PMC5362847_01
Right upper lip swelling at initial examination
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A 9-year-old spayed female domestic shorthair cat was examined for a 3 month history of firm swelling of the right upper lip (Figure 1).
Right upper lip swelling 9 months after initial examination
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Nine months after initial presentation the right upper lip swelling had continued to enlarge with severe exudation and crusting (Figure 2).
Right upper lip after wide surgical excision
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General anesthesia was induced to facilitate wide excision of the affected skin and closure with an advancement flap (Figure 3).
Section of the right upper lip. Multiple epithelial cysts (crosses) invading the dermis, with surrounding severe lymphoplasmacytic, neutrophilic, and mastocytic dermatitis (hematoxylin and eosin x 2)
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Histologic examination of excised tissue demonstrated multiple cysts lined by keratinizing stratified squamous epithelium containing laminated keratin, basophilic debris, individual keratinocytes, and lymphocytes and plasma cells (Figure 4).
Thirteen months after initial examination, prior to euthanasia, demonstrating deviation of the nasal philtrum to the cat's right
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The lip swelling resulted in deviation of the nasal planum (Figure 5).
Sections of the right upper lip. (a) Nests of squamous cell carcinoma (SCC; arrow) adjacent to epithelial cyst (cross) (hematoxylin and eosin x 4). (b) Juxtaposition of epithelial cyst (black arrow), demonstrating squamous keratinization, and SCC (white arrow), demonstrating aberrant keratinocyte differentiation and necrosis (haematoxylin and eosin x 10). (c) Detail of SCC image in (b) (haematoxylin and eosin x 40)
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These features were compatible with SCC (Figure 6).