lesion, epithelium has extended into a zone of granulomatous inflammation. Inflammatory cells have collected in a defect in the hyperplastic epithelium (atypical acid fast infection).

S12C12P2-5: The hyperplastic epithelium has extended into the zone of granulomatous inflammation.The cells of the infiltrating epithelium are pale and individually enlarged (i.e., keratoacanthoma-like qualities [i.e., qualities of a type which is commonly manifested in lesions showing pseudo-epitheliomatous hyperplasia]).

S12C12P2-6: Most of the inflammatory cells in the epithelial defect, to the left, are neutrophils. The infiltrates of the neighboring dermis are granulomatous; histiocytes are closely spaced in epithelioid patterns (pattern of suppurative granuloma). Connective tissue fibers perforate the infiltrating squamous epithelium. The cytoplasm of the keratinocytes of the squamous epithelium is pale (atypical acid fast infection).

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