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Advisor(s)
Abstract(s)
A skin lesion from a 10 year old male Samoyedo, removed from the head, was submitted to the pathology service of the Superior Agrarian School of Viseu. Macroscopically, the lesion corresponded to a skin flap in the form of a bevel centered by a nodule with about 1.8 cm in diameter which, on cut section, had a rounded surface and oval base, totaling 2.6x2.0cm, consisting of little firm tissues with a yellow-white color.
Four 3 µm sections were processed for routine histopathological diagnosis.
Microscopically, the structure observed consisted in a unilocular cyst with unusual features. The cyst was surrounded by large cells, typically squamous like cells, with acidophilic cytoplasm and also many acantholytic cells. The lumen of the cyst was filled with trichilemmal keratin, resulting from the abruptly keratinization of the epithelium, numerous ghost cells, necrotic material and cholesterol clefts. The adjacent dermis was surrounded by an infiltrate rich in plasma cells, lymphocytes and mast cells.
The differential diagnoses to be considered on this case were: acantholytic squamous cell carcinoma, isthmus cyst (tricholemmal cyst), matrical cyst and pilomatricoma. The diagnosis of acantholytic squamous cell carcinoma was excluded because of the absence of keratin pearls; the diagnosis of tricholemmal cyst was excluded due to the abundance of ghost cells, not described in this variant; pilomatricoma, a cystic hair follicle neoplasm, very rich in ghost cells, was excluded only because it is described as a multilocular lesion, in which wall basalloid cells predominates, as well as calcification and foreign body giant cells in the lumen of the cyst.
The diagnosis of matrical cyst was established, although the predominance of large squamous cells type and not the basaloid type, as described as features of these cysts. So it was concluded that the lesion observed was not accurately in any of the follicular cysts or neoplasms described in the literature.
Description
Keywords
dog histopathological diagnosis unilocular cyst trichilemmal keratin acantholytic cells matrical cyst
Citation
Vala H, Santos C, Esteves F, Mesquita J, Nóbrega C, Mega AC, Cruz Paiva R, Oliveira AL (2009). Quisto matrical. Diagnósticos diferenciais. Revista Portuguesa de Ciências Veterinárias. Supl. 104(569-572): 94-95.