Triple dermoid sinus in sacro-caudal region in Rhodesian Ridgeback dog.

Abstract

The aim of this report is to describe a case of a triple dermoid sinus in the sacro-caudal region in an 11-month-old Rhodesian Rhidgeback dog. A clinical examination of the patient revealed a dermoid sinus in the sacro-caudal region. Neurological examination did not show any abnormalities. A blood test and a radiological examination were performed, but the owner refused to perform an MRI. A decision about surgical treatment was made. Two smaller lesions, located 2 cm and 4 cm caudally to the first one, were discovered during skin shaving. The skin around the lesions looked smoother and less pigmented than in the other parts of the body. All three lesions were resected up to the spinous process top or the supraspinous ligament. Histopathological examination showed a typical anatomy of the sinuses and anatomical changes in the skin between them: thinner epidermis and an abnormal shape of hair follicles. In the soft tissue between the ends of the sinus lumina and the supraspinous ligament there were no adnexal structures, such as hair or hair follicles. The sinus type was classified as IIIa. The surgical wound healed without complications. The owner was contacted 14 days and 6 months after surgery, and no signs of complications, pain or gait abnormalities were reported. Dermoid sinus diagnosis is based on medical history, clinical examination and diagnostic imaging. Computed tomography and magnetic resonance imaging are regarded as the most valuable. In many cases, however, their results are inconsistent with those of intraoperative exploration, for example, when a fibrous strand cannot be seen or the depth of the sinus has been inaccurately assessed. Often the depth and type of the dermoid sinus can be exactly assessed only by surgical exploration, so in some cases advanced imaging techniques can be omitted. The most commonly described location of a dermoid sinus is the cervical segment, with multiple lesions present. Only one case of a double dermoid sinus in the sacro-caudal section has been described in the literature. To our knowledge, a triple dermoid sinus at this location and skin anatomy changes in the dorsal medial line between sinuses have not yet been reported.