Michihito Ishizawa

MRI findings in intramuscular lipomas

Abstract Objective. To investigate the spectrum of magnetic resonance (MR) findings of intramuscular lipoma. Design and patients. A retrospective review of 17 consecutive cases of intramuscular lipoma examined with MR imaging was undertaken. Features assessed included the size and margin of the mass; the homogeneity of the contents, including the presence or absence of intermingled muscle fibers; whether the mass was uninodular or multinodular; and the presence of linear structures between and within the tumor nodules. Three well-differentiated liposarcomas and one dedifferentiated liposarcoma associated with lipoma-like components were also studied to allow a comparison of the benign and malignant lesions. Results. The diameter of the intramuscular lipomas varied from less than 3 cm to more than 10 cm. Ten of the intramuscular lipomas were homogeneous but the remaining seven were inhomogeneous with intermingled muscle fibers within the mass. The intramuscular lipomas were well defined in 12 cases, and infiltrative in five. In one case the margin of the lesion showed prominent infiltration of the surrounding muscle tissue. Of the 17 cases of intramuscular lipoma, 15 were composed of a single nodule, whereas three of four cases of liposarcoma were composed of multinodular masses. Conclusion. The MR findings of intramuscular lipoma varied from a small, single and homogeneous mass identical to ordinary (superficial) lipoma, to a large, inhomogeneous lesion with an infiltrative margin. The presence of infiltrative margins and intermingled muscle fibers in intramuscular lipoma indicates a benign lesion rather than malignancy. In addition, uninodularity of the mass is helpful in differentiating intramuscular lipoma from well-differentiated liposarcoma.

Intra-articular lipoma of the knee joint. A case report.

Although lipomas are common soft-tissue tumors, intra-articular occurrence is unusual1-4. Occasional cases of intra-articular lipoma arborescens have been re ported5-11; however, true intra-articular lipoma is extremely rare3,4. These two entities have been con sidered as one in some recent reports12-14, but true lipoma and lipoma arbores cens are different pathological entities3,4, with different clinical presentation and pathogenesis. Stressing the differences between true lipoma and lipoma arborescens, we describe the case of a patient who had a large intra-articular lipoma and no joint symptoms. A seventy-three-year-old woman who had been previously healthy was admitted to our hospital because of a soft-tissue mass involving the right knee joint. She had first noted the mass ten years earlier, when it appeared to be much smaller. Because she had no pain or limitation of activities, she had not sought medical attention. Upon discovering the mass, the patients local physician referred her to us in September 1999. The medical history and the family history were unremarkable, and the patient remembered no trauma to the knee. Physical examination revealed a soft-tissue mass measuring 6 by 9 cm on the anteromedial aspect of the right knee joint (Fig. 1Fig. 1). On palpation, the mass was found to be adherent to the joint, soft, nontender, and similar in temperature to the surrounding tissue. The mass became more prominent and firm with contraction of the quadriceps muscle. No joint effusion was present. Full extension and 140 degrees of flexion of the knee were possible, without pain or locking. No muscle atrophy was evident. The results of blood tests, including erythrocyte sedimentation rate, rheumatoid factor, and C-reactive protein level, were essentially normal. Fig. 1: Photograph made at the time of presentation, …

Anaplastic large cell Ki-1 lymphoma with bone involvement: report of two cases

Two cases of anaplastic large cell Ki-1 lymphoma involving bone as the most prominent and initial manifestation are reported. The first patient was a 20-year-old male who had back pain and incomplete paraparesis due to vertebral involvement. The second was a 14-year-old girl, whose first clinical signs were fever of unknown origin and sternal bone pain. Radiologically, skeletal lesions were lytic and destructive. Histopathologically, the tumour cells had pleomorphic bizarre nuclei and abundant basophilic cytoplasm. Immunohistochemically, Ki-1 (CD30) reactivity was strongly positive in both cases. Tumour cells were also CD3, CD4, epithelial membrane antigen and interleukin-2 receptor positive in the first case, and CD10, HLA-DR positive in the second case. The former tumour was considered to be of T-cell lineage and the latter of lymphoid progenitor cell origin. Radiation and chemotherapy were temporarily effective. However, both patients died 14 and 7 months after diagnosis, respectively, due to systemic lymph node involvement. These observations suggest that the prognosis for Ki-1 lymphoma involving bone is poorer than indicated in previous reports.

Characterization of a newly established human chondrosarcoma cell line, CS-OKB

Abstract A clonal cell line, CS-OKB, was derived from a human chondrosarcoma and characterized by cytogenetic study, immunocytochemical staining, and reverse transcriptase polymerase chain reaction (RT-PCR). Chromosomal abnormalities characteristic of malignant cartilaginous neoplasms were identified. CS-OKB cells were intensely stained with anti-type II collagen and anti-keratan sulphate antibodies. RT-PCR indicated that CS-OKB transcribes cartilage-specific genes such as type II, X procollagen, and aggrecan. This human chondrosarcoma cell line is stable and expresses well-differentiated chondrocyte-specific genes. It synthesizes well-differentiated chondrocyte-specific molecules in uncoated plastic dishes. CS-OKB may be useful for studies of human chondrocytes and in characterizing human chondrosarcomas.

Partial Rupture of the Quadriceps Tendon (Jumper’s Knee) in a Ten-Year-Old Boy A Case Report

Quadriceps tendon rupture usually occurs in middle-aged to elderly men, especially in those with chronic illness such as renal failure, diabetes mellitus, gout, and hyperparathyroidism. To the best of our knowledge, the youngest patient with this injury described in the literature was a 16-year-old girl who had traumatic rupture of this tendon. It is also known that some athletes suffer jumper’s knee, a disability induced by repetitive microtrauma concentrated at either the superior or inferior pole of the patella. The case presented here is extremely unusual because of the young age of the patient and the abnormal findings mimicking deep-seated hemangioma on MRI and histologic examination. Nevertheless, the macroscopic appearance during surgery showed that the diagnosis was not hemangioma but partial tendon rupture. The dilated veins and intravenous thrombus observed histologically may have arisen as a reaction to the ruptured tendon.

Glomus tumor of the musculotendinous junction of the rotator cuff. A case report.

A rare case of glomus tumor of the rotator cuff is presented. A 35-year-old man had a 20-year history of left shoulder pain. Through physical examination, muscular atrophy in the supraspinatus and infraspinatus muscles and restriction of shoulder motion was seen. Magnetic resonance imaging showed an abnormal oval shadow in the supraspinatus musculotendinous junction, and postcontrast computed tomographic scanning showed a small calcification focus in the tumor. Surgical excision of the tumor and rotator cuff reconstruction using Debeyres procedure were done. Microscopic examination of the tumor showed a typical glomus tumor. It was difficult to diagnose glomus tumor in this patient before surgical intervention. Retrospective consideration indicated that the history of the present illness, computed tomographic scanning, and magnetic resonance imaging were critical for differential diagnosis.

Type-selective muscular degeneration promotes infiltrative growth of intramuscular lipoma

BackgroundIntramuscular lipoma is a relatively common benign neoplasm that is occasionally described as an infiltrating lipoma. Typical benign tumors show a clear margin, however, the infiltrative growth pattern of this lipoma mimics that of a malignant tumor. Although its growth has an effect on muscle bundles and it is known to never metastasize, the mechanism of infiltrative growth is not well understood. Previously, little attention has been paid to pathogenic features of muscle fibers around an intramuscular lipoma.MethodsIn the present study, we focused on pathologic changes of the surrounding skeletal muscles especially to the degenerative features of involving muscular types, and evaluate the role of type-selective muscular degeneration for the infiltrative growth of intramuscular lipomas. Following a review of the medical records in our institute, 17 lesions containing muscle tissues in their specimens (15 infiltrating lipomas, 2 well-circumscribed lipomas) were analyzed immunohistochemically. The tumor from the most recent case was also subjected to ultrastructural analysis. Two cases of the traumatic muscle damage were also evaluated as the control experiments.ResultsThese analyses revealed type-selective muscle involution in 11 of 17 intramuscular lipomas and in 10 of 11 of the infiltrative type, with an involving pattern that resembled that of a neurogenic or myogenic disorder. Immunoreactivity to cathepsin-D, a lysosomal catabolic enzyme, was increased in the involved muscle fibers. Subsarcolemmal vacuoles in the muscle fibers of the peripheral areas were also positive for cathepsin-D, while degenerative findings were not visually apparent in these areas. Ultrastructural analysis revealed degenerative changes in those fibers. Neither positive staining for cathepsin-D nor type-selective atrophy was detected in the sections of traumatic muscle damage.ConclusionsOur findings suggest that type-selective muscular degeneration and endomysial fatty growth as a result of atrophy may modulate the infiltrating growth characteristic of intramuscular lipoma.

Osteosarcoma of the talus : a case report

A 20-year-old man complained of increasing pain and swelling in the right ankle joint. Radiographs of the ankle demonstrated an ill-defined osteolytic lesion in the talus associated with a small, round bone formation just proximal to the neck of that bone. Histologic examination of the lesion showed osteoblastic osteosarcoma originating in the talus. Below-knee amputation was performed because of the peripheral location of the tumor and the close anatomic confines of the foot. A literature review demonstrated that the calcaneus and metatarsals are favorite sites of this tumor in the foot, with only one case in the talus. A second case of osteosarcoma in the talus seems to have not been previously reported.

Foci of signal intensities different from fat in well-differentiated liposarcoma and lipoma: correlation between MR and histological findings

To investigate the histological features of foci, which showed signal intensities different from fat by magnetic resonance (MR) imagings in well-differentiated lipoma-like liposarcomas and a case of lipoma, a retrospective review of these lipomatous tumors was performed to correlate MR and histological findings. Microscopic findings revealed that these foci were also composed of lipomatous tissue. Well-differentiated liposarcoma and benign lipoma associated with such foci should be differentiated from dedifferentiated liposarcoma based on the histological findings.

Parosteal (juxtacortical) chondrosarcoma of the humerus associated with regional lymph node metastasis. A case report.

Recurring parosteal (juxtacortical) chondrosarcoma of the humerus occurred in a 79-year-old man. Roentgenograms of the left humerus showed minimal cortical irregularity and a large soft tissue mass without calcification or periosteal reaction. Magnetic resonance imaging (MRI) showed a multilobular tumor of high intensity (T2-weighted imaging) without marrow involvement. During the left shoulder disarticulation an enlarged axillary lymph nodes was discovered and removed. Macroscopic examination of the disarticulated humerus showed a large yellow parosteal mass, which looked like cartilage, completely surrounding the humeral shaft. The marrow cavity was almost normal except for a small erosion at the site of the olecranon fossa. The histologic diagnosis of the mass was Grade 2 chondrosarcoma of parosteal (juxtacortical or periosteal) origin associated with regional lymph node metastasis. The features that made this case unique were a long history of the tumor (for 32 years), minimal cortical destruction of the bone by the tumor, and regional lymph node metastasis. This case illustrates the differential diagnosis of the parosteal chondrosarcoma from periosteal osteosarcoma and extraskeletal myxoid chondrosarcoma.