Definition
Keratoacanthoma (KA): a low grade growth of the epidermis that originates in the hair follicle and progresses rapidly. Also referred to as: “self-healing,” or “pseudocarcinoma.”
Clinical signs
KA presents with a characteristic appearance of a crateriform lesion, a central keratinous plug, and edges of normal skin extending over the central keratinous crater.
Etiology
Keratoacanthoma is a typically benign epidermal tumor that may resemble squamous cell cancer both visually and histologically. But unlike squamous cell cancer, it is usually benign. This type of lesion often forms a keratin horn that gives it a characteristic appearance.
Factors that may contribute to KA include: immunocompromised status, trauma, and genetic predisposition.
A keratoacanthoma may occasionally progress to multiple growths, may enlarge, may become aggressive locally. However, metastasis to distant organs is very rare.
The cause of keratoacanthomas is unknown.
Prognosis and outcome for a rat diagnosed with keratoacanthoma is good.
Photos and case history are provided in the following figure.
- Fig. 1: Keratoacanthoma: photos and case history
Diagnostics
Exact diagnosis can be performed by biopsy and pathological examination.
Treatment
Keratoacanthomas can be surgically removed, but is often known to involute and resolve spontaneously. While this type of tumor does tend to resolve on its own after several weeks to months (spontaneous involution), the resulting wound may sometimes require suturing, and may or may not leave a scar.
Although lotions and ointments do not help to resolve this growth, if surrounding tissue is cracked, irritated or inflamed, the vet may choose to treat with applications of an antimicrobial ointment.
If the decision is made for surgical intervention, the procedure may be one of surgical excision, cryosurgery (a controlled type of tissue freezing), or electrocautery, depending on the location and involvement of the growth.
In the event of surgery, the inclusion of a post-op broad-spectrum antimicrobial is encouraged. The vet may also consider providing post-op pain control with oral torbugesic or banamine.
For more information on antimicrobials or analgesics refer to the Rat Medication Guide.
Nursing Care
Keep the area clean.
Apply any ointments your vet may prescribe.
If surgery is an option:
- Provide hospital cage during recovery, or if there are concerns that cage mates may groom sutures or wound site.
- Provide clean bedding, such as cloths or ink-free paper towels, daily. Avoid litter-type bedding post-op, until healed, to prevent the chance of wound contamination or infection.
- Provide additional warmth using a hot water bottle or heating pad, if needed, in order to maintain body temperature within normal limits. Use low heat settings and place under one half of cage to ensure rat does not become overheated or dehydrated.
- Medicate for post-op pain as needed.
- If prescribed give antimicrobials as ordered.
- Body wrap may be required if thread sutures are used.
- In the event there is dried or excess drainage, the incisional site may be cleaned with a moistened cotton swab using warm water or normal saline.
- For 24-48 hours post-op, feed iron-rich foods to prevent anemia (cooked liver, scrambled or hard-boiled eggs).
- Contact vet if any of the following are observed: swelling, inflammation (redness) or pain at the incision site, or signs of increased weight loss, lethargy, or changes in habits.
Outcome
Resolution or removal of keratoacanthoma with minimal scarring.
If KA reoccurs discuss additional treatment with your vet.
Prevention
There is no known prevention for keratoacanthomas.
Posted on January 16, 2006, 18:11,
Last updated on June 15, 2008, 20:03
| Neoplasia
