Fibrinoid change at the dermoepidermal junction occurs in this condition and also in skin that has been externally traumatized as in an excoriation. This fibrinoid change is so characteristic that a diagnosis of 'chondrodermatitis nodularis versus excoriation' can be given based upon a superficial biopsy of an ear with no other clinical history. If there is an erosion or ulcer, the fibrinoid change is seen at the edge of the defect. Fibrinoid change may be relatively superficial, or it may extend in a column as far down as to the cartilage.

The epidermis may be intact or eroded. The adjacent epidermis is often acanthotic and may even be pseudoepitheliomatous.  Increased vascularity is common. Inflammatory infiltrates are variable or may be absent. So-called changes in the cartilage have been overemphasized in the literature. It is quite likely that the apex of  the ridge of cartilage acts as a pointed anvil resulting in the cutaneous changes above it. It is not surprising that the lesion may recur if some of the underlying cartilage is not removed.
 

	Scan power showing the cartilage of the helix (ctlg) plus acanthotic epidermis on each side of the sore area. Note the vertical change in the skin above the apex of the cartilage.
	Low power view of the sore area. The epidermis is attenuated, and there is increased vascularity peripheral to the vertical zone of altered dermis.
	High power view of above. Fibrinoid change is prominent at the dermoepidermal junction, and it extends into the papillary dermis. Fibroplasia is also present.

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