Multilobular tumour of the caudal cranium causing severe cerebral and cerebellar compression in a dog

Multilobular osteochondrosarcoma of the vertical ramus of the mandible in a cat

A 7-year-old castrated male domestic shorthair cat presented with locked jaw syndrome and firm swelling in the right temporal region of the skull. A computed tomography (CT) scan showed a heavily calcified mass of the right coronoid process of the mandible with a popcorn appearance, consistent with a multilobular osteochondrosarcoma. The zygomatic arch was displaced laterally and ventrally due to the mass effect. The temporomandibular joint was not involved. Surgical treatment was performed and consisted of the removal of the zygomatic arch and the vertical ramus of the mandible. It was possible to open the mouth normally immediately after surgery. Recovery was uneventful. Histological examination of the mass confirmed multilobular osteochondrosarcoma. This type of tumor is rarely encountered in dogs, and a literature search reveals only two cases in cats: one arising from the skull and one from thoracic wall. This case report documents the first description of a multilobular osteochondrosarcoma of the mandible in a cat.

Multilobular tumor of bone on the forehead of a guinea pig

Multilobular tumor of bone (MLTB) is an infrequent, slow-growing, bone neoplasm formed predominantly on the head. These tumors can behave as malignant neoplasms clinically and pathologically and can metastasize occasionally. No cases of MLTB in rodents have been reported, to our knowledge. We describe a novel case of an MLTB in a guinea pig. An adult guinea pig had an exophytic mass fixed on the frontal bone, maxilla, and nasal bone. On radiography, the mass had a spherical contour and variable density and was formed on the surface of the cranial bones. The mass was excised surgically. The cut surface was light-yellow to milky-white and had a granular texture with fine fibrous septa. Histologically, the neoplasm had a multilobular pattern, which consisted of many islands of bone and/or cartilage matrix surrounded by small cells and separated by fibrous septa, which closely resembles the equivalent neoplasm in dogs.

Multilobular tumor of the zygomatic bone in a dog

Multilobular tumor of bone (MTB) (also known as Multilobular Osteochondrosarcoma) is an uncommon bone tumor frequently located on the skull of dogs, rarely on the ribs or pelvis. These neoplasms are slow growing, locally invasive, and have the potential to compress and invade the brain. A 10-year-old mixed breed dog was presented with a history of approximately 4 months of progressive growth of a left zygomatic mass. Radiographic investigation revealed a finely granular or stippled non homogeneous radiopaque mass involving the zygomatic arch. After surgery, grossly the neoplasm consisted of multiple, variably sized, grayish-white to yellow nodules separated by collagenous septa of different thickness. Histologically, the tumor was characterized by the presence of multiple lobules containing osteoid and cartilage, separated by a net of fibrous septae. This neoplastic pattern was consistent with a typical multilobular tumor of bone and based on clinical, radiographical, gross and light microscopic findings the definitive diagnosis was made. While reviewing veterinary literature only few cases of MTB were found in dogs.