Stomach, Forestomach, Epithelium - Degeneration
comment:Cytoplasmic vacuolization, cystic degeneration, and vesicle/bulla formation are forms of degeneration of the squamous epithelium that can occur in any squamous epithelium in the body. Vacuolization of the squamous epithelium is characterized by superficial epithelial cells with a pale staining and vacuolated cytoplasm. Associated mucosa may be ulcerated, and epithelial cells may be degenerate or necrotic. Subjacent tissue is variably infiltrated by inflammatory cells. This change may represent a milder change than necrosis and can be observed in studies involving gavage methods. This lesion may also be due to ulcerogenic or anti-inflammatory compounds.
Cystic degeneration is characterized by vacuolization and ballooning swelling of epithelial cells, resulting in rupture of cell membranes to form irregular spaces in the epithelium, potentially leading to development of vesicles or bulla. Associated mucosa may be ulcerated, and epithelial cells may be degenerate or necrotic. Subjacent tissue is variably infiltrated by inflammatory cells. This change may represent a progression of vacuolar degeneration and can be observed in studies involving gavage methods. This lesion may also be due to ulcerogenic or anti-inflammatory compounds.
Bulla are characterized as a localized collection of fluid in or beneath the epithelial layer. Vesicles are <1 cm and bulla are ≥ 1.0 cm. Bulla can form as the result of acantholysis, epidermal or dermal edema, degeneration of basal cells and keratinocytes, or other processes, such as frictional trauma and burns that cause a lack of cohesion between cells. Bulla can lead to erosions and ulceration.
recommendation:Degeneration should be diagnosed and graded when present as a primary lesion. When degeneration is present as a secondary lesion (e.g., when secondary to inflammation) it should not be diagnosed but should be described in the pathology narrative. If the degeneration is a prominent feature of the lesion but is not considered the primary lesion, it may be diagnosed concurrently the primary lesion if the pathologist feels it is warranted. Grading should be based on the degree of cellular swelling and extent and number of areas affected. If both degeneration and necrosis are present, both should be diagnosed and graded. Inflammation should not be diagnosed separately, unless it is a prominent feature of the lesion.
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