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Infundibular Keratinizing Acanthoma
(CANINE INTRACUTANEOUS CORNIFYING EPITHELIOMA, KERATOACANTHOMA)
A benign neoplasm characterized by peripheral proliferation of basaloid epithelial cells with differentiation to squamous epithelium resembling the normal
follicular infundibulum/isthmus.
The diagnosis of keratoacanthoma should be reserved for those tumors of subungual origin.
Gross Appearance:
•Intradermal masses
•Often exophytic
•Varying in size from 0.5-3.0 cm
•Often have a central pore through which a grey keratinous material may be expressed
•Intradermal and subcutaneous component well demarcated from surrounding tissue
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Histology:
•In some tumors a direct association with the follicular infundibulum/isthmus is seen
•Forms a pore through which the tumor communicates with the surface epidermis
•Central lumen filled with keratin
•Lined by large squamous cells with a pale eosinophilic cytoplasm
•Occasional intracytoplasmic keratohyalin granules
•Cells have a central large euchromatic nucleus and distinct cell borders
•At the periphery the tumor cells often form cords only two cells thick
•Differentiate towards the central lumen, form multiple small horn cysts
•Tumor is surrounded by a compressed dermal collagenous stroma
•Often an associated chronic inflammatory cell infiltrate
•Occasionally, tumors exhibit stromal mucinosis
•May also show chondroid or osseous metaplasia
Prognosis:
Good, except in dogs that have multiple tumors, as additional masses develop over time
| Breeds At Increased Risk |
| Breed |
Odds Ratio |
95% Confidence Limit |
Probability |
| Norwegian Elkhound |
30.56 |
23.91 - 39.06 |
0.001 |
| Tibetan Terrier |
14.78 |
7.56 - 28.57 |
0.001 |
| Kerry Blue Terrier |
8.36 |
5.41 - 12.92 |
0.001 |
| Briard |
5.55 |
2.45 - 12.61 |
0.001 |
| Bedlington Terrier |
5.50 |
1.73 - 17.52 |
0.019 |
| Pekingese |
4.20 |
2.65 - 6.66 |
0.001 |
| Yorkshire Terrier |
3.89 |
3.04 - 4.98 |
0.001 |
| German Shepherd |
3.81 |
3.30 - 4.40 |
0.001 |
| Bichon Frise |
3.29 |
2.25 - 4.81 |
0.001 |
| Lhasa Apso |
3.25 |
2.49 - 4.25 |
0.001 |
| Keeshond |
2.39 |
1.43 - 4.00 |
0.002 |
| Samoyed |
2.37 |
1.48 - 3.79 |
0.001 |
| Peekapoo |
2.20 |
1.09 - 4.42 |
0.034 |
| Standard Poodle |
2.09 |
1.51 - 2.90 |
0.001 |
| Shetland Sheepdog |
2.06 |
1.58 - 2.68 |
0.001 |
| Old English Sheepdog |
1.81 |
1.10 - 2.98 |
0.026 |
| Breeds At Decreased Risk |
| Breed |
Odds Ratio |
95% Confidence Limit |
Probability |
| Beagle |
0.50 |
0.31 - 0.82 |
0.004 |
| Golden Retriever |
0.46 |
0.35 - 0.61 |
0.001 |
| Husky |
0.42 |
0.23 - 0.78 |
0.002 |
| Cocker Spaniel |
0.36 |
0.24 - 0.53 |
0.001 |
| West Highland White Terrier |
0.27 |
0.10 - 0.71 |
0.002 |
| Labrador Retriever |
0.24 |
0.17 - 0.35 |
0.001 |
| Rottweiler |
0.10 |
0.03 - 0.30 |
0.001 |
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Sex Distribution (N=1534)
|
| Sex |
Status |
Percent
|
|
|
|
28.8 |
|
|
17.9 |
|
|
|
20.1 |
|
|
33.2 |
(normal sex distribution)
| Anatomic Location (N=1423) |
| Site |
Percent
|
| Back |
16.9 |
| Hindlimb |
13.5 |
| Forelimb |
13.4 |
| Tail |
11.3 |
| Head |
10.3 |
| Neck |
10.0 |
| Multiple |
8.7 |
| Thorax |
8.1 |
| Abdomen |
6.7 |
| Perineum |
1.0 |
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