Mutation frequencies of EXT1 and EXT2 in 43 Japanese families with hereditary multiple exostoses.

Hereditary multiple exostoses (EXT) is an autosomal dominant bone disease characterized by the formation of cartilage-capped prominences. EXT is genetically heterogeneous with at least four chromosomal loci. Among the four loci, the exostosis type 1 gene (EXT1) and type 2 gene (EXT2) have been cloned. Previous studies have shown that disease-type-specific frequency of mutations is different among various ethnic populations. To determine those frequencies in the Japanese, we conducted a large-scale mutation screening on both genes. In 23 of 43 Japanese families examined, we found 21 different mutations, of which 18 are novel. Seventeen (40%) of the 23 families had a mutation in EXT1 and six (14%) had a mutation in EXT2, suggesting that the former mutations are more frequent than the latter in Japanese EXT families. Of the 17 families with EXT1 mutations, 13 had those causing premature termination of the EXT1 protein and four showed missense mutations, whereas five of the six families with EXT2 mutations had those causing premature termination and one showed missense mutation. Interestingly, all four EXT1 missense mutations occurred in an arginine residue at codon 340 (R340) that is known as a critical site for expression of heparan sulfate glycosaminoglycans, suggesting that the region encompassing the arginine residue may play an important role in the function of the EXT1 protein. These results expand our knowledge of the ethnic difference of EXT and the structure-function relationship of the EXT genes.

Intraosseous neurilemmoma of the fibula.

We present a case of intraosseous neurilemmoma of the fibula in a 56-year-old woman. The case showed the typical radiographic appearance except for the presence of spotted calcifications that mimicked a cartilaginous tumor. Enhanced MR images revealed the heterogeneity of the tumor, which consisted of Antoni type A and B tissue.

Long-term results of congenital dislocation of the hip treated with the Pavlik harness.

We present the radiographic and clinical results of 158 hips (127 congenital dislocations of the hip, 31 acetabular dysplasias) that were followed-up for > 20 years after the application of the Pavlik harness. The mean Sharp angle of these hips was larger than that of the normal Japanese hip, and the mean center-edge angle was smaller. Thirty hips (19%) were classified as class III, according to Severin's classification. Of 48 unaffected hips in the unilateral cases, 15 hips (31%) had steep acetabula. We believe an intrinsic factor disturbs the normal development of acetabular cartilage in both hips of the patients. Thirty-five hips (22.2%) showed variable grades of deformity of the femoral head, neck, or both. Clinically, most of the treated hips were good in the 3rd decade.

[Radiological and anatomical investigation of calcific tendinitis of the gluteus maximus tendon].

The radiological findings in four cases of gluteus maximus tendinitis were retrospectively analyzed. All the patients underwent radiographic, CT and MRI examinations. Amorphous or round calcifications were detected on lateral radiographs in three cases, and on CT in all cases. A small cortical erosion was observed in three cases on both radiographs and CT. MRI showed a thickened gluteus maximus tendon, but no other specific features. In the supine position, which is common in routine CT and MRI studies, the calcific deposits appeared to be distributed along the vastus lateralis muscle tendon. To correlate these radiographic observations with the topographic anatomy of the tendon's insertion, we investigated 14 thighs of seven cadavers, and clarified that the tendon's insertion was the main component of the lateral femoral intermuscular septum. Consequently we performed MRI on a volunteer in a prone position who was asked to maintain contraction of the gluteus maximus and quadratus femoris muscles. The images obtained showed clearly that the gluteus maximus tendon was directed dorsally. In conclusion, radiography and CT are the modalities of choice for diagnosis of this entity. Additionally, radiologists should be aware that the gluteus maximus tendons are directed laterally as a main part of the lateral femoral intermuscular septum on routine CT and MRI.

MR appearance of periosteal chondrosarcoma of the foot.

OBJECTIVE: To assess the role of MRI in evaluating periosteal chondrosarcoma in the foot, an anatomically complicated location. MATERIALS AND METHODS: Three cases of surgically and histologically confirmed periosteal chondrosarcomas occurring in the foot (58-year-old woman, 57-year-old woman, and 63-year-old man) were retrospectively reviewed with an emphasis on MR findings. RESULTS: Magnetic resonance successfully delineated the hypovascular nature and lobulating pattern of the lesion suggesting the cartilaginous component, the periosteal location with sparing bone marrow, and the extent of involvement of adjacent structures. These findings were either not seen or less clearly seen on CT in the former two cases. CONCLUSION: In cases of periosteal chondrosarcomas in the foot MRI can play a significant role both in the characterization of the lesion and in planning surgical therapy.

[MR imaging of fatigue fractures: characteristics and value for differential diagnosis].

The magnetic resonance (MR) appearance of five fatigue fractures was analyzed in an attempt to isolate characteristic MR findings which would facilitate the differentiation of this entity from bone neoplasms and osteomyelitis. The bone lesions reviewed for comparison included three osteoid osteomas, eight osteosarcomas, two malignant lymphomas and four osteomyelitis. Four characteristics useful for differentiation were found: 1) All fatigue fractures showed a smooth and continuous periosteal reaction with a superficial layer of high signal intensity on T 2-weighted images, while all malignant bone tumors and osteomyelitis showed irregular, interrupted or undetectable periosteal reaction, and osteoid osteomas showed no superficial high signal on periosteal reactions. 2) In all fatigue fractures and osteoid osteomas, abnormal signals in the bone marrow were ill defined, whereas they were well defined in all bone neoplasms and one of four osteomyelitis. 3) None of the fatigue fractures or osteoid osteomas was associated with extraosseous components. 4) Fatigue fractures showed little signal change in the surrounding soft tissues, while most of the bone tumors and osteomyelitis were accompanied by high signal in the adjacent soft tissues on T 2-weighted images. These MR characteristics are helpful in differentiating fatigue fracture from bone neoplasms and osteomyelitis, enabling unnecessary surgical procedures to be avoided.

Results of congenital dislocation of the hip joint with open reduction followed up to an age of fifteen years or more.

Forty-three hips (35 patients) with congenital dislocation with open reduction were reviewed. They were under 7 years old at the time of open reduction and over 15 years old at the follow-up. According to Severin's classification, 11 hips were classified as Group I, 7 hips as Group II, and 20 hips as Group III. Avascular necrosis was observed in 20 hips, but no Kalamchi's groups III and IV. The findings were that the younger the patient's age at open reduction, the higher the incidence of avascular necrosis. The cases in which the cartilaginous acetabular floor was demonstrated to be thicker in preoperative arthrography tended to yield unsatisfactory results.

MR of enchondroma and chondrosarcoma: rings and arcs of Gd-DTPA enhancement.

MR studies of five chondrosarcomas and three enchondromas were performed with intravenous Gd-DTPA administration. All tumors showed enhancement of scalloped margins and curvilinear septa (ring-and-arc pattern) on T1-weighted SE sequences with Gd-DTPA. On radiologic-pathologic correlation, the enhanced areas corresponded to fibrovascular bundles surrounding hyaline cartilage lobules. The rings and arcs of enhancement with Gd-DTPA on MR is a reflection of the lobulated growth pattern of cartilaginous tumors and therefore helpful in differential diagnosis of bone tumors.

Giant cell tumors of bone containing large amounts of hemosiderin: MR-pathologic correlation.

We present three giant cell tumors of bone that contained large amounts of hemosiderin and compare their MR appearance with intraoperative findings and histological characterization. Histologically, hemosiderin was found in multinucleated giant cells, mononuclear stromal cells, and xanthoma cells. All cases showed markedly decreased signal areas on both T1- and T2-weighted MR imaging due to hemosiderin deposition; this made evaluation of the integrity of the adjacent cortices difficult. In one case, extraosseous tumor extension appeared as a signal void area on MR imaging. Findings on immunohistochemical studies suggested the giant cells may have a histiocytic nature. Because the tumor cells themselves have a phagocytic nature, the decreased signal areas in and around giant cell tumors should be regarded as active tumor tissues in delineating the tumor on MR imaging.

[Periosteal osteosarcoma of the femur: a pathological and ultrastructural study].

A femoral, diaphyseal tumor was found in a 17-year old male, and the diagnosis of periosteal osteosarcoma was made, based on the typical radiological and pathological findings. Microscopic observation on a resected specimen revealed that the tumor was covered with the intact periosteal fibrous layer and did not extend beyond the periosteum. The adjacent cortex was free of tumor. These findings indicated that the tumor originated from the periosteal cambium layer, which lies between the periosteal fibrous layer and the cortex. For transmission electron microscopic examination, the tissue was obtained at open biopsy. Ultrastructurally, no specific cell of periosteal osteosarcoma was found. Although most types of osteosarcoma cells were identified in the tumor (osteoblast-like, chondroblast-like, fibroblast-like, primitive mesenchymal-like, osteoclast-like and so on), the ultrastructural characteristics were of wide variety and of low malignancy.

[A case of chondrosarcoma arising from the left first rib].

A 46-year-old female was admitted to our hospital because of a left supraclavicular tumor. The chest CT scan and MR imaging revealed that the tumor arose from the left first rib and developed into the supraclavicular region. In this case, we tried to resect the tumor using the so-called "trap-door" thoracotomy. Although removal of subclavian vessels and brachial plexus from the tumor was easily performed, we could not enough treat the vertebral side of the first rib through this thoracotomy without the T1 nerves injury. In cases of superior sulcus tumors developing into the posterior chest wall, a posterior incision combined with an anterior one will be useful to remove these tumors safely.

Vimentin-positive squamous cell carcinoma arising in a burn scar. A highly malignant neoplasm composed of acantholytic round keratinocytes.

Two patients had unusual squamous cell carcinoma (SCC) arising in a burn scar. The SCCs rapidly recurred and metastasized after radical operation, and the patients died of disseminated metastases. Histopathologically, the SCC was poorly differentiated and consisted of acantholytic round cells that diffusely proliferated into the deep dermis. However, small, solid nests composed of squamoid cells were focally observed. Immunohistochemical studies revealed that the acantholytic round neoplastic cells expressed not only keratin but also vimentin, and the coexpression was substantiated with double immunostaining. Vimentin-positive SCC composed of acantholytic round neoplastic cells may be a highly malignant subset of cutaneous SCC.

Developmental changes of carbonic anhydrase activity of parotid gland and stomach of goat.

1. Carbonic anhydrase activities in the various tissues of ruminants and non-ruminants were compared. 2. The highest activity was found in the parotid gland of ruminants such as bovine and goat. However the activity in the kidney was not significantly different between the ruminants and non-ruminants. #. The effect of development on the carbonic anhydrase activity was studied. The activities in both the parotid gland and kidney of the goat were found to increase with age whereas the activities of the pancreas, liver and submaxillary gland did not change significantly. 4. The activities in the abomasum of the goat also increased with age however the other stomachs did not vary prominently.