S3C23P11-Lichens-misc

S3C23P11-1: Lichen planus of the periungual and subungual areas.

S3C23P11-2: An attempt to biopsy an ungual lesion of lichen planus produced this specimen. This hyperplastic superficial unit of the epidermis shows the characteristic features of lichen planus. In addition, at the base of the specimen near the center of the field, there is is an erosive defect with infiltrates of lymphocytes and histiocytes.

S3C23P11-3: Lesions of lichen nitidus.

S3C23P11-4: The focality of the process is a distinguishing feature of the lichenoid reaction which characterizes lichen nitidus. Not all examples are as classic in pattern as is this one. The loose spacing of nuclei in the dermal component is a reflection of the high component of histiocytes in the infiltrates (histiocytes have more cytoplasm than lymphocytes; in a histiocyte-rich infiltrate, the nuclei tend to be loosely spaced). Occasional multinucleated, histiocytic giant cells are common in lichen nitidus. The infiltrates press upon, and have eroded, the basal unit of the epidermis.

S3C23P11-5: At higher magnification, the high component of histiocytes contributes a granulomatous character to the infiltrates. The green arrow identifies a histiocytic giant cell. The erosive defect in the basal unit of the epidermis is identified with blue arrows. Over the micronodule, a thin superficial unit of the epidermis survives. For this example, the changes in the epidermis and at the dermal-epidermal interface are lichen planus-like .

S3C23P11-6: The section had faded, but histiocytes are a prominent feature. A blue arrow identifies a giant cell. The red arrows point to a cluster of histiocytes in epithelioid patterns (lichen nitidus).

S3C23P11-7: For some examples of lichen nitidus, the overall patterns, but for their focal nature, display all the features of a lichen planus-like reaction. Like other lichenoid reactions, lesions of lichen nitidus have a life history.

 

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