True dermoid cyst in a Rhodesian ridgeback

Locally extensive follicular hamartomas with concurrent follicular cysts and dermoid cysts on the head of a dog

A 5-month-old, male intact Australian shepherd dog was presented with nodular lesions affecting the dorsal head. A locally diffuse form of follicular hamartomas, with concurrent dermoid cysts and follicular cysts, was diagnosed by histopathological examination. Complete surgical excision of the affected skin and closure with a subdermal plexus advancement flap led to long-term resolution.

Case Report: Surgical Treatment of Type IV Spinal Dermoid Sinus in a Shiba Inu

A 2-year-old spayed female Shiba Inu was presented with progressive non-ambulatory bilateral paraparesis, back pain, and urinary incontinence. CT and MRI revealed multiple vertebral malformations and type IV dermoid sinus. Hemilaminectomy was performed in T1–T5 to remove the dermoid sinus and granulomatous lesion that infiltrated into the spinal cord parenchyma. Histopathological examination of the excised tissue revealed type IV dermoid sinus with granulomatous meningomyelitis. After surgery, back pain was resolved, and the dog recovered ambulation and voluntary urination at the time of follow-up 4 months after surgery.

Prevalence and segregation analysis of dermoid sinus in Rhodesian Ridgebacks

Rhodesian Ridgebacks a characteristic dorsal hair ridge with backward-growing hair. Dermoid sinus was reported as a prevalent congenital condition in ridged dogs and as a sporadic finding in other dog breeds. This condition presents as a tubular skin indentation to variable degree into underlying tissues on the dorsal midline or cranial or caudal to the ridge. In the present study, data from 12,700 puppies born to 1622 litters from Rhodesian Ridgebacks in 2001-2019 in Germany were analysed for the prevalence of dermoid sinus and ridgless animals. Data from litters with dogs segregating for dermoid sinus were used to test compatibility with an autosomal recessive Mendelian trait. Overall prevalence of dermoid sinus in 12,700 puppies was 2.53%. In 1269 litters with only ridged animals, prevalence was 2.81%. In 46 litters, segregation of ridgeless dogs was observed, and two ridgeless animals had dermoid sinus. The overall trend for dermoid sinus prevalence significantly decreased by -0.099% per birth year, whereas a significant trend for ridgelessness was not found. A more complex genetic determination for dermoid sinus seems likely, due to the insufficient fit of a monogenic autosomal recessive model of inheritance and a heritability estimate of 0.78 ± 0.11. Genetic correlation with ridgelessness was -0.11. In conclusion, our data revealed a decreasing trend for the prevalence of dermoid sinus and a complex genetic basis for this condition. The ridge locus was unlikely to determine the expression of dermoid sinus, given the low segregation ratio for dermoid sinus in a population selected for the ridge allele.

Comparison of inherited neural tube defects in companion animals and livestock

Neural tube defects (NTDs) are congenital malformations resulting from the improper or incomplete closure of the neural tube during embryonic development. A number of similar malformations of the protective coverings surrounding the central nervous system are also often included under this umbrella term, which may not strictly fit this definition. A range of NTD phenotypes exist and have been reported in humans and a wide range of domestic and livestock species. In the veterinary literature, these include cases of anencephaly, encephalocele, dermoid sinus, spina bifida, and craniorachischisis. While environmental factors have a role, genetic predisposition may account for a significant part of the risk of NTDs in these animal cases. Studies of laboratory model species (fish, birds, amphibians, and rodents) have been instrumental in improving our understanding of the neurulation process. In mice, over 200 genes that may be involved in this process have been identified and variant phenotypes investigated. Like laboratory mouse models, domestic animals and livestock species display a wide range of NTD phenotypes. They remain, however, a largely underutilized population and could complement already established laboratory models. Here we review reports of NTDs in companion animals and livestock, and compare these to other animal species and human cases. We aim to highlight the potential of nonlaboratory animal models for mutation discovery as well as general insights into the mechanisms of neurulation and the development of NTDs.

Cystic Abnormalities of the Spinal Cord and Vertebral Column

Cystic lesions of the vertebral column and spinal cord are important differential diagnoses in dogs with signs of spinal cord disease. Synovial cysts are commonly associated with degenerative joint disease and usually affect the cervical and lumbosacral regions. Arachnoid diverticulum (previously known as cyst) is seen in the cervical region of large breed dogs and thoracolumbar region of small breed dogs. This article reviews the causes, diagnosis, and treatment of these and other, less common, cystic lesions.

Spinal dermoid sinus in a Dachshund with vertebral and thoracic limb malformations

BACKGROUND

Dermoid sinus is an uncommon epithelial-lined fistula that may be associated with vertebral malformations. In humans, Klippel-Feil syndrome (KFS) is a rare condition characterized by congenital cervical vertebral fusion and may be associated with other developmental defects, including dermoid sinus. The present case report describes an adult Dachshund with cervical and cranial thoracic vertebral malformations as well as thoracic limb malformations resembling KFS with a concurrent type IV dermoid sinus.

CASE PRESENTATION

A 1.5 year-old Dachshund with congenital thoracic limbs deformities and cervical-thoracic vertebral malformations presented with cervical hyperesthesia, rigidity of the cervical musculature and tetraparesis. Neurologic, radiographic, and computed tomography (CT) (2D, 3D, CT fistulography) examinations revealed skeletal anomalies, a dermoid sinus in the cranial thoracic region and epidural gas within the vertebral canal. Surgical resection and histopathological evaluation of the sinus tract were performed and confirmed a type IV dermoid sinus. The clinical signs progressively recovered postoperatively, and no recurrent signs were observed after 6 months of follow-up.

CONCLUSIONS

Cervical vertebral malformations associated with limbs anomalies have not been reported in dogs and may represent a condition similar to KFS in humans. KFS can occur concurrently with other congenital conditions including dermoid sinus and should be included among the complex congenital anomalies described in dogs.

Multiple dermoid sinuses of type Vb and IIIb on the head of a Saint Bernard dog

Dermoid sinus, a congenital malformation of neural tube development, has been reported in humans and several animal species including dogs. It is typically found in the dorsal midline and commonly occurs in the Rhodesian Ridgeback breed. A case of multiple dermoid sinuses in the fronto-occipital region is described. An 11-month-old, intact female Saint Bernard dog was presented with a 2 day history of discharge from a large irregular subcutaneous mass in the fronto-occipital region. The dog was otherwise healthy. The dog had two circular skin lesions (approximately 4 × 4 and 4 × 2 cm diameter) surrounded by multiple irregular elevated masses. The masses had multiple small openings on the skin surface with tufts of hair protruding from the apertures. The masses were surgically removed, and the diagnosis of multiple dermoid sinuses was confirmed by histological examination. Histopathological examination showed multiple, variably sized, spherical to tubular cysts expanding the dermis and subcutis. Cysts were filled with hair shafts and lamellar keratin and were lined by a stratified squamous epithelium. Sebaceous and apocrine gland adnexal structures were also observed. To the best of our knowledge, this is the first reported case of multiple dermoid sinuses of two different types in the head of a Saint Bernard dog.

Intestinal dermoid cyst in a German shepherd dog

A two-year-old male German shepherd dog was admitted to Shahid Bahonar Veterinary Hospital with clinical signs that included lethargy, anorexia, vomiting, abdominal pain and dehydration. Physical examination revealed nothing significant. Routine paraclinical tests only revealed a stress leukogram. Radiography revealed a mass in the stomach. Whilst performing a laparotomy, the surgeon observed an unusual mass in the subserosal layer of the proximal part of the jejunum. The histopathology of the mass revealed some scattered sebaceous and sweat glands associated with the cyst wall that confirmed the diagnosis of a dermoid cyst. Intestinal dermoid cysts are very rare and to our knowledge this is the first report of an intestinal dermoid cyst in a dog.

A quadrigeminal dermoid cyst with concurrent necrotizing granulomatous leukoencephalomyelitis in a Yorkshire Terrier dog

A 2-year-old female Yorkshire Terrier dog presented with neurological deficits. Magnetic resonance imaging revealed an 8 mm in diameter mass centered left of midline arising from the quadrigeminal cistern, with a fatty or proteinaceous content. A further fat signal intensity focus was present in the tip of the temporal horn of the right lateral ventricle, in keeping with a "floating" fat embolus within the cerebrospinal fluid. A ruptured dermoid cyst was diagnosed. Within the frontal lobe on both sides were ill-defined and extensive high T2 signal areas, with mass effect within the white matter, and asymmetrical contrast enhancement following intravenous injection of gadolinium. Postmortem gross and histological examination confirmed the mass in the quadrigeminal cistern to be a dermoid cyst. In addition, severe multifocal necrotizing granulomatous leukoencephalomyelitis was found in the corona radiata and spinal cord. The relationship between these 2 pathologies is discussed.

Nasal dermoid cyst extending through the frontal bone with no sinus tract in a Dalmatian

A Dalmatian was presented with a subcutaneous swelling in the dorsal midline between the eyes. No opening in the skin was identified at the dorsal nasal planum and there was no discharge. Positive contrast sinography showed contrast material filling a cyst that extended to the frontal bone. At surgery, the cyst had a tubular shape and was embedded in a fibrous dermal tissue strand running into the bony nasal septum. The nasal dermoid sinus cyst was surgically removed by limited dorsal rhinotomy, followed by excision of the remaining strand from a bony recess in the lamina perpendicularis ethmoidalis. It is proposed that this nasal dermoid cyst that extends through the frontal bone with no sinus tract is classified as a type V subtype c.

Case report: Spinal dermoid sinus in a Burmese cat with paraparesis

A 2-year-old, male, Burmese cat was evaluated for chronic progressive hindlimb weakness, ataxia and urinary incontinence. Radiographic examination, myelography and magnetic resonance imaging defined congenital vertebral anomalies and a space-occupying intradural, extramedullary mass. A dermoid sinus was subsequently identified dorsal to the affected spine. Surgical excision of the tract necessitated a dorsal laminectomy and removal of a 1-cm diameter intradural dermoid sinus 'cyst' that contained hair and sebaceous debris. The cat recovered hindlimb function after surgery and remains asymptomatic 50 months after surgery except for a persistent inability to urinate voluntarily.

Ventral intraspinal cysts associated with the intervertebral disc: magnetic resonance imaging observations in seven dogs

OBJECTIVE

To report clinical and diagnostic imaging features, and outcome after surgical treatment of ventral intraspinal cysts in dogs.

STUDY DESIGN

Retrospective study.

ANIMALS

Dogs (n=7) with ventral intraspinal cysts.

METHODS

Clinical signs, magnetic resonance imaging (MRI) findings and surgical findings of 7 dogs and histologic findings (1 dog) with intraspinal cysts associated with the intervertebral disc were reviewed.

RESULTS

Ventral intraspinal cyst is characterized by: (1) clinical signs indistinguishable from those of typical disc herniation; (2) an extradural, round to oval, mass lesion with low T1 and high T2 signal intensity on MRI, compatible with a liquid-containing cyst; (3) cyst is in close proximity to the intervertebral disc; and (4) MRI signs of disc degeneration. Although the exact cause is unknown, underlying minor disc injury may predispose to cyst formation.

CONCLUSION

Intraspinal cysts have clinical signs identical to those of disc herniation. Given the close proximity of the cyst to the corresponding disc and the similarity of MRI findings to discal cysts in humans, we propose the term "canine discal cyst" to describe this observation.

CLINICAL RELEVANCE

Discal cysts should be considered in the differential choices for cystic extradural compressing lesions.

Bilateral parieto-occipital dermoid sinuses in a Rottweiler

Bilateral dermoid sinuses were identified on the parieto-occipital region of a Rottweiler. Diagnosis was confirmed by histological examination after successful complete surgical resection. The dermoid sinuses were independent with separate tracts. This unusual parasagittal location can be explained by craniofacial development: dermoid sinuses on the head could occur along the lines of embryological fusion and not only in the sagittal plane. A hypothesis of an origin at the level of the suture between the parietal and interparietal bones is possible in this case.

Inheritance of dermoid sinus in the Rhodesian ridgeback

OBJECTIVES

TO define the mode of inheritance of dermoid sinus.

METHODS

A chi-squared analysis was performed on data from 46 litters produced between 1990 and 2001. Data were corrected to avoid bias in the segregation ratio.

RESULTS

In data from 57 litters (n=492), 82 dermoid sinus positive offspring were observed. The frequency of affected offspring in the Swedish Rhodesian ridgeback population is estimated to be between 8 and 10 per cent.

CLINICAL SIGNIFICANCE

Bias in heredity pattern may be caused by undetected dermoid sinus type V. Improved clinical diagnosis of all dermoid sinus types is therefore crucial.

Epidermal (infundibular) and dermoid cysts in the dorsal midline of a three-year-old thoroughbred-cross gelding

Epidermal (infundibular) and dermoid cysts are unusual in the horse in contrast with other species. The diagnosis and treatment of six lesions in the dorsal midline of a three-year-old Thoroughbred-cross gelding is described. The lesions were believed to be congenital and presented asymptomatically but required attention because five of them were in the saddle region, thus preventing ridden exercise. Under general anaesthesia, the cysts were excised and subsequently examined histologically. The horse recovered uneventfully. This report is novel in that such midline cysts have not previously been described outside Australia and North America.