Use of magnetic resonance imaging and histopathologic findings for diagnosis of an aneurysmal bone cyst in the scapula of a cat

Percutaneous doxycycline sclerotherapy in a horse with a mandibular aneurysmal bone cyst

OBJECTIVE

To describe the use and outcome of sclerotherapy with intralesional doxycycline foam in a horse with a mandibular aneurysmal bone cyst.

STUDY DESIGN

Case report.

ANIMALS

Client-owned 1 year old Standardbred filly.

METHODS

The horse presented for progressive mandibular swelling. A 10 mg/mL doxycycline foam was prepared for intralesional injection. Three doses were injected into the lesion under computed tomographic guidance at 6 and 15 weeks after initial treatment. Volume reduction was monitored after each treatment with 3D volumetric rendering and region of interest segmentation using commercially available software.

RESULTS

The volume of the lesion decreased from 458.7455 cm³ before treatment, to 363.3101 cm³ at 6 weeks, 273.5855 cm³ at 15 weeks, and 247.2316 cm³ 6 months later, resulting in a total reduction of 54% of the initial volume. Bone formation was noted in the lesion. No adverse effects related to doxycycline foam injections were noted. The mandibular swelling was resolved after treatment.

CONCLUSION

Intralesional doxycycline sclerotherapy was shown to be efficacious in reducing the volume of the aneurysmal bone cyst in the horse presented in this report. There was complete resolution of mandibular swelling with no side effects related to the intralesional injections.

Tarsometatarsal stabilization after metatarsal bone amputation for treatment of an aneurysmal bone cyst in a cat

CASE DESCRIPTION

A 5-year-old 4.0-kg (8.8-lb) castrated male domestic shorthair cat was referred because of grade 4/5 left hind limb lameness and swelling in the region of the second metatarsal bone of that limb.

CLINICAL FINDINGS

Computed tomography revealed an expansile osteolytic lesion of the second metatarsal bone associated with a periosteal reaction on the third metatarsal bone. There was no evidence of metastases.

TREATMENT AND OUTCOME

Amputation of the second and third metatarsal bones was performed but resulted in medial instability of the remaining metatarsal bones. The instability was treated by placing a loop of 2-0 monofilament, nonabsorbable suture from a screw placed in the distal row of the tarsal bones to a tunnel in the proximal metaphysis of the fourth metatarsal bone. Clinical reevaluation of the cat 7, 15, 30, 60, 90, and 210 days after surgery and radiographic reevaluation 90 and 210 days after surgery showed complete recovery of the cat. The implants were removed at the time of the 7-month reevaluation. Clinical evaluation 18 months after implant removal showed the treated joint to be stable.

CLINICAL RELEVANCE

The surgical stabilization technique described here provided medial stability of the tarsometatarsal joint after amputation of the second and third metatarsal bones. This method may be an alternative to arthrodesis while maintaining articular function in cats.

Aneurysmal bone cyst in the pelvis of a cat: successful outcome of partial iliectomy with limb preservation

Case summary

A 3-year-old spayed female domestic shorthair indoor cat presented with a 3-week history of pain from the pelvic region. Physical examination revealed pain elicited on palpating the pelvic area and right hip. Radiographs and CT showed an expansile, osteolytic process with intact cortex in the right wing of the ilium. CT revealed a monostotic and soft tissue-attenuating process with clear margins. Preoperative histopathological diagnosis of aneurysmal bone cyst was made from incisional biopsies. The cyst was removed en bloc with limb-sparing partial iliectomy. Histopathology confirmed the diagnosis of aneurysmal bone cyst. Recovery from surgery was uneventful. At re-examination 8 weeks and 8 months postoperatively, the cat was pain free and physical examinations were within normal limits.

Relevance and novel information

Feline aneurysmal bone cysts are rare and reported cases are few. To our knowledge, this is the first report describing the CT appearance of a pelvic aneurysmal bone cyst and partial iliectomy with limb preservation in a cat with successful short-term outcome.

Bone haemophilic pseudotumour of the ulna: A rare complication of haemophilia in a dog

OBJECTIVES

This case report describes for the first time a bone haemophilic pseudotumour in a dog.

CASE DESCRIPTION

A seven-month-old German Shepherd male dog was presented with the complaint of a forelimb weight-bearing lameness with major swelling that expanded dramatically after fine needle aspiration. Radiographs showed a large, well-defined ulnar diaphyseal cystic-like osteolytic lesion. Based on prolonged activated partial thromboplastin time (aPTT) and low factor VIII activity, haemophilia A was diagnosed. Bone scintigraphy, computed tomography, magnetic resonance imaging, and histological findings definitely ruled out malignant neoplasia or inflammation and strongly supported a bone haemophilic pseudotumour over an aneurysmal bone cyst. Segmental ulnar resection  and replacement by a polymethylmethacrylate spacer combined with perioperative bleeding management resulted in a successful outcome.

DISCUSSION

This case provided evidence that a bone haemophilic pseudotumour may be the sole presenting clinical sign of haemophilia A in dogs. Early diagnosis, based on history and magnetic resonance imaging findings, is imperative for prompt treatment leading to successful outcome. It is challenging as fine needle aspiration or biopsy is contraindicated. As described in humans, surgical excision of the lesion combined with management of severe postoperative bleeding was associated with successful outcome in the present case.

CLINICAL SIGNIFICANCE

A bone haemophilic pseudotumour should be considered in the differential diagnosis of expanding mass associated with osteolysis, especially in young male dogs. Perioperative monitoring of the bleeding disorder and subsequent FVIII replacement therapy was of paramount importance in the present case.

Aneurysmal bone cyst secondary to a giant cell tumor of the patella: A case report

The patella is an unusual location for primary and metastatic bone tumors to develop. The most frequently encountered primary osteolytic lesions at the patella include giant cell tumors of the bone (GCT), chondroblastoma and aneurysmal bone cysts (ABC). However, the presentation of an ABC originating secondary to a GCT at the patella is rare. The present study describes such a case in a 46-year-old female. The differential diagnosis of the condition was extensive. The patient underwent curettage and the addition of bone cement to fill the defect. Pathological analysis of the resected tissue demonstrated that the lesion was consistent with an ABC forming secondary to a GCT. A 3-month follow-up was completed subsequent to the surgery, with a computed tomography scan demonstrating no evidence of recurrence. However, frequent and continuous observations of the patient following diagnosis are planned in order to evaluate the long-term efficacy of the surgical treatment. To the best of our knowledge, the present study describes the third reported case in the literature of this rare, double synchronous, benign tumor located at the patella.

Treatment of a unicameral bone cyst in a dog using a customized titanium device

A 4-year-old Shih-Tzu, referred for an enlarged left carpus, was diagnosed with a unicameral bone cyst. A customized titanium device was inserted into cystic lesion and fixed by titanium screws. Sufficient strength of the affected bone with the device inserted to maintain limb function was established after resection of contents of cystic lesion. There was no deterioration of the lesion of bone cyst, and acceptable function of the affected limb with no clinical signs of lameness was maintained during 36 months follow-up. The results of this study demonstrated that bone cyst curettage and use of a customized titanium device could provide an effective alternative treatment of huge lesion of unicameral bone cysts with the intent of preventing pathologic fractures.