Ch 23 D-E Junction &
Membranous Loops

F1Ch23 (104578): The epidermis shows hyperplasia of the superficial unit with a thin, poorly developed basal unit. There is an increased number of cells in the basal layer with the characteristics of melanocytes (melanocytic hyperplasia).There are dyskeratotic cells in the epidermis. The poorly developed basal unit shows intercellular edema. Some of the basal cells show basal hypereosinophilia of their cytoplasm. There is a wide, pale zone at the level of the basement membrane (blue arrows).


f2Ch23 (104578): A basal unit is not well-defined. The basal unit shows an increased number of clear cells (keratinocytes?). There are scattered dyskeratotic cells. Some of the basal cells have prominent nucleoli. The basement membrane is ill-defined. There are scattered melanophages near the dermal-epidermal interface. The upper portion of the dermis is hypercellular; some of the cells are dendritic in outline. The basic pattern at the dermal-epidermal junction is that of a variant of a cell-poor lichenoid reaction.

Buster (the plight of feral cats)


F3Ch23 (104578): A thin basal unit is represented. Coarse basement membrane material is irregular in distribution. There are patterns of reduplication of basement membrane in areas. To the right of the center of the field, there is a small sub-epidermal defect. At the extreme right, the basement membrane is thin and there are vacuolar changes. In this same area, there is a basement membrane loop (green arrows) containing two cells; the smaller cell is spindle-shaped; the plumper cell is triangular in outline and has a larger nucleus. The fibrous mat is abnormal; there is a complex pattern of fibers in the background with scattered, wavy, acidophilic, coarser bundles. There is no evidence of a normal papillary dermis.


F4Ch23 (104578): There is a thin basal unit. A red arrow identifies a dyskeratotic basal cell. Green arrows identify cells with a lateral zone of acidophilia; this might be an extension of basement membrane material but seems to be evidence of early keratinization of the cytoplasm of basal cells. The coarse, acidophilic basement membrane has a fuzzy outline. There are vacuolar changes, particularly on the epidermal side of the basement membrane. A yellow arrow identifies a partially defined basement membrane loop containing two distinctive cells. Blue arrows identify other patterns of “looping.” The pattern of the adjacent fibrous tissue is abnormal.


F5Ch23 (104578): The basal unit of the epidermis is thin; some of the basal cells show dyskeratosis. The basement membrane is coarse, fuzzy, and acidophilic. Basement membrane material is duplicated; there are scattered “loops,” two of which appear to be within the dermis and not attached to the basement membrane. There are vacuolar changes on the dermal side of the basement membrane. The nuclear characteristics of the cells identified by the yellow arrows would indicate that the cells are histiocytes. Might the basement membrane changes be a hindrance to the migration of histiocytes into the epidermis.


F6Ch23 (104578): In areas, the basement membrane appears to be segmented. A green arrow identifies a poorly loop containing a mononuclear cell. Red arrows identify incomplete loops (reduplicated basement membrane material) that outline irregular spaces. In one of these spaces, two cells, each with different cytologic features, in a close embrace. One cell could be a histiocyte, and the other has a dendritic process. The matrix is abnormal and most of the fibers appear to represent duplicated basement membrane material.


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