Julie Schatz

An unusual variant of intraneural ganglion of the common peroneal nerve

A highly unusual variant of an intraneural ganglion of the common peroneal nerve in a 30-year-old male is presented. There was extrusion of the contents of the cyst into the substance of the nerve, dissecting between the fibres and expanding the nerve in such a way that it mimicked an intraneural tumour clinically, radiologically and histologically. A comprehensive review of the entity is undertaken.

Parachordoma is not distinguishable from axial chordoma using immunohistochemistry

Parachordoma is a rare soft tissue tumor that morphologically resembles chordoma of the axial skeleton but occurs in a peripheral site. A recent study reported immunohistochemical differences between chordoma and parachordoma. While both tumors were positive for cytokeratin (CK) 8/18 (as recognized by the antibody Cam5.2), S100 and epithelial membrane antigen (EMA), only the chordoma was positive for CK7, CK20, CK 1/5/10/14 (as recognized by the antibody 34βE12) and carcinoembryonic antigen (CEA). It has since been suggested that tumors indistinguishable from chordoma that involve the periphery should be termed chordoma periphericum and that these tumors are distinct from parachordoma. In the current study, the clinical, radiological, pathological, immunohistochemical and ultrastructural features of a chordoma‐like tumor involving the deep soft tissues of the lower leg of a 69‐year‐old woman are presented. Microscopically, the tumor had a pseudolobulated growth pattern and consisted of sheets, nests and cords of epithelioid cells, some with a physaliferous appearance, separated by abundant myxoid stroma. The tumor cells were positive for CK 8/18, EMA and S100, showed focal staining for CK7, and were negative for CK20, CK 1/5/10/14 and CEA. On the basis of these results a diagnosis of parachordoma was favored. For comparison, an immunohistochemical analysis of five axial chordomas was also performed. The chordomas showed positivity for CK 8/18 (5 of 5 cases), EMA (5 of 5 cases), S100 (5 of 5 cases), CK 1/5/10/14 (1 of 5 cases) and CK7 (1 of 5 cases). Stains for CK20 and CEA were negative in all five chordomas. The results of the present study suggest that the expression of antigens for CK 1/5/10/14, CK7, CK20 and CEA in chordoma might not be as common as what has been previously reported. The results also suggest that parachordoma might not be easily distinguished immunohistochemically from axial chordoma (and therefore also from so‐called chordoma periphericum).

Epithelioid and spindle cell haemangioma of bone

A case of epithelioid and spindle cell haemangioma of bone occurring in the proximal femur is presented. The tumour had typical microscopic features with a striking lobular pattern comprising spindled and epithelioid areas with admixed inflammatory cells. The case represents only the eighth reported example of this rare tumour, which appears to fit in the spectrum of epithelioid haemangioma. This is the first case to involve the proximal portion of a long bone. A review of the classification and features of similar vascular tumours of bone is presented.

Imaging of tumors in the ankle and foot.

Common bone and soft tissue tumors in the foot and ankle are described in this article, and x-ray and magnetic resonance imaging characteristics are given. Ultrasound can be used for limited indications only, noting that ultrasound features are nonspecific. Of the bone and soft tissue tumors, approximately 7% occur in the foot and ankle. Soft tissue tumors are more common than bone tumors. Tumors of the foot and ankle are generally benign or nonneoplastic. Patients with suspected malignant lesions should be referred to a specialized bone tumor unit before biopsy.

Epiphyseal osteoblastoma-like osteosarcoma

Osteoblastoma-like osteosarcoma is a rare variant of osteosarcoma occurring in this instance in a highly unusual location: the lateral femoral condyle of a 13-year-old girl. The radiological features were non-aggressive and, although slightly unusual, were most suggestive of chondroblastoma.

Case report: periosteal osteosarcoma of the clavicle

Periosteal osteosarcomas are rare and usually affect the meta-diaphyseal region of long bones. We present a case of a periosteal osteosarcoma of the clavicle, a highly unusual site and representing one of only two such cases documented in the English literature. This case illustrates the diagnostic dilemmas in the classification of such tumors, particularly in small biopsy specimens from unusual locations. It emphasizes the importance of radiological and pathological correlation.

Atypical EWSR1 FISH signal patterns in bone and soft tissue tumours:– diagnostic experience with 135 cases

Recurrent Ewing sarcoma breakpoint region 1 (EWSR1) gene rearrangements characterize a select group of bone and soft tissue tumours. In our routine diagnostic practice with fluorescence in‐situ hybridization (FISH), we have occasionally observed EWSR1 gene rearrangements in tumours not associated classically with EWSR1 translocations. This study aimed to review our institutional experience of this phenomenon and also to highlight the occurrence of unusual EWSR1 FISH signals (i.e. 5′ centromeric region or 3′ telomeric region signals) that do not fulfil the published diagnostic criteria for rearrangements.

FISH analysis of selected soft tissue tumors: Diagnostic experience in a tertiary center

Fluorescence in situ hybridization (FISH) is an important ancillary tool for the classification of bone/soft tissue (BST) tumors. The aim of this study was to evaluate the contribution of FISH to the final classification of common BST entities in the molecular pathology department of the Royal Prince Alfred Hospital (RPAH), which is one of the most important referral centers for the management of sarcomas in Australia.