Fibro-Osseous Lesions Of The Craniofacial Complex In Horses: 30 Cases (2001-2019).

OBJECTIVE: To describe the presentation, diagnosis, treatment, and outcome for horses with fibro-osseous lesions of the craniofacial complex. STUDY DESIGN: Retrospective multicenter case series. ANIMALS: Thirty horses evaluated for fibro-osseous lesions of the skull from January 1, 2001 through December 31, 2019 in four centers. METHODS: Medical records were reviewed for signalment, clinical presentation, histological and diagnostic imaging findings, treatment instituted, and outcome. Long-term outcome information was obtained by owner questionnaire or the medical record. RESULTS: Diagnoses included ossifying fibroma in 20 of 30 horses, osteoma in eight of 30 horses, and fibrous dysplasia in two of 30 horses. Twelve of 30 lesions were diagnosed in horses <1 year old, and 20 of 30 lesions originated from the rostral mandible. The most common treatment was rostral mandibulectomy. Recurrence was not reported after complete excision. Incomplete excision was confirmed in eight horses (four ossifying fibromas, three osteomas, and one fibrous dysplasia), and follow-up information was available for seven horses. Recurrence occurred in one horse, while six horses had long-term resolution of clinical signs. Prognosis for survival and return to use was excellent in 23 horses with long-term follow-up. CONCLUSION: Fibro-osseous lesions were uncommon in this multicenter study; they were most commonly diagnosed in young animals and most frequently affected the rostral mandible. Long-term survival was excellent. CLINICAL SIGNIFICANCE: The definitive diagnosis of fibro-osseous lesions of the craniofacial complex in horses is made from results of histopathology and cannot be determined on the basis of clinical presentation alone. Surgical excision is indicated, and prognosis can be favorable even when complete surgical margins are not obtained.

Surgical Resection of a Parietal Osteoma in a Domestic Ferret Using Advanced Neurosurgical Techniques.

A 3.5 yr old male neutered ferret presented with progressive enlargement of a right dorsocaudal skull mass that had occurred over 18 mo. Computed tomography imaging revealed a large (2.4 × 2.7 cm), well-defined, pedunculated osseous mass arising from the right parietal bone. Cytology was inconclusive, and surgical biopsy was consistent with an osteoma. Further enlargement of the mass occurred over the next 3 mo, at which time surgical intervention was pursued. The patient recovered well, despite the persistence of a bony defect at the former mass site, and no mass regrowth occurred in the 14 mo following the surgical resection. This is one of only two reports in the literature to document the surgical removal of an osteoma in a ferret, and this is the sole case in which a custom apparatus was fabricated for head stabilization, a multiaxis adjustable surgical table was used to improve access to the surgical site, and an ultrasonic scalpel was used for the mass resection.

Modified lateral orbitotomy with combined partial zygomatic arch and vertical ramus ostectomies for excision of a frontal and parietal bone osteoma in a dog.

OBJECTIVE: To describe modifications to the lateral orbitotomy for surgical excision of tumors affecting the frontal, parietal, palatine, or temporal bones. STUDY DESIGN: Case report. ANIMAL: A 5-year-old female spayed American pit bull terrier. METHODS: The dog presented for excision of a bone tumor affecting the right frontal and parietal bones. A modified lateral orbitotomy was performed with combined partial zygomatic arch and vertical ramus ostectomies to increase working space and allow drilling of the calvarium ventral to the mass. RESULTS: The dog tolerated the procedure well, and there were no complications from either the ostectomies or the craniectomy. Histopathological examination was consistent with complete excision of an osteoma. The dog survived 2 years with no recurrence and was euthanized due to an intestinal mass. CONCLUSION: The lateral orbitotomy approach can be modified with combined partial zygomatic arch and vertical ramus ostectomies to increase exposure and working space for resection of tumors affecting the frontal, parietal, palatine, or temporal bones.

Progressive ossifying paranasal sinus mass of suspected traumatic origin in a mare: Surgical treatment and follow-up.

This report describes a case of a multilobular, osseous mass including parts of the right orbit, concho frontal sinus and right ventral and dorsal conchal sinuses that developed after a traumatic insult to the right maxillary sinus 4 years prior to presentation. Surgical removal of the mass including parts of the bony orbit and long-term outcome are reported.

Masse des sinus paranasaux à ossification progressive d'origine traumatique soupçonnée chez une jument : traitement chirurgical et suivi. Ce rapport décrit une masse multilobulaire et osseuse comprenant des parties de l'orbite droite, des cornets nasaux frontaux et des sinus ventral et dorsal droits qui s'est développée après un traumatisme du sinus maxillaire droit 4 années avant la présentation. L'ablation chirurgicale de la masse, incluant des parties de l'orbite osseuse et les résultats à long terme sont signalés.(Traduit par Isabelle Vallières).

Benign and Malignant Proliferative Fibro-osseous and Osseous Lesions of the Oral Cavity of Dogs.

Ossifying fibroma (OF) and fibrous dysplasia (FD) are benign, intraosseous, proliferative fibro-osseous lesions (PFOLs) characterized by replacement of normal bone by a fibrous matrix with various degrees of mineralization and ossification. Osteomas are benign tumors composed of mature, well-differentiated bone. Clinical, imaging, and histologic features of 15 initially diagnosed benign PFOLs and osteomas of the canine oral cavity were evaluated. Final diagnoses after reevaluation were as follows: OF (3 cases), FD (4 cases), low-grade osteosarcoma (LG-OSA) (3 cases), and osteoma (5 cases). Histology alone often did not result in a definitive diagnosis for PFOL. OF appeared as a well-circumscribed, radiopaque mass with some degree of bone lysis on imaging. Most lesions of FD showed soft tissue opacity with bone lysis and ill-defined margins. Low-grade OSA appeared as a lytic lesion with a mixed opacity and ill-defined margins. Osteomas were characterized by a mineralized, expansile, well-circumscribed lesion. Although histologic features of PFOLs were typically bland, the lesions diagnosed as LG-OSA had some features of malignancy (eg, bone invasion or a higher mitotic index). Treatment varied widely. Of the 10 dogs with benign PFOL or osteoma with known outcome (10/12), 9 showed either complete response (6/10) or stable disease (3/10) after treatment. Of the 2 dogs with LG-OSA with known outcome, 1 showed complete response after curative intent surgery, but 1 patient had recurrence after partial maxillectomy. Definitive diagnosis of mandibular/maxillary PFOL is challenging via histopathologic examination alone, and accurate diagnosis is best achieved through assimilation of clinical, imaging, and histopathologic features.

Oral osteoma in 6 dogs.

Medical records of patients with a histopathological diagnosis of oral osteoma were reviewed for information on signalment, body weight, history, clinical signs, physical examination and diagnostic imaging findings, surgical procedure performed, and histopathologic characteristics. Clinical signs related to the mass were noted in 2 dogs. One mass was documented to have been present for > 3-years, 3 of the masses were noted on physical examination, and 2 masses were noted during professional scaling and survey intraoral radiographs. All six masses had radiographic signs of bone proliferation without bone lysis. One case had radiographic root resorption of adjacent dentition. Four of the masses were classified as central osteoma and 2 were classified as peripheral osteoma based on clinical and radiographic findings. Four masses were treated with excisional biopsy that consisted of wide excision (rostral maxillectomy) [n = 1] and 3 had marginal excisions (en bloc resection) [n = 3]. Two of the masses were debulked with subsequent biopsy. There was no indication of recurrence in the cases with excisional biopsy and minimal progression in the cases that had lesions debulked > 5.5-months following surgery.

Successful medical treatment of an orbital osteoma in a dog.

A 6-year-old neutered male German Shepherd-mixed breed with a 2-month history of bilateral conjunctival hyperemia, epiphora, and a firm, slowly progressive swelling of the medial canthal region of the left eye (OS) was examined. Ophthalmic examination OS revealed a firm and smooth mass, extending from the medial canthus toward the medial orbital wall. Indirect ophthalmoscopy revealed indentation of the nasal part OS, which corresponded to the position of the orbital mass. Orbital neoplastic diseases were the main differential considerations. Computerized tomography revealed a bony smooth orbital mass without bone destructive features. Biopsy was performed, and histologic features were suggestive of osteoma. Systemic nonsteroidal anti-inflammatory (NSAID) drugs resulted in complete mass regression and absence of clinical signs for 5 years following initial diagnosis. This report describes the first case of canine orbital osteoma, which was responsive to NSAIDs.

A rare case report of extensive mandibular osteoma corrected by unilateral mandibulectomy: Cytological, radiological, and pathological investigation.

Background: Osteoma is a benign bone tumor that rarely affects animals. The most common bones involved with this tumor included the mandible, maxillofacial bones, and nasal sinuses. Definitive diagnosis is based on pathology findings which allow for differentiation with other bone lesions. Case Description: The patient, a 5-year-old intact male Mongrel dog presented with a huge mandibular mass that involved both the right and left mandible, and led to dental occlusion. The radiography was performed and depicted the intense mass with a well-demarcated edge, a short transitional zone between normal and abnormal bone, and a smooth rounded radiopaque appearance. The investigation according to the fine needle aspiration showed the presence of oval to spindle shape cells with poorly malignancy criteria, fatty cells, reactive osteoblasts, and osteoclasts based on a population of spindle-shaped cells, and low numbers of degenerated neutrophils, bacteria, and few macrophages. Then, the radiographic assessments and cytology findings demonstrated the osteoma and were referred for surgical intervention. A unilateral mandibulectomy was performed, and the lesion was sent to the histopathology laboratory. The histopathology evaluation showed osteocyte proliferation without malignancy features. The osteoblast cells also showed no atypical proliferation that endorses the osteoma tumor. Conclusion: Although mandibular and maxillofacial bone resection in small animals have different tolerations, this patient became a candidate for surgery for future better nutrition and prevention of facial deformity and dental malocclusion. Follow-up after osteoma is one of the most necessary post-operation treatments to check the regeneration of the mass. There are considerable data in this report that should regard this tumor as a possible differential diagnosis for mandibular tumors.

Mandibular Osteoma in a Haflinger Mare: Clinical and Pathological Features.

A 11-year-old, Haflinger breed mare developed a slowly growing mass, protruding on the ventral aspect of the mandible. On palpation, the lesion was pedunculated, very firm, cold and not painful. Radiographic examinations showed a radiopaque, multi-lobular, "mushroom-like" lesion, which arose from the mandibular cortex without involving the bone marrow cavity. Thereafter, the mass was excised for cosmetic purposes. Microscopically, the lesion mainly consisted of bone trabeculae, covered by a thick layer of connective tissue resembling the periosteum. History and clinical findings allowed the temptative diagnosis of mandibular osteoma, which was further supported by diagnostic imaging and pathological features. In particular, the presence of pedunculated lesions arising from the bone surface appeared as highly suggestive of osteoma. Equine osteomas usually affect paranasal sinuses and the rostral mandible and share many similarities with other neoplastic and neoplastic-like conditions, such as ossifying fibroma and fibrous dysplasia. The prognosis is good whenever the neoplasm is fully removed, that depending on the localization and the size of the mass.

Suspected osteoma in an eclectus parrot (Eclectus roratus roratus).

A 7-month-old, male eclectus parrot (Eclectus roratus roratus) was presented with a slow-growing mass over the chest and localized self-trauma to the area. Repeated sternal trauma secondary to an improper wing trim was observed in this case before development of the lesion. Surgical excision of the mass was performed for diagnostic and treatment purposes. On histopathologic examination, the mass was characterized by well-differentiated trabecular bone surrounded by a thin layer of periosteum. These findings were consistent with, but not exclusive to, a diagnosis of osteoma. This benign bone lesion is rare in human and veterinary medicine, with even fewer reports of this condition in avian patients. Trauma to the sternum from falling because of wing clipping was the most likely inciting cause in this parrot.

Congenital Osteoma of the Frontal Bone in an Arabian Filly.

Congenital frontal osteoma has not been previously described in horses. This report records-for the first time-a congenital osteoma of the frontal bone in a 4-month-old Arabian filly. The filly had a frontal hard mass that was present at birth and then showed a slow and continuous growth. This mass appeared as a solitary, painless, oval dense tumor of compact bone, about 2 cm in diameter and 3 cm in length. The tumor was asymptomatic, and the skin over the mass was normal. Radiography revealed a well-defined oval, radio-dense mass projecting from the surface of the right frontal bone with no local invasion. The tumor had a broad-based attachment to frontal bone with normal frontal sinus. The mass caused disfigurement; therefore, it was removed at the owner's request. The mass was diagnosed histopathologically as osteoma. The surgical excision of the osteoma was successful without any complications, and the filly adapted remarkably well after surgery. No recurrence was reported 20 months after the surgery. In conclusion, osteoma should be listed during the differential diagnosis of the congenital craniofacial masses in horses. Early diagnosis of the frontal osteoma guarantees a successful surgical treatment and consequently prevents the future complications.

Pneumocephalus secondary to removal of an osteoma from the paranasal sinuses of a horse.

CASE DESCRIPTION: A 2-year-old Quarter Horse was evaluated because of a progressive left-sided facial deformity and unilateral nasal and ocular discharge. CLINICAL FINDINGS: Physical examination revealed convexity of the left frontonasal region, left-sided nasal and ocular discharge, and decreased air flow through the left nares. Radiography and computed tomography revealed an extensively mineralized mass occupying most of the left paranasal sinuses. TREATMENT AND OUTCOME: The mass was surgically debulked, but complete removal was precluded because the mass was tightly adhered to the frontal and maxillary bones. Results of histologic examination of the mass were consistent with a diagnosis of osteoma. The horse developed transient pyrexia and colic following surgery, and postoperative radiography revealed gas opacities in the lateral ventricles of the brain, consistent with iatrogenic pneumocephalus. However, the horse did not develop any neurologic signs and was performing normally 2 years after surgery. CLINICAL RELEVANCE: Findings reinforce concerns that paranasal sinus surgery in horses can be associated with intracranial complications such as pneumocephalus. In horses with a mass involving the paranasal sinuses, computed tomography may be helpful in determining the boundaries of the mass and formulating a surgical treatment plan.

Three cases of osteoma and an osseous fibroma of the paranasal sinuses of horses in South Africa.

Four horses were presented to the Onderstepoort Veterinary Academic Hospital with histories of facial asymmetry, nasal discharge or obstruction of normal nasal passage airflow. Radiographic examination of the maxillary sinuses of 2 cases revealed well circumscribed, unilateral, mineralised masses; the other 2 cases showed less mineralisation. The masses were accessed for further investigation by surgically created frontonasal bone flaps or trephination of the maxillary sinuses. Diagnosis of osteoma was confirmed histopathologically in 3 of the cases and of ossifying fibroma in the 4th. Two horses were euthanased directly after surgical intervention due to poor prognosis. Osteomas are by nature expansile tumours and follow the complex communication of the sinuses, and therefore are not all amenable to surgical removal. Osseous fibromas are large, solitary, expansile lesions that are rare in all species but reported most frequently in horses. They have an apparent predilection for the rostral mandible of the horse.

A case of benign osteogenic tumour in Homo naledi: Evidence for peripheral osteoma in the U.W. 101-1142 mandible.

The reported incidence of neoplasia in the extinct hominin record is rare. We describe here the first palaeopathological analysis of an osteogenic lesion in the extinct hominin Homo naledi from Dinaledi Cave (Rising Star), South Africa. The lesion presented as an irregular bony growth, found on the right lingual surface of the body of the adult mandible U.W. 101-1142. The growth was macroscopically evaluated and internally imaged using micro-focus x-ray computed tomography (µCT). A detailed description and differential diagnosis were undertaken using gross and micromorphology, and we conclude that the most probable diagnosis is peripheral osteoma - a benign osteogenic neoplasia. These tumours are cryptic in clinical expression, though they may present localised discomfort and swelling. It has been suggested that muscle traction may play a role in the development and expression of these tumours. The impact of this lesion on the individual affected is unknown. This study adds to the growing corpus of palaeopathological data from the South African fossil record, which suggests that the incidence of neoplastic disease in deep prehistory was more prevalent than traditionally accepted. The study also highlights the utility of micro-computed tomography in assisting accurate diagnoses of ancient pathologies.

A nasal osteoma with an acute course in a Japanese Black heifer.

A 14-month-old Japanese Black heifer presented with unilateral epistaxis and mild swelling of the right face. Radiography revealed a mass with increased radiopacity on the right side of the nasal bridge, extending to the left side. Intranasal endoscopy confirmed a large tumor-like structure protruding into the nasal cavity. Following euthanasia, cranial computed tomography (CT) was performed, revealing a tumor 24.3 × 17.5 × 14.8 cm in size. The tumor occupied the entire right nasal cavity and the frontal and sphenoid sinuses. Histopathological examination revealed that the tumor consisted of well-differentiated trabecular bones and loose connective tissue. Based on these findings, a diagnosis of osteoma was established. This report describes a case of osteoma with an acute course in a Japanese Black heifer.

An unusual mucinous osteoma with features of an ossifying fibroma in the nasal cavity of a horse.

A 4-month-old Warm-blooded colt presented with facial distorsion and an abnormal respiratory noise of 2 weeks' duration. A proliferative mass was found endoscopically and by computer tomography. Clinical differential diagnosis included cyst formation of the concha, malformation and neoplasia. Euthanasia was followed by post-mortem examination, which revealed a well-circumscribed, semi-solid, jelly like structure, measuring 14.5 x 9.0 x 12.0 cm, in the left posterior nasal cavity extending into the left frontal and maxillary sinus. Histologically, the mass consisted of trabeculae of woven bone, focal lamellar bone and fibroblast proliferation within a moderate fibro-vascular stroma. Abundant mucin production was noted within areas of fibroblastic differentiation. Some areas contained irregularly shaped spicules of osteoid rimmed by osteoblasts, randomly distributed within a moderately vascularized, fibro-osseous stroma. On the basis of the histopathological features, a nasal mucinous osteoma with focal ossifying fibroma-like structures was diagnosed.

Multifocal osteoma cutis in a golden retriever.

A 10-year-old, spayed female, obese golden retriever, presented for immune-mediated thrombocytopenia, was successfully managed with the administration of vincristine and prednisone. However, 6 mo after discontinuing corticosteroid therapy because of suspected iatrogenic hyperglucocorticoidism, the patient was presented with multiple, firm, bilaterally symmetric, dermal masses composed histologically of differentiated cortical bone.

Exophthalmia associated with paranasal sinus osteoma in a Quarterhorse mare.

An 11-year-old Quarterhorse mare developed a paranasal sinus osteoma that extended into the right orbit and led to ipsilateral exophthalmia. Although the tumor was radiographically evident in the paranasal sinuses, ultrasonography was used to demonstrate extension of the tumor into the retrobulbar space, and endoscopy was used to identify its extension into the nasopharynx. Biopsies were obtained using both fine-needle aspiration and paranasal sinus trephination. Despite numerous antemortem diagnostic tests, only postmortem histologic analysis of the mass afforded the diagnosis of osteoma.

Osteoma in the skull of a sheep.

An osteoma located in the frontal bone and nasal cavity is described in a 4-year-old dairy sheep with respiratory difficulty and progressive emaciation. The mass was hard, formed by bone, and caused compression of the ethmoidal labyrinth. Microscopically, the tumour was characterized by trabeculae of woven bone, frequently coexisting with lamellar bone composed of fine fibres, lined by osteoblasts and surrounded by a fibrous stroma. A severe chronic inflammation was seen in the nasal mucosa. Differential diagnosis is discussed, particularly in relation to ossifying fibroma.

Fracture-associated osteogenic sarcoma and a mandibular osteoma in two goats.

An osteogenic sarcoma in association with a previously repaired fracture site and an osteoma were recorded in two aged Toggenburg and Toggenburg-cross goats. In one animal, five years after the surgical repair of a comminuted mid-shaft humeral fracture with an intramedullary pin, a sarcoma with osteoid production developed at the fracture site. A review of records revealed the previous occurrence of a mandibular osteoma inducing both subluxation of the temporal mandibular joint and contralateral mandibular deviation in a second animal. Such lesions are rarely documented in goats.