S12C14aP4aGranuloma



S12C14aP4a-1: In this area of subcutaneous fat, there is a central zone of fibrinoid necrosis. At the periphery of the zone of necrosis, epithelioid histiocytes are arranged in granulomatous patterns. Two of the granulomas have the qualities of lipogranulomas (a non-specific reaction of fat to injury) (Mycobacterium chelonii infection).

S12C14P4-2: Mycobacteria chelonii infection (acid fast stain).


S12C14P4-3: Blue arrows outline the superior border of a palisaded granuloma in the upper 1/3 of the reticular dermis. Histiocytes are arranged in palisades and traceries at the periphery of an area of altered dermal connective tissue. With this H&E stain, the collagen bundles are small in diameter and are loosely spaced (actinic granuloma - granulomatous elastolysis of actinically damaged skin). The zone of altered connective tissue is above the interface defined by the row of blue arrows (actinic granuloma).

S12C14P4-4: A zone of altered connective tissue extends to the margin of the field on the left; this is the trail. Histiocytes form loose palisades at the margin of the zone of altered connective tissue. There are perivascular infiltrates of lymphoid cells (actinic granuloma).

S12C14P4-5: Near the top of the field, the interface between the papillary dermis and the reticular dermis is defined by the coarse elastic fibers of the reticular dermis. Near the center of the field, the pattern of elastic fibers of the reticular dermis is interrupted by a zone of granulomatous, interstitial inflammation and elastolysis. There are numerous giant cells (granulomatous elastolysis of actinic granuloma) (orcein stain).

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