Ch29P21-L3 Tricholemmal  
Basosquamous CA

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1. Histopathology of Inflammation

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F1Ch29 (continuation of Ch29a): The lesion is expansile.The lesion bulges to the right, and much of the epithelium in this area is acidophilic; the acidophilic epithelium qualifies as superficial  unit-like type. Focally, along the deep margin of the lesion, clusters and nests of epithelial cells have pale cytoplasm. In areas, columns of epithelial cells extend from the epidermis to become part of the tumor. Some of the columns are confluent. Focally, along the deep margin, a glassy membrane is evident, even at this magnification; band-like infiltrates of chronic inflammatory cells are focally prominent along the interface between tumor and dermis.


F2Ch29: Tumor cells are few in number; they mostly are individually isolated in a membranous, hyaline matrix. There is some variability in nuclear size and outlines. The patterns are sclerosing but are special due to the nature of the fibrous component - hyaline membranes are interconnected. Nuclei are plump and nucleoli are prominent; chromatin is finely stippled.


F3Ch29: A transition from the sclerosing pattern to the nesting patterns is represented. The nest at the bottom of the field on the right is composed of vacuolated (outer sheath-like) cells. In the area of sclerosis, individual cells and small nests of cells are outined by hyaline membranes. Atypia is moderate.


F4Ch29: In this field, tumor cells and nesting patterns provide a basaloid quality. The tumor cells show variations in nuclear size, staining, outlines, and orientation. Hyaline membranes are a prominent feature.

In chapters 41-45, neoplasms showing features of tricholemmal differentiation are presented.


Note: A new case begins below.

Ch29P21-L3 Irritated Seb K F5-

F5Ch29 (new case that will be continued into Ch31): This lesion is characterized by papillomatosis, irregular acanthosis, and keratin-filled cysts that vary in size. The lesion sits upon the surface of the skin. In some areas, thin cords of squamous cells are complexly interconnected. The papillary dermis is widened and lightly acidophilic, especially in the more papillomatous components. The lesion qualifies as an “irritated seborrheic keratosis.”


F6Ch29: The basic pattern is that of a seborrheic keratosis with prominent papillomatous components. The stroma is condensed and lightly acidophilic. Focally, small, keratin-filled cysts are a prominent feature.


F8Ch29: Small whorls of squamous cells are closely spaced. At least one member of the cluster centrally shows evidence of beginning keratinization. Between the clusters, the keratinocytes are somewhat spindle-shaped. In addition, in areas, the spindle-shaped keratinocytes are loosely attached to their neighbors, a property producing small, irregular clefts. The hyaline deposits in the stroma (green arrows) are deposits of amyloid. Deposits of this type are common in the stroma of seborrheic keratosis, particularly the “irritated” variants.


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