Branchial Cyst Excision in a Labrador

 

    Dermoid cysts are complex congenital cysts that form long before birth. Dermoid cysts occur when ectodermal tissue i.e., skin, and adnexal skin structures collect under the skin during fetal development. These cysts may contain hair, teeth, or even nerves. They usually appear at birth and grow very slowly or usually remain the same size.

    Branchial cleft cysts are similar pathologies when the tissues on either one or both sides of the neck develop abnormally. These can sometimes, but need not necessarily communicate with the skin through an opening called branchial cleft sinus tract.

    Dermoid cysts are commonly seen in the eyes of dogs, but this was the first case where I found a similar pathology located internally. A 3-year-old Labrador had a soft fluctuating lemon-sized swelling ventral to the right submandibular lymph node. It was clinically insignificant during previous visits and an attempt to aspirate the contents turned out to be futile. The content was a brownish liquid with visible fat globules. 5 months later, the dog was presented with a complaint of scratching at the site.  

Images showing the site of pathology and the aspirate obtained. The dog is facing towards your right and the ventrolateral neck is painted with Povidone Iodinebeforeo aspiration. 

Microscopy of the aspirated fluid revealed mainly exfoliated keratinized cells along with some epidermal debris

    Surgical exploration and excision was planned. Although the fluctuating swelling was palpable and visible as a bulging eminence over the skin, it was deeply situated and required careful dissection around vital neurovascular structures of the neck to fully isolate the cyst and excise it.

Intraoperative image showing the cyst which is exteriorized after blunt dissection of the superficial fascial planes and postoperative image after application of simple interrupted sutures. 

    Dissection of the cyst after the surgery revealed similar fluid to that obtained through aspiration. A layer of skin with hair follicles was found loosely attached to the inner layer of the cyst which could easily be separated. A section of the same was sent for histopathology.

Image showing the excised cyst in relation to a 3ml syringe and cyst after incision and turning it inside out

Video showing the dissection of the excised branchial cyst

    The histopathology report stated “Section studied shows tissue fragments lined by stratified squamous epithelium with separately lying fragments of keratin debris. Adnexal structures are noted in the wall. The section is negative for granuloma or malignancy. Features are suggestive of dermoid cyst.”

  

Images showing the healing of surgical wound 10 days post-surgery and after suture removal

  I couldn’t find many clearly defined and published reports of either condition in dogs and hence is difficult to differentiate between the two cysts. However, considering the location of the cyst and the histopathology report, I believe what I excised was a branchial cyst. Complete surgical excision is the only foolproof modality advised for the treatment of branchial cysts.