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1. Histopathology of Inflammation

2. Minimal Deviation Melanoma, etc.

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F1Ch41 (Q8152): This lesion seems to satisfy criteria for a variant of a follicular hamartoma of the butterfly area of the face. It bulges at the surface, but is also inverted. There is hyperkeratosis, parakeratosis, and papillomatosis. At the base, epithelial components are confluent; the lesion is expansile. The columns of tumor cells are vertically oriented.

F2Ch41: At higher magnification, over large areas, the basal unit-like component is more extensively represented than the superficial unit-like component. The pallor in the area to the right is evidence of degeneration. Small whorls are irregularly spaced.

F3Ch41: There is a preponderance of small cells. These cells show nuclear hyperchromatism. To the left, at the top of the field, a superficial unit-like component shows cytoplasmic pallor; many of the cells of this area have perinuclear vacuoles. Melanophages are present in the stroma, near the basement membrane zone.

F4Ch41: The basal unit-like component is prominent. Its cells are small and dark. There is some degree of atypia in this component; nuclei show variation in size and outline, and chromatin is dense. The superficial unit-like component is also prominent; nuclear atypia is a feature. There are irregularly spaced whorls. About some of the whorls, some of the keratinocytes are vacuolated. There are pigmented dendritic cells near the interface between the basal unit-like component, and the superficial unit-like component. Small bulbous protrusions distort the  dermal-epidermal interface

F5Ch41: The patterns are not as clearly defined as in most of the other illustrative cases; the section was faded. Cytoplasmic pallor, and vacuolated cells are a feature of the component among the whorls, especially on the left. At the deep margin of the lesion, at about the junction between the left and right hand sides of the field, there is a change in cytologic features. This is marked on the right by a population of plump keratinocytes with more convincing features of a superficial unit-like component. All along the dermal-epidermal interface, a thin band of chronic inflammatory cells hug the epithelial component. The inflammatory cells have migrated into the basal layer to produce lysis and dyskeratosis of the respective epithelial cells; the pattern is that of a lichen planus-like reaction. There are numerous melanin deposits in the area of the lichenoid reaction. In part, the adjacent superficial unit-like component might also be included, as a component of the lichenoid reaction.

F6Ch41: A follicle-like ostium is represented; to the left and above the keratinized debris in the lumen of the follicle, there is no granular layer; in this area, the debris is parakeratotic. The zone of parakeratosis continues along the surface away from the lumen of the follicle. In the region of the lumen, the lichenoid reaction has destroyed the basal layer. On the opposite side of the lumen, two yellow arrows identify a distinctive interface; an interface like this is produced when one clone of cells abuts upon a different clone. This interface reaction is of the type that is emphasize in the diagnosis of lesions of porokeratosis; it also is the type that is commonly seen at the periphery of an actinic keratosis. In fact, there is mild to moderate atypia in the basal unit component below the lower of the two yellow arrows. In this area, a neoplastic clone abuts upon a more normal clone, with the latter contributed by the epithelium of the follicle.