Solitary osteoma of a long bone. A case report

Costal Osteoma: Report of a Case in an Unusual Site

BACKGROUND Osteoma is a benign bone tumor that typically arises in facial bones and less frequently in the long bones. It rarely occurs in the appendiceal skeleton. Pathologic findings are similar to those for parosteal osteosarcoma, periostitis ossificans, and osteoid osteoma. Diagnosing osteoma at an unusual site is always problematic. Here, we present a case of costal osteoma that was found incidentally on screening and produced mild symptoms in the patient. CASE REPORT A 53-year-old man was examined because of a rib mass in the eighth rib on his left side, which had been present for 2 years. A computed tomography scan revealed that the intensely dense mass arose from the external surface of the eighth rib. Microscopic examination showed that the lesion consisted of mature lamellar bone with several Haversian systems, typical of an osteoma. No atypical spindle cells or necrosis were identified. The diagnosis was osteoma. CONCLUSIONS Because the anatomy of the ribs poses a challenge when performing needle biopsy, diagnosing bony lesions solely based on that technique is difficult. The diagnosis of costal osteoma should be made carefully, based on clinical, radiological, and pathological findings. To the best of our knowledge, ours is the first case report about a costal osteoma. It is useful for chest surgeons, pathologists, and radiologists as an example of a rare presentation of this tumor.

Bifocal parosteal osteoma of femur: A case report and review of literature

Osteoma is a benign, slowly growing, asymptomatic, bone-forming tumor arising from cancellous or compact bone. Osteoma usually is a solitary lesion, but in patients with Gardner’s Syndrome it may be multiple. osteoma may rarely have a parosteal localization. Parosteal osteoma has peculiar radiographic, histologic and clinical features. We describe a case report of a 51- years old man with a bifocal parosteal osteoma of the femur in a non-syndromic patient. This is the first described patient with a bifocal lesion. In literature only 24 cases of paraosteal osteoma are found. Our patient underwent surgery and the lesions were fully excised. At one year follow-up there was no evidence of recurrence.

Osteoma of long bone: an expanding spectrum of imaging findings

Osteoma of long bone is an extremely rare, benign bone-forming surface lesion with the largest published case series consisting of only 14 patients. The most important and often most difficult lesion to differentiate from osteoma of long bone radiographically is parosteal osteosarcoma, which is a rare, low-grade surface osteosarcoma with the potential for dedifferentiation. Reports of imaging studies of osteoma of long bone depict a well-defined ossified mass arising from the surface of the diaphysis or metadiaphysis of a long bone. A characteristic feature is the homogeneity of the mass, with uniform density near or equal to that of cortical bone from the base of the lesion to its periphery. The 45-year-old female in this case presented with left hip fullness and was subsequently found to have a proximal femoral osteoma, which was unique in that it contained large fatty marrow spaces that corresponded to bands of relatively low density on plain radiography and computed tomography, giving it a heterogeneous appearance atypical of osteoma of long bone. Furthermore, the osteoma reported here was associated with a small but separate nodular focus of ossification in the adjacent soft tissue. These findings led to a presumptive diagnosis of parosteal osteosarcoma with a local soft tissue metastasis or satellite nodule resulting in radical resection of the tumor. Definitive diagnosis of osteoma was made on histology of both the parent lesion and ossified nodule as no neoplastic spindle cell proliferation was present to establish a diagnosis of low-grade osteosarcoma. This represents, to the best of our knowledge, the first such presentation of osteoma of long bone.

Parosteal osteoma of the clavicle

Introduction. Osteoma is a benign, slowly growing, asymptomatic, osteogenic neoplasm. Osteoma of a bone other than the skull and facial bones is extremely rare. An extremely rare case of parosteal osteoma is reported. Case Presentation. A 51-year-old woman presented with a large mass in the left supraclavicular fossa. Radiographs and computed tomography revealed a well-defined, 9 × 6 cm, lobed mass in the midportion of the clavicle. Magnetic resonance imaging revealed that it had the same density as cortical bone. An open biopsy was performed to rule out malignant bone tumours, and parosteal osteoma was diagnosed. Four years after the biopsy, the patient was asymptomatic. Conclusion. A rare case of parosteal osteoma of the clavicle was described. Open biopsy is required to rule out a malignant bone tumour, even if parosteal osteoma is suspected based on the clinical course and imaging findings.

Juxtacortical osteoma of the ulna

Acase of juxtacortical osteoma of the ulna in a 47-year-old woman is presented. She had a dense bony mass on the ulna. Radiological examinations (plain radiography, computed tomography, magnetic resonance imaging) strongly suggested a rare case of juxtacortical osteoma of a long tubular bone. The differential diagnosis included parosteal osteosarcoma, melorheostosis, osteochondroma, end-stage juxtacortical myositis ossificans, and fibrous dysplasia protuberans. The tumor was excised totally for thorough pathological examination, which revealed it to be composed of lamellar bone, suggesting that the origin was periosteal.

Osteoma of the long bones and the spine. A study of eleven patients and a review of the literature

The clinical features, radiographic and histopathological findings, treatment, and results are described for eleven patients who were managed for an extracranial osteoma at our medical center between 1980 and 1993. Ten of the patients were initially seen because of dull, aching bone pain that had been present for two weeks to thirty years. Radiographs demonstrated single or multiple homogeneous, well defined, radiodense foci with smooth round or lobulated margins. The histopathological features consistently included uniformly dense, compact, cortical-like, mature lamellar bone. The preoperative diagnosis was unclear for all patients, and osteoma was rarely considered in the differential diagnosis. For four patients, a tentative diagnosis of osteosarcoma was made, and a wide excision was carried out in two of these patients. Marginal excision with less than three millimeters of normal tissue around the lesion was performed in most patients. None of the osteomas recurred, and ten patients had relief of the pain. Awareness of the clinical, radiographic, and histopathological features of osteoma, as described, is valuable for making a differential diagnosis and for distinguishing osteomas from other lesions.

Zygomatic osteoma with atypical heterogeneity in a dog

An osteoma of the zygomatic bone in a young dog is described. It had large, centralized radiolucent regions consisting of fatty bone marrow and sparse trabeculae. A discrete, proliferative nodule within the osteoma consisted of closely-packed woven bone trabeculae and pleomorphic osteoblasts associated with haphazard osteoid deposits, resembling osteosarcoma-like change. These heterogeneous structural features were at variance with more classic reports of osteoma, which usually describe a uniform cancellous or cortical bone architecture.

Parosteal osteoma of bones other than of the skull and face

BACKGROUND

Osteoma of the skull and facial bones is not uncommon, is usually asymptomatic, and may be associated with Gardner's syndrome. Osteomas involving other bones are unusual.

METHODS

The authors describe 14 cases (eight men and six women from age 21-66 years) of parosteal osteoma of bones other than of the skull and face.

RESULTS

Thirteen lesions involved long bones, and one involved the clavicle. A long-standing (18 months to 31 years) mass was reported in seven patients. Symptoms of pain, a mass, or both were present in all except three patients who were asymptomatic. Lesions ranged from 2.5 to 20 cm in greatest dimension. Histologically, they blended with the cortex, did not infiltrate the medullary cavity, and consisted of dense sclerotic lamellar bone with haversian systems, similar to the architecture of normal cortical bone. There was no spindle cell proliferation. Nine patients underwent resection, four had biopsy, and one had debulking. With a follow-up of 1-23 years, no recurrence or metastasis was reported.

CONCLUSIONS

Parosteal osteoma must be distinguished from parosteal osteosarcoma, a low grade malignant neoplasm. If radiographs do not identify areas of radiolucency and sections do not contain spindle cells, the diagnosis of parosteal osteoma is justified.