Dermoid Cyst in the Intermandibular Space of a 3-Year-Old Thoroughbred Gelding: A Case Report

Soft tissue swelling located in the intermandibular space is very common in horses and presents a significant diagnostic challenge. Although the possible etiologies of intermandibular swelling are many, dermoid cysts are rarely included within the differential diagnoses list. This may be due to their low prevalence and to the lack of English written literature reporting dermoid cysts in this location in horses. This is the first report describing the clinical signs, diagnosis, and management of a dermoid cyst arising in the intermandibular space of a Thoroughbred horse. In this case, an enlarging soft tissue mass located in the intermandibular space was diagnosed as a dermoid cyst following complete subcutaneous surgical excision and histopathology.     

Orbital fibroma in a horse

An 11-year-old American Quarterhorse gelding presented for moderate periorbital swelling and exophthalmia of the left eye. The menace response, and direct and consensual pupillary light reflexes were absent in the left eye. Conjunctival hyperemia, blepharedema, a mydriatic pupil, resistance to retropulsion, and an increased intraocular pressure were present. A soft-tissue mass could be palpated in the left retrobulbar space by pressing onto the orbit over the supraorbital fossa. Incomplete surgical resection of the mass was performed and histopathologic evaluation was consistent with a fibroma. Normal pupillary light reflexes and vision returned following surgery. The mass has not recurred 14 months after surgery.     

Branchial cleft cyst in a bull.

Branchial cleft cyst was diagnosed in a 6-month-old Angus bull with a large swelling in the distal ventral neck region. A definitive diagnosis could not be attained from results of the clinical examination, radiography, and ultrasonography. Diagnosis was made from histologic examination of the surgically removed mass. Branchial cleft cysts are remnants of the branchial apparatus and are considered rare in domestic animals. The differential diagnosis should include the thymic form of bovine viral leukosis, thymoma, abscess, goiter, and thyroid gland tumors as well as other rare cysts that can develop in the same location.     

Exophthalmus secondary to a sinonasal cyst in a horse

CASE DESCRIPTION: A 13-year-old female Miniature Horse was evaluated for progressive unilateral exophthalmia of the left globe of 3 weeks' duration. CLINICAL FINDINGS: Results of a physical examination were unremarkable. Ophthalmic examination identified exophthalmus of the left globe with complete resistance to retropulsion and mild blepharoconjunctivitis. Computed tomography revealed a large, space-occupying mass within the left caudal maxillary and left conchofrontal sinuses. The mass extended into the left retrobulbar space and contacted the cribriform plate. Trephination yielded copious amounts of turbid yellow fluid. The diagnosis was a sinonasal cyst. TREATMENT AND OUTCOME: Subtotal surgical excision of the cyst via a frontonasal osteoplastic flap was curative, with complete resolution of the exophthalmus. Histologic examination confirmed diagnosis of a sinonasal cyst. There was no evidence of cyst recurrence by 4 months after surgery. CLINICAL RELEVANCE: Sinonasal cyst should be a differential diagnosis for retrobulbar disease in horses. Exophthalmia may be the only clinical finding in horses with a sinonasal cyst.     

一例法斗犬眼角膜皮样囊肿切除及结膜瓣遮盖术

角膜皮样囊肿是一种长在人或动物的角膜、结膜、角巩膜等处被覆毛发的异常皮肤样组织。在人和动物均可见,动物中尤其是在牛和犬中较为常见。角膜皮样囊肿可以引发眼睑痉挛、眼分泌物增加、结膜炎、角膜炎和角膜溃疡等,严重者可导致角膜穿孔和眼球坏死。通过角膜切除术或结膜切除术,切除角膜皮样囊肿并对症治疗的方法来治疗眼部角膜皮样囊肿。以下是在2022年3月接诊的一例幼年法斗犬患有右侧眼角膜皮样囊肿,对患犬实施浅层角膜切除术切除右侧角膜皮样囊肿并用结膜瓣遮盖的手术方法进行治疗,术后恢复良好。     

True dermoid cyst in a Rhodesian ridgeback

A case of a true dermoid cyst in a Rhodesian ridgeback is described. The mass was located in the dorsal cervical midline at the level of the first cervical vertebra, and was resected surgically. In contrast to other types of dermoid sinus described in the literature, the mass did not have a tract connecting it to, nor an opening on to, the surface of the skin. A diagnosis of true dermoid cyst was made.     

Congenital orbital cysts of neural tissue in two dogs

A 3-month-old English Cocker Spaniel and a 6-month-old miniature poodle presented with clinical signs related to an abnormal right eye since birth. In both dogs, the right globe could not be identified and was replaced by a fluctuant intraorbital mass covered by a vascularized mucous membrane. Ultrasonography demonstrated that both masses were cystic structures markedly larger in size than the normal contralateral globes. In both cases, surgical excision revealed a multilobular cyst filling the whole orbital cavity. Histopathologic examination and immunostaining for glial fibrillary acid protein and S100 protein supported a diagnosis of neural cysts associated with ocular dysplasia. The definitive diagnosis was congenital cystic eye and microphthalmos with cyst for the Cocker Spaniel and miniature poodle, respectively. Karyotype was normal in both dogs. Congenital cystic eye and microphthalmos with cyst result from defects in early embryonic life that arise following formation of the optic vesicle and prior to closure of the optic fissure. To the authors' knowledge neither has been reported in the canine species. They should be considered in the differential diagnosis of orbital cysts in dogs.     

Type IV dermoid sinus,intramedullary dermoid cyst and spina bifida in a Cane Corso

A 1-year-old male Cane Corso was presented for progressive hindlimb neurologic deficits, with a history of suspected recurrent meningitis. Physical examination and advanced diagnostic imaging findings were suggestive of a thoracic dermoid sinus extending into the dura mater, and spina bifida. After initial medical treatment, the lesion was surgically excised, and the presence of an intramedullary cyst in continuation with the dermoid sinus was confirmed, requiring partial durectomy and myelotomy for removal. Histopathological examination of the excised tissue confirmed the diagnosis of a dermoid sinus associated with an intramedullary dermoid cyst. After surgery, the dog temporarily declined neurologically but then showed progressive neurological improvement. This report describes presentation and successful surgical treatment of a type IVa dermoid sinus associated with an intramedullary dermoid cyst and spina bifida in a dog.     

Marsupialization and iodine sclerotherapy of a branchial cyst in a horse

A 6-month-old Morgan colt was evaluated because of a 10-cm right-sided retropharyngeal swelling. The swelling was soft and moveable on examination, and palpation did not elicit signs of pain. Radiography revealed a large space-occupying mass ventral to the second cervical vertebra; ultrasonography revealed an anechoic fluid-filled structure with a well-defined hyperechoic capsule. Fine-needle aspiration yielded a viscous amber fluid. Cytologic evaluation indicated that the fluid was an exudate; anaerobic and aerobic bacterial culture did not yield any growth. Histologic examination of a portion of the cyst capsule revealed a connective tissue wall lined by pseudostratified columnar to cuboidal epithelium, consistent with a branchial cyst. The cyst wall was marsupialized to the skin, and iodine sclerotherapy was performed twice daily for 14 days, at which time forceps were introduced into the cyst and the cyst lining was removed. The site was allowed to heal by second intention, but 10 days later, the swelling recurred. An incision was made over the previous marsupialization site, and residual remnants of the cauterized cyst lining were removed with a forceps. The foal did not have any other complications during the subsequent 2 years. Branchial arch cysts are uncommon embryonic anomalies of horses, mice, cats, dogs, and cattle. Results suggest that marsupialization and iodine sclerotherapy may be a viable alternative to surgical excision in horses with branchial cysts; however, the entire cyst lining must be removed at the completion of sclerotherapy to prevent recurrence and abscess formation.     

Dermoid cyst in the tongue of a dog

A German Shepherd Dog presented with recurrent intermandibular and intralingual swelling. Cytological and microbiological findings on fluid aspirated from the mass were consistent with an infected cyst lined by epithelium. The sinus was explored and an epithelium-lined cystic structure was extirpated from the frenulum and body of the tongue. This structure was diagnosed histologically as a dermoid cyst.     

Ocular angiosarcoma in a pony ‐ MRI and histopathological appearance

Ocular angiosarcomas are an infrequent aetiology of exophthalmus in the horse. In the case presented here, a pony was referred with a history of supraorbital swelling, exophthalmus and conjunctivitis of the right eye. Radiographic and ultrasonographic examinations were used for diagnosis; however, the exact definition of the retrobulbar changes could only be made by magnetic resonance imaging (MRI). MRI shows anatomic and physiological detail in both the osseous and soft tissue structures. Only 3 sequences were used in this case: a transverse T2‐weighted and a dorsal high resolution, T1‐weighted gradient echo with multiplanar reconstruction capability pre‐ and post contrast application. This case report suggests that MRI should be used more frequently in the diagnosis of head tumours in horses.     

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.     

Myxosarcoma in the eye and brain in a dog

A male mixed breed dog of unknown age was presented with sudden onset of blindness and a slightly exophthalmic right eye. Ophthalmoscopically, a spherical, pinkish mass protruding from the region of the optic disc into the vitreous was seen in the right eye. Ultrasound and computer tomography demonstrated an extension of the mass into the right retrobulbar space, continuing intracranially to the optic chiasm. Cytologic findings, obtained by ultrasound-guided fine needle aspiration from the retrobulbar space, were consistent with myxosarcoma. On the basis of these findings of a well-delineated mass in the brain stem area, irradiation was planned as the therapy of choice. The dog was treated under general anesthesia using a proton beam at the Paul Scherrer Institute (PSI, Villigen, Switzerland). A curative protocol (56 Gy in 16 fractions over 4 weeks, 3.5 Gy/fraction) was used. Twenty-seven days post radiation therapy the dog was euthanized, as clinical symptoms progressed. Enlargement of the intracranial tumor was seen on a CT study repeated on the day of euthanasia. A gross pathologic and histologic examination were performed and confirmed the diagnosis of a myxosarcoma involving the eye, retrobulbar space of the right side, and the optic chiasm. Post-mortem examination failed to identify any abnormalities or metastases elsewhere in the body.     

Conjunctival dacryops in a domestic shorthair cat

A 1-year-old spayed female domestic shorthair cat with a 1-week history of a conjunctival mass located in the dorsolateral quadrant of the right eye was presented to a referral hospital. Ophthalmic examination revealed a pink, fluctuant, and non-painful cystic swelling of the upper right palpebral conjunctiva. An ocular ultrasound confirmed the presence of a fluid-filled cystic structure that extended into the temporal orbit. The histopathology of the excisional biopsy revealed multiple cysts lined by ductal epithelium along with dilated lacrimal gland ducts and lymphocytic nodules adjacent to the dorsal lacrimal gland; consistent with a diagnosis of dacryops.     

A retrobulbar dermoid cyst with involvement of the sinus in an 18-year old pony

This case report describes a retrobulbar dermoid cyst in an 18-year-old pony with an invasive character into the frontal sinus. CT imaging was important for the appropriate management of this case and the definitive diagnosis was obtained from histopathology. Surgical excision was performed successfully without recurrence 1-year post-operatively. The pony returned to its intended use and previous performance level, although complaints of mild symptoms of headshaking were noted in bright light only.     

Differential diagnoses,investigation, and management of a periocular swelling close to the nasolacrimal duct in a horse – A case report of Dacryops

To describe the differential diagnoses, investigation, and management of a periocular swelling close to the nasolacrimal duct in a horse that was consistent with a nasolacrimal duct dacryops (lacrimal cyst). A 16‐year‐old gelding, Connemara cross presented with a history of a periocular swelling rostroventral medial to the right eye that had been sampled by the referring veterinary surgeon. A cystic lesion was diagnosed following standing computed tomography. Surgical removal of the cystic lesion was performed, and the tissue was submitted for histopathologic and immunohistochemical examination. Surgical removal of the cyst was curative, and there was no recurrence of clinical signs 7 months later. There was a small amount of mineralized material in the center of the cyst. Histopathologic and immunohistochemical examination confirmed a nasolacrimal duct cyst. Dacryops can form in horses as well as other species and appears to have a favorable outcome if surgically removed.     

Congenital ocular dermoid cyst in a river buffalo (Bubalus bubalis) calf

Clinical and histopathological findings of a congenital ocular dermoid cyst, located at the lower eyelid of a river female buffalo (Bubalus bubalis) calf were presented. A soft, fluctuant, non-tender, hyperaemic cystic mass was detected overlaying the left eye. Fine needle aspirate revealed filamentous debris with no malignant cells. The cyst was treated surgically by orbital exenteration and subsequently subjected to histopathological examination. The histopathological study disclosed a conjunctival dermoid cyst. This report is novel, in that; such ocular cyst has not previously been described in river buffalo calves.     

Malignant transformation of an aneurysmal bone cyst in a dog

OBJECTIVE: To report malignant transformation of an aneurysmal bone cyst in a dog. STUDY DESIGN: Case report. SAMPLE POPULATION: Client-owned dog. RESULTS: A 5-year-old male Labrador retriever was diagnosed with an aneurysmal bone cyst of the distal aspect of the right ulna. Surgical curettage resulted in remission of clinical signs for 33 months. Because of recurrence of clinical signs, a distal ulnar ostectomy was performed. Histopathologic examination of the excised specimen revealed a moderately differentiated chondrosarcoma at the level of the bone cyst. Limb function was normal for 17 months until a subcutaneous mass, determined to be a chondrosarcoma, occurred at the level of the shoulder. A right forequarter amputation was performed. CONCLUSIONS: Aneurysmal bone cysts are benign but may be transformed into a malignancy after surgical manipulation. Complete surgical excision should be attempted where possible. In this case, distal ulnar ostectomy was an effective means of preserving limb function and preventing local recurrence of chondrosarcoma.     

Dermoid cysts in camels

In our experience the camel (Camelus dromedarius) seems to be affected more commonly by dermoid cysts as compared to other cutaneous cysts. However, apart from one reference (Monteverde, 1935), the dermoid cyst has not been reported in the camel. This report documents dermoid cysts in identical locations in 11 camels with two camels having bilateral dermoid cysts at the similar site.