By David Duclos, DVM, DACVD, For The Education Center
Originally Published In Veterinary Practice News, January 2018 – Download as a PDF
Nodular sebaceous gland hyperplasia, a focal, nonneoplastic cutaneous lesion, is the overgrowth of sebaceous cells and the most common sebaceous gland disorder in dogs. Older dogs are at a greater risk of developing nodular sebaceous gland hyperplasia. Miniature schnauzers, beagles, poodles, and cocker spaniels are predisposed to nodular sebaceous gland hyperplasia.
Nodular sebaceous gland hyperplasia typically occurs as solitary, small circular nodules (0.1 – 0.5 cm in diameter), often with a shiny, alopecic, or scaly surface. Sometimes sebaceous gland hyperplasia nodules easily get ulcerated, may have oily/waxy discharge, and display changes in pigmentation.
The treatment of nodular sebaceous gland hyperplasia in dogs consists of the surgical removal of the tumors.
Histiocytomas are fairly common, benign tumors formed with histiocytes of Langerhans cell origin. Histiocytomas appear as solitary, small, firm, dome- or button-shaped nodules. The nodules are typically rapidly growing and painless.
They can occur in any breed, with boxers and bull terriers more predisposed to histiocytomas. Typically dogs younger than 2 years of age are affected. No gender predisposition has been noted.
Histiocytomas grow rapidly in the first stages of formation—one to four weeks. They may regress spontaneously and resolve over time, but if they are ulcerated, bleeding, itchy or secondarily infected, surgical removal is recommended.
CO2 laser surgery
In my clinic, I use the flexible hollow waveguide fiber CO2 laser to surgically remove soft tissue growths. This technology allows ablating tumors quickly, providing control over intraoperative bleeding. Another benefit of laser surgery is that there is no need to close the surgical site in case of superficial cutaneous lesions. Moreover, the laser allows treating multiple lesions during a single visit, as in one of the cases described in this article.
VetScalpel®, a 45-watt continuous wave (CW) /30-watt SuperPulse (SP) flexible hollow waveguide CO2 laser with a tipless adjustable spot size handpiece set to 0.8 mm focal spot size (by Aesculight®, Bothell, Wash.) (Figures 1A and 1B).
Initial laser settings (higher power) for both nodular sebaceous gland hyperplasia removal and histiocytoma removal:
12 W, SP, repeat mode, 29 Hz; the laser pulse ontime is 25 msec and 8.7 W of average power is delivered to the target tissue.
Procedure 1: Nodular sebaceous gland hyperplasia removal
Bella, a 12-year-old female, spayed pit bull terrier dog mix, was brought in with a small round scaly bump on the left hind leg (Figure 2A). The bump was diagnosed as a focal nodular sebaceous gland hyperplasia. The owners requested its removal.
The surgery was performed under local anesthesia.
More power is typically required to ablate sebaceous gland hyperplasia at first. The mass was ablated in quick overlapping strokes with the laser beam directed perpendicular to the target tissue (Figure 2B). Between laser passes, the surgical site was wiped with a salinesoaked gauze pad and examined. Insignificant bleeding encountered after the first laser pass was stopped by defocusing the laser beam (this was achieved by increasing the distance between the nozzle and the target tissue). The pulse duration was decreased to 20 msec and average laser power was reduced to 4 W; several more laser passes were performed to clean up the deep part of the lesion. The laser pulse duration was now shortened to 15 msec and the average power was decreased to 3 W. Another laser pass was made and the site was blotted with a saline gauze pad to ensure the complete removal of sebaceous tissue (Figure 2C). With the final pass a protective layer of coagulated tissue was created (Figure 2D). The resulting tissue defect was left to heal by secondary intention. No post-operative care was prescribed.
Procedure 2: Removal of histiocytoma
Tucker, an 11-year-old male, neutered boxer dog, was brought in with a solitary, 0.5 cm in diameter, buttonshaped, elevated lump located close to the edge of the left pinna (Figure 3A). The tumor was alopecic and pink. The owners brought the dog to the clinic alarmed by the tumor’s rapid growth. Diagnosis of histiocytoma was made and it was decided to remove the tumor with the CO2 laser.
The procedure was performed under general anesthesia.
After the tumor surface was initially ablated at the highest power setting (Figure 3B), the surgical site was gently blotted with saline soaked gauze. The average power was then decreased to 1.6 W and another laser pass was made (Figure 3C). The site was blotted and the power was then reduced again to 0.8 W. The rest of the tumor was ablated in overlapping sweeping strokes. After each laser pass the surgical site was wiped with saline soaked gauze; but after the final pass, the surgical wound was not wiped (Figure 3D shows immediately postoperative appearance of the surgical site). No sutures were needed.
Note: During the same visit, a small hemangioma was removed from the patient’s trunk (Figure 4A). The ability of the CO2 laser to achieve hemostasis allowed removing it bloodlessly in just a few seconds and without sutures (Figure 4B). Again, initially, the higher power setting was used (3.2 W of average power in the repeat SuperPulse mode). For the final laser pass, the average laser power was reduced to 0.8 W.
No postoperative care was prescribed for the ablated lesions.
Soft tissue growths were easily ablated with the VetScalpel® CO2 laser. The procedures were quick, and the surgical defects were left to heal by secondary intention. Due to its ability to coagulate small blood vessels (less than 0.5 mm in diameter), the laser provided efficient hemostasis throughout the procedures, which ensured good visibility and precise tissue removal with excellent cosmetic outcome. Moreover, the laser allowed for fine adjustments in power and pulsing settings during the surgeries with a simple push of a button on the touch screen. The great control afforded by the VetScalpel® CO2 laser enables the surgeon to remove target tissue, while avoiding unnecessary damage to healthy adjacent structures.
Dr. Duclos is a small-animal practitioner in Lynnwood, Wash., where he is the owner and clinical dermatologist at the Animal Skin & Allergy Clinic. He completed his residency in veterinary dermatology at the University of Pennsylvania. He is an associate clinical instructor for the Western University College of Veterinary Medicine in Pomona, Calif., and teaches senior veterinary students as externs at his clinic. He frequently hosts veterinary students from other Veterinary Medical Colleges around the US, and from veterinary colleges in Europe who are seeking to learn about the specialty of veterinary dermatology during their third and fourth year of veterinary school. In addition, Dr. Duclos teaches veterinary residents in dermatology who are seeking to learn more about laser surgery for two- to four-week externships sponsored by the American College of Veterinary Dermatology. He recently has begun to take part in the One Health initiative, recognizing that the health of people is connected to the health of animals and the environment. The goal of One Health is to encourage the collaborative efforts of multiple disciplines working locally, nationally, and globally to achieve the best health for people, animals, and our environment. He authored a number of book chapters and scientific papers on various subjects in veterinary dermatology. He extensively lectures in the US, Canada, and Europe. Dr. Duclos is well known in the veterinary dermatology specialty for his expertise in CO2 laser surgery and for his interest in clinical photography.
This Education Center article was underwritten by Aesculight of Bothell, Wash., the manufacturer of the only American-made CO2 laser.