A rare case of periosteal osteoblastoma located in the frontal cranial bone

Periosteal osteoblastoma is an extremely rare bone-forming neoplasm located on the surface of cortical bone. Of the fewer than 30 cases of periosteal osteoblastomas found in the literature, 2 have been reported to be located in cranial bone, and these have not been documented in detail with clinical history, radiographic findings, macroscopic features, and microscopic findings. Although the differential diagnoses of periosteal lesions include parosteal and periosteal osteosarcoma, periosteal chondroma and chondrosarcoma, osteochondroma, osteoid osteoma, periostitis ossificans, and myositis ossificans, an important differential diagnosis both radiologically and pathologically of such a lesion in the cranium is meningioma. We report an unusual case of periosteal osteoblastoma located in the frontal cranial bone that was radiologically consistent with a meningioma. The differential diagnosis of metaplastic meningioma with differentiation toward bone is discussed.     

Periosteal osteoblastoma: a case report and a review of the literature

Osteoblastomas located on the surface of cortical bone, so-called periosteal (juxtacortical) osteoblastomas, are extremely rare. A 24-year-old man complained of pain and swelling in the left knee. The clinical and radiological investigation showed a tumor located in the posterior portion of the distal shaft of the femur. The radiological differential diagnosis included parosteal osteosarcoma, periosteal chondroma and periostitis ossificans. A frozen section was obtained and histology revealed an osteoblastoma with large epithelioid-appearing osteoblasts consistent with an aggressive osteoblastoma. An en bloc resection of the tumor was performed and the definitive histology of the whole specimen revealed a typical osteoblastoma. The authors draw attention to the fact that periosteal osteoblastoma is a rare tumor that could be mistaken clinically and histologically for other and more common tumors at this location.     

Chondroblastoma-like chondroma of soft tissue: report of the first case in the base of skull

Chondroblastoma-like chondroma (CLC) of soft tissue is a rare benign neoplasm that usually involves the soft tissues of the hand. This report describes the first case of CLC of soft tissue arising in the base of the skull. A 33-year-old man was seen with a slow growing mass in the right parotid region of his face. The noncontrast computed tomographic scans showed an 8.5-cm mass with calcifications involving the right masticator space and extending through the bone into the middle cranial fossa. The radiologic differential diagnosis included osteosarcoma, leiomyosarcoma, chondrosarcoma, and giant cell tumor. During surgery, the large lateral skull base tumor appeared to involve the middle and infratemporal fossae and eroded the surrounding bone. Although the tumor was removed piecemeal, total excision was performed. On microscopic examination, the tumor displayed lobules of mature hyaline cartilage with numerous chondroblasts, coarse calcifications including chicken wire calcifications, and scattered osteoclasts. No atypia, mitoses, necrosis, or osteoid formation was seen. The tumor was diagnosed as chondroma with chondroblastoma features of the soft tissue. His postoperative clinical course was uneventful; however, after 7 months, he had a local recurrence identified on follow-up magnetic resonance imaging. He underwent repeat surgical excision of the tumor, which showed similar histology as the previous excision. This large skull based tumor eroding the bone, which clinically and radiologically mimicked a malignant process, was an unusual presentation of a benign cartilaginous neoplasm. Pathologists should be aware that CLC may occur in the base of the skull and this lesion should be differentiated from the other benign or malignant tumors arising in this area. These lesions have a potential for local recurrence; hence, a close follow-up is recommended.     

Desmoplastic fibroma of bone with extensive cartilaginous metaplasia

Desmoplastic fibroma of bone is a rare tumor demonstrating the same histologic and biologic features of its soft tissue counterpart, aggressive fibromatosis. We report the second case of desmoplastic fibroma of bone with extensive chondroid metaplasia. The tumor arose in the left ischium of a 51-year-old male, with extension into adjacent musculature as a pseudoencapsulated mass. The infiltrating growth and quality of the fibrous component are characteristic of desmoplastic fibroma, and in addition, abrupt transitions into bland hyalin cartilage were frequent. Discriminating features of this lesion from other bone tumors capable of biphasic expression of fibrous and chondroid elements are discussed.     

Soft tissue osteochondroma: case report and immunohistochemistry for parathyroid hormone-related protein

Surface lesions of bone usually present little diagnostic dilemma because the majority are conventional osteochondromas. Other surface bone lesions include periosteal chondroma, periosteal chondrosarcoma, and parosteal osteosarcoma. Mineralized soft tissue lesions such as myositis ossificans, synovial chondroma, and synovial sarcoma may present in a similar fashion when they occur in a juxtaarticular position. The soft tissue osteochondroma or paraarticular osteochondroma may simulate some of these more aggressive tumors, and its recognition is important to avoid overtreatment. A case of an 11-year-old male with a soft tissue osteochondroma is reported to illustrate the characteristic radiographic and histological features of this rare entity. No prior reports have examined soft tissue osteochondroma for expression of parathyroid hormone related protein, an established cartilage tumor proliferative mitogen.     

Extraskeletal chondroma of the fallopian tube

Extraskeletal chondroma can occur in the hands, feet, head and neck. This tumor usually presents as a small solitary nodule. The histogenesis of the tumor is controversial, but some have suggested a metaplastic origin. Chondroma of the fallopian tube is very rare. There is only one report in English literature. The origin of this tumor can be subcoelomic mesenchyme of the tubal serosa or mesenchyme of the myosalpinx. We describe a case of chondroma arising from the serosal surface of the fallopian tube with a review of literature. A 30-yr-old woman visited hospital due to left adnexal mass. On operating finding, 2 x 3 cm sized nodular mass was noted on the left tubal serosal area. The excised mass showed multilobulated appearance covered with thin fibrous membrane. The cut surface was solid, grayish yellow, and myxoid with a focal gelatinous area. The microscopic finding showed islands and elongated lobules of mature benign cartilage without cytologic atypia.     

Mesenchymal hamartoma of the chest wall in an infant

Mesenchymal hamartoma of the chest wall is a very rare, benign tumour with distinct clinical, radiological and histopathologic characteristics. The lesion develops during foetal life, and is present at or shortly after birth with an extrapleural mass arising from the rib cage with or without respiratory distress and marked rib deformity. Several imaging techniques have been used for diagnosis, but a definitive diagnosis is established only by histopathological examination. Such lesions are composed of a varying admixture of hyaline cartilage that has features resembling growth plate cartilage, along with fascicles of spindle cells, woven bone and hemorrhagic cysts. Accurate diagnosis of mesenchymal hamartoma is important since many chest wall masses in children are malignant. We report a case of mesenchymal hamartoma of the left posterior chest wall surgically resected in an infant who was found to have a palpable mass at birth. Two years after surgery, the patient is alive and well, with no evidence of recurrence.     

Unusual autopsy finding in a case of metastatic teratocarcinoma

An unusual autopsy finding was seen in a young case of metastatic teratocarcinoma of the right testis. The patient presented with features of myocardial ischemia and died of sudden cardiac arrest. At autopsy, the lungs were studded with variably sized metastatic nodules composed of glistening hyaline cartilage. Examination of the coronary arteries revealed complete occlusion of the left anterior descending and left circumflex artery lumina by tumor emboli composed of glistening white chondromyxoid material. Histopathology confirmed the presence of mature hyaline cartilage and chondromyxoid material in tumor emboli. The individual died due to severe coronary insufficiency and sudden cardiac arrest secondary to complete luminal occlusion of the left anterior descending and left circumflex artery lumina by tumor emboli composed of hyaline cartilage.     

Benign cartilage tumors

Benign cartilage lesions can be divided into those that differentiate towards fetal type cartilage (chondroblastoma and chondromyxoid fibroma) and those that differentiate towards mature hyaline type cartilage (osteochondroma, chondroma). Nora lesion is a reactive periostitis that mimics osteochondroma and is discussed with this group of lesions. This article reviews their clinical, radiological and pathological features along with the main differential diagnoses. It also briefly reviews multiple osteochondromas, multiple enchondromas and Maffucci syndrome.     

Chondromas (enchondroma, periosteal chondroma, enchondromatosis)

Chondromas combine a group of benign cartilaginous tissue tumors with common histological manifestations. The tumors (enchondroma, periosteal chondroma, and enchondromatosis) differ in sites and clinical manifestations. Chondromas are generally hypocellular, avascular tumors with an abundance of hyaline cartilage matrix and chondrocytes located diffusely, in clones or lobules. Small bone chondromas, Ollier's disease, and Mafucci's syndrome are characterized by the tumor tissue containing a large number of cells and by greater cytological atypia. Enchondroma is successfully treated by surgical methods.     

Chondromyxoid fibroma of the femur: a case report with intra-cortical location.

Chondromyxoid fibroma (CMF) is the least common benign cartilaginous tumor, comprising less than 0.5 to 1% of all skeletal neoplasms. This subject was a 16-year-old female with a three-year history of pain involving the distal femoral metaphysis. This case showed an unusual feature: it was intracortical in location. Radiologic differential diagnosis included metaphyseal fibrous defect, periosteal chondroma, simple or aneurysmal bone cyst, and cortical abscess. On operation, the lesion filled the intracortical defect with whitish myxoid soft tissue, bulging into the adjacent soft tissue. Microscopically, it showed typical features of chondromyxoid fibroma composed of mainly myxoid nodules and peripheral fibrous elements with focal chondroid differentiation.     

Tenosynovial chondroma of the hand: A case report with a brief review of the literature

Tumors of hyaline cartilage occurring in the soft tissues of the hands and feet arise by metaplasia from the synovium of tendon sheaths and have a benign clinical evolution. Although recurrences may develop, they show no tendency to metastasize. The majority of these tumors prove to be diagnostic difficulties because of the alarming histologic atypia they display. We report a case of tenosynovial chondroma of the hand and briefly review the salient features of these lesions.     

Periosteal osteoblastoma of the calvaria mimicking a meningioma

While osteoblastoma of the cranial vault is rare, the periosteal form of the tumor is highly unusual, with only one case reported in the English literature. We report on a 24-year-old woman presenting with headache and tinnitus. Magnetic resonance imaging of the brain showed an extra-axial temporal mass with findings that were suggestive of a meningioma. The mass was excised completely, and histological examination revealed a periosteal osteoblastoma arising from the inner surface of the temporal bone and adhering to the dura. The tumor was strongly positive for epithelial membrane antigen, a feature not previously described in osteoblastoma, and one that could lead to a mistaken diagnosis of metaplastic meningioma in a limited sample. A detailed literature review of 40 other reported cases of calvarial osteoblastoma is presented. Apart from being slightly more common in females, calvarial osteoblastoma is similar in all other respects to that arising at conventional skeletal sites. Accurate histological diagnosis of a calvarial osteoblastoma requires adequate sampling of the tumor, including its interface with adjacent structures. Correlation with the radiological findings is crucial for the diagnosis in most cases; however, it is not helpful in differentiating the rare intracranial periosteal variant from a meningioma.     

Osseous metaplasia in renal cell carcinoma: report of a rare case

Focal calcifications are frequently seen in renal masses including renal cell carcinoma (RCC). Osseous metaplasia, on the other hand, is a rare finding in RCC. We report a case of RCC with radiological evidence of speckled calcification that showed osseous metaplasia on histopathological examination. The clinical and pathologic differential diagnosis for this tumor is discussed along with a review of the literature on this unusual phenomenon.     

Periosteal osteosarcoma of the femur with bone marrow involvement: A case report

Periosteal osteosarcoma is an exceedingly rare type of chondroblastic osteosarcoma, showing rather better prognosis, and secondary bone marrow involvement is unusual. A case of a 22 year old male with periosteal osteosarcoma of the right femur with an associated bone marrow lesion is presented. The juxtacortical tumor, 16 ×11 × 9 cm, was located on the bone cortex of the upper diaphysis and extended into the surrounding soft tissues. A minimal bone marrow lesion was present, although the bone cortex was quite intact. Microscopically, the tumor consisted exclusively of atypical chondroblastic cells with a small osteoblastic area. The bone marrow lesion, interestingly, contained both multiple nodules of well-differentiated chondrosarcomatous components and a few demarcated foci of atypical spindle cells producing a fine osteoid matrix. It was reasonable to conclude, therefore, that this tumor was a periosteal osteosarcoma with an unusual secondary bone marrow lesion rather than a conventional (central) chondroblastic osteosarcoma with soft tissue invasion. The patients good prognosis with no tumor recurrence or metastasis during more than 7 years follow-up after surgery supports this conclusion.     

Parachordoma of the gastric serosa: report of a myxoid mimicry in an unusual location

The authors report a case of an incidentally discovered myxoid stromal tumor occurring in the outer wall of the stomach of a 65-year-old woman. The tumor was phenotypically consistent with parachordoma (or myoepithelioma), showing a chordoid microscopic appearance of tumor cells loosely arranged within a myxoid or hyaline background. Immunoreactivity for high-molecular-weight keratins, S100 protein, and vimentin was detected. In this report, the authors address the differential diagnosis of parachordoma and the unusual location of this neoplasm.     

Ovarian signet-ring stromal tumor: a potential diagnostic pitfall

Signet-ring stromal tumor is a rare ovarian neoplasm with only 10 reported cases in the literature. We report an unusual case of ovarian signet-ring stromal tumor in a 69-year-old woman who presented with right adnexal mass and underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. The diagnosis was based on histological, histochemical, immunohistochemical, and electron microscopy characteristics. The main significance is to differentiate this benign tumor from the highly malignant Krukenberg tumor, and this differential diagnosis is discussed.     

Soft tissue chondroma—a study of 15 tumours

Fifteen cases of soft tissue chondroma have been reviewed. This lesion shows an equal sex incidence and occurs predominantly in middle-aged individuals. The majority arise in the hands and feet. Histologically these tumours are largely composed of adult-type hyaline cartilage, but in all cases foci show nuclear atypia and pleomorphism. In cartilaginous lesions of the axial skeleton or large limb bones this would probably have led to a diagnosis of well differentiated chondrosarcoma. Despite these worrying features none of the seven cases for which follow-up information is available recurred. The importance of recognizing the benign nature of these little-known tumours is stressed. The differential diagnosis of soft tissue cartilaginous tumours is briefly discussed.     

Atypical chondroma of the cricoid cartilage: fine-needle aspiration cytologic and histopathologic findings

Chondroma of the laryngeal skeleton is a rare, benign neoplasm manifested either as a neck mass or, if situated within the airway, as slowly progressive obstruction, hoarseness, or dyspnea. The most common site is the posterior plate of the cricoid cartilage. An atypical perichondrial chondroma arising from the anterior plate of the cricoid cartilage membrane as a neck mass in a young female is presented. The diagnosis was made on a fine-needle aspiration of the mass and subsequently confirmed by histologic examination of the excised mass. Although rare, cartilaginous tumors of the laryngeal skeleton can manifest as a neck mass, and the diagnosis can be made by fine-needle aspiration biopsy in combination with radiographic and clinical examinations. Therefore, the existence and inclusion of these tumors in the differential diagnosis of neck masses by aspiration biopsy should be considered by clinicians and pathologists, and especially cytopathologists, when cartilaginous components are encountered.