Calcific tendinitis of the gluteus maximus tendon: CT findings

Two cases of calcific tendinitis of gluteus maximus muscle are presented. The CT findings, including amorphous calcification without soft tissue mass and possible cortical erosion at the femoral enthesis of the gluteus maximus muscle, are highly suggestive of calcific tendinitis at this unusual but classical location. Ossifying entheses with well-defined cortical defect are frequent at the femoral insertion of the gluteus maximus muscle in asymptomatic subjects and must be differentiated from a real cortical erosion sometimes associated with these calcific tendinitis. Received: 16 July 1998; Revision received: 14 September 1998; Accepted: 13 October 1998     

Non-communicating intramuscular ganglia

Intramuscular ganglia are rare. Most of the previously reported cases were connected with an adjacent joint. We present the imaging findings in three patients who had intramuscular ganglia that were not connected with a joint. Magnetic resonance showed a septated, encapsulated mass that was iso- or hypointense to muscle on T1-weighted and hyperintense on T2-weighted images. A post-contrast T1-weighted scan in one patient showed minimal capsular enhancement. Ultrasound performed in one case showed an encapsulated, anechoic mass. Received 9 June 1997; Revision received 9 January 1998; Accepted 11 March 1998     

De novo malignant transformation of giant cell tumor of bone

Two cases of malignant lesions are reported, both of which arose secondary to an originally benign giant cell tumor (GCT) of bone. The first case was a typical benign GCT, which occurred in the left proximal tibia of a 31-year-old woman. The tumor was treated by curettage and bone grafting. However, it recurred twice during 15 years of follow-up. The second recurrence showed that the lesion histologically had turned into malignant fibrous histiocytoma. The second case also started as an initially benign GCT that arose in the left distal femur of a 41-year-old man. The patient underwent curettage and bone grafting. The lesion recurred 13 years postoperatively. The histological appearance of the recurrent tumor showed it to be an osteogenic sarcoma. In both patients, radiation had never been given. Malignant transformation has rarely been reported in patients with GCT of bone who have not received radiation treatment. Received: 12 June 2000 Revision requested: 17 August 2000 Revision received: 13 October 2000 Accepted: 18 October 2000     

Solitary infantile myofibromatosis involving the clavicle

A rare case of solitary infantile myofibromatosis of bone is reported in the right clavicle of a 15-year-old boy. A radiograph demonstrated an osteolytic lesion with a sharp margin and a sclerotic rim. CT revealed a circumscribed lesion with slight expansion of the cortex. On MRI the lesion appeared isointense to muscle on T1-weighted images, bright on T2-weighted images, and showed marked gadolinium enhancement. The patient was well, without evidence of recurrence or metastasis, 4 years and 5 months following resection. Received: 11 August 1998 Revision requested: 5 October 1998, 18 March 1999 Revision received: 15 March 1999, 23 April 1999 Accepted: 28 April 1999     

MRI findings in intramuscular lipomas

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. Received: 26 May 1998 Revision requested: 7 August 1998 Revision received: 10 November 1998 Accepted: 16 November 1998     

Pseudomyxoma retroperitonei

We report a rare case of pseudomyxoma retroperitonei in a 58-year-old woman with a past history of severe appendicitis. The imaging showed a multicystic mass similar to pseudomyxoma peritonei, but the tumor was located in the retroperitoneal space. Received: 20 October 1997; Revision received: 10 February 1998; Accepted: 2 March 1998     

MRI appearance of clear cell hidradenoma

We present the first reported MR imaging findings of a histologically proven clear cell hidradenoma. A fluid level was noted on all pulse sequences in this lesion, which demonstrated a prominent hemorrhagic component on sectioning. The presence of an enhancing nodule was also noted, differentiating this lesion from a post-traumatic hematoma. Fluid levels in a well-defined subcutaneous soft tissue mass should suggest the possibility of a hidradenoma. Received: 19 June 1998; Revision requested: 29 July 1998; Revision received: 28 October 1998; Accepted: 29 October 1998     

Subcutaneous granuloma annulare: MR imaging and literature review

Subcutaneous granuloma annulare (SGA) is little known to radiologists. Better knowledge of this lesion may prompt accurate diagnosis. A typical case is presented with plain radiography, ultrasound and MR imaging, and is confirmed by histology. When an otherwise healthy child presents with a rapidly growing, solitary, nontender, subcutaneous soft tissue mass, located on the scalp or extensor aspect of the limbs, that radiologically presents as an indistinct radiodense and hypoechoic mass, isointense to muscle on T1- and slightly hypointense to fat on T2-weighted MR images, without calcifications, bone involvement or extracompartmental invasion, SGA should be suspected. Received 5 June 1997; Revision received 29 October 1997; Accepted 8 January 1998     

Multifocal bone tuberculosis presenting as a breast mass: CT and MRI findings

Chest wall involvement is an uncommon manifestation of musculoskeletal tuberculosis. We present computed tomography and magnetic resonance imaging findings in a case with multifocal musculoskeletal tuberculosis presenting as a breast mass. These radiological modalities are not diagnostic without histopathological confirmation, but they are valuable guides to surgery in defining the extent of disease involvement. Received: 1 July 1998; Revision received: 8 October 1998; Accepted: 12 October 1998     

Extra-abdominal desmoid mimicking malignant male breast tumor

A rare case of extra-abdominal desmoid tumor is reported. A palpable mass was detected in the right breast of a 47-year-old man. Mammography showed a stellate mass without calcification, and breast ultrasound examination revealed a solid, inhomogeneous, non-calcified lesion. The result of cytological examination of the fine-needle aspiration biopsy specimen was equivocal. Histology of the surgical specimen showed extra-abdominal desmoid tumor. Extra-abdominal presentation of this semimalignant tumor is rare and may mimic malignant breast tumor. Differential diagnosis is difficult and usually based on the result of the histological examination. Received: 2 July 1998; Revision received: 8 September 1998; Accepted: 14 October 1998     

Intra-articular gouty tophi of the knee: CT and MR imaging in 12 patients

Objective. To define the imaging characteristics of intra-articular tophi of the knee. Design and patients. Twelve patients with intra-articular tophi in the knee were studied with routine MR imaging, gadolinium (Gd)-enhanced MR imaging, and CT over a 4-year period. There were 11 men and one woman, 25–82 years of age (mean age 48 years). Four patients did not have a documented history of gout at the time of the MR examination. The diagnosis of intra-articular tophi was provided by arthroscopy and histological examination (5 patients), by microscopic study of joint fluid (5 patients), or by characteristic clinical, laboratory and imaging findings (2 patients). Results. In 15 MR examinations the tophi were located purely intra-articularly in 10 knees. In the remaining five MR studies, periarticular soft tissues or bone, or both, were involved. All the intra-articular tophi manifested low to intermediate signal intensity on both T1- and T2-weighted images. All five Gd-enhanced MR examinations demonstrated a heterogeneous peripheral enhancement. All 10 CT scans showed varying degrees of stippled calcifications within the tophi. The nature of the calcifications was confirmed on histological examination in three patients. Conclusion. Presenting clinical manifestations of gout may relate to intra-articular tophaceous deposits. Such deposits present as masses on MR images with low to intermediate signal intensity on both T1- and T2-weighted images and a characteristic enhancement pattern following intravenous Gd administration. These features relate primarily to internal calcifications, which are most evident on CT images. MR evaluation (including Gd administration) supplemented, in some cases, with CT scanning allows accurate diagnosis of intra-articular tophaceous deposits. Received: 24 August 1998; Revision requested: 1 October 1998; Revision received: 19 October 1998; Accepted: 23 October 1998     

Deep soft tissue leiomyoma of the thigh

A case of ossified leiomyoma of the deep soft tissues of the left thigh is presented. The radiographic appearance suggested a low-grade chondrosarcoma. MRI of the lesion showed signal characteristics similar to muscle on both T1- and T2-weighted spin echo sequences with linear areas of high signal intensity on T1-weighted images consistent with medullary fat in metaplastic bone. Histopathological examination of the resected specimen revealed a benign ossified soft tissue leiomyoma. Received: 23 December 1998 Revision requested: 31 January 1999 Revision received: 11 March 1999 Accepted: 16 March 1999     

Primary leiomyoma of the ovary: a case report

The imaging features of primary ovarian leiomyoma have seldom been described because of the very low prevalence of the tumor. Herein we present a case report on its magnetic resonance imaging features. Both T1- and T2-weighted images revealed a low-signal-intensity mass, which was well circumscribed and sharply demarcated from the uterus. Magnetic resonance imaging was useful in distinguishing it from a malignant ovarian tumor and uterine leiomyoma. Received 10 October 1997; Revision received 2 February 1998; Accepted 4 February 1998     

MR imaging of clear cell sarcoma (malignant melanoma of the soft parts): a multicenter correlative MRI-pathology study of 21 cases and literature review

Objective. To evaluate MR imaging and pathology findings in order to define the characteristic features of clear cell sarcoma of the soft tissues (malignant melanoma of the soft parts). Design and patients. MR examinations of 21 patients with histologically proven clear cell sarcoma of the musculoskeletal system were retrospectively reviewed and assessed for shape, homogeneity, delineation, signal intensities on T1- and T2-weighted images, contrast enhancement, relationship with adjacent fascia or tendon, secondary bone involvement, and intratumoral necrosis. In 19 cases the pathology findings were available for review and for a comparative MR-pathology study. Results. On T1-weighted images, lesions were isointense (n=3), hypointense (n=7) or slightly hyperintense to muscle (n=11). Immunohistochemical examination was performed in 17 patients. All 17 specimens showed positivity for HMB-45 antibody. In nine of 11 lesions with slightly increased signal intensity on T1-weighted images, a correlative MR imaging-pathology study was possible. All nine were positive to HMB-45 antibody. Conclusions. Clear cell sarcoma of the musculoskeletal system often has a benign-looking appearance on MR images. In up to 52% of patients, this lesion with melanocytic differentiation has slightly increased signal intensity on T1-weighted images compared with muscle. As the presence of this relative higher signal intensity on T1-weighted images is rather specific for tumors displaying melanocytic differentiation, radiologists should familiarize themselves with this rare entity and include it in their differential diagnosis when confronted with a well-defined, homogeneous, strongly enhancing mass with slightly higher signal intensity compared with muscle on native T1-weighted images. Received: 18 October 1999 Revision requested: 19 November 1999 Revision received: 21 January 2000 Accepted: 25 January 2000     

Marginal erosive discovertebral ”Romanus” lesions in ankylosing spondylitis demonstrated by contrast enhanced Gd-DTPA magnetic resonance imaging

Objective. To assess the value of Gd-DTPA magnetic resonance (MR) imaging in the demonstration of marginal destructive discovertebral Romanus lesions in ankylosing spondylitis. Design and patients. A prospective study of Gd-DTPA MR imaging was performed in 39 patients with a clinical diagnosis of ankylosing spondylitis and typical Romanus lesions seen on radiographs of the thoracolumbar spine. MR morphological appearances and signal intensity changes at the discovertebral junctions were analysed and compared with the radiographic findings. Results. Ninety-nine discovertebral junctions with Romanus lesions showed low signal intensity on T1-weighted and high signal on T2-weighted and T1-weighted postcontrast images at the vertebral corners consistent with oedematous hyperaemic inflammatory tissue. There were nine discovertebral junctions with similar MR findings but normal radiographs. Fifty-three discovertebral junctions showed syndesmophyte formation with increased signal intensity on both T1- and T2-weighted images with no contrast enhancement. Sixty-five discovertebral junctions showed a mixture of radiographic features and varied high and low signal changes at the vertebral rim on MR imaging with rims of enhancement in the vertebral body following contrast administration. Conclusion. Gd-DTPA MR imaging demonstrates a variable signal pattern and degree of contrast enhancement which may reflect the evolutionary stages of discovertebral enthesitis in ankylosing spondylitis. MR imaging may identify early erosive changes in radiographically normal vertebra. The role of MR imaging needs further investigation. Received: 6 April 1998 Revision requested: 7 May 1998 Revision received: 26 October 1999 Accepted: 27 October 1999     

Internal carotid artery transposition: another cause of widening of the retropharyngeal space

We present four cases of internal carotid artery (ICA) transposition which caused widening of the retropharyngeal soft tissues. Internal carotid artery transposition is a rare cause of retropharyngeal space enlargement, which can be accurately diagnosed in a non-invasive manner with spiral CT. Radiologists should be aware of this entity in the differential diagnosis of retropharyngeal space enlargement in symptomatic (dysphagia, pulsatile mass) and asymptomatic patients, and alert the clinician of its existence, due to the risk of massive bleeding if neck surgery is to be performed. Received: 7 October 1997; Revision received: 9 February 1998; Accepted: 23 March 1998     

Osteochondroma and secondary synovial osteochondromatosis

Secondary synovial osteochondromatosis (SOC) is a rare disorder caused by a variety of joint disorders. Two unusual cases of secondary SOC are presented. The first patient is a 43-year-old man with extensive SOC developing within a bursa surrounding an osteochondroma of the pubic bone. The second patient is a 23-year-old man who developed florid and progressive SOC of his hip joint following excision of a femoral neck osteochondroma. SOC recurred despite three excisions over a 15-month period. Imaging was useful in pre-operative diagnosis of bursal SOC in the first patient and in detecting multiple recurrences in the second patient. Both cases illustrate prominent SOC developing secondary to osteochondroma. The different hypotheses regarding bursal and secondary SOC are reviewed. Received: 8 October 1998 Revision requested: 28 October 1998 Revision received: 13 November 1998 Accepted: 16 November 1998     

Imaging findings in Langerhans' cell histiocytosis of the liver and the spleen in an adult

We present a case of Langerhans' cell histiocytosis (LCH) of the liver and spleen in an adult. The imaging features are different from those in the few previously reported cases of individual organ involvement by LCH. Received: 22 October 1997; Revision received: 17 March 1998; Accepted: 20 March 1998     

Immunoglobulin D myeloma presenting as an extraosseous soft tissue tumor

We report a 69-year-old man who suffered an extraosseous tumor of immunoglobulin D myeloma (lambda type) in the shoulder girdle, mimicking a primary soft tissue sarcoma. The tumor was isointense with adjacent muscle on T1-weighted MR images, and hyperintense on T2-weighted images. No continuity with the neighboring bone was noted. After administration of gadolinium, the central part of the tumor showed marked contrast enhancement. Although the tumor showed a complete response to the initial chemotherapy, the patient died of the disease 31 months after its initial manifestation. Several bone marrow aspirations and biopsies of the ilium and sternum had shown no increase in plasma cells (range 0.6–1.2%) until the disease became advanced 19 months after its initial manifestation. Received: 1 September 2000 Revision requested: 9 October 2000 Revision received: 11 November 2000 Accepted: 15 November 2000     

Erdheim-Chester disease with intramuscular lipogranuloma

We report on a rare manifestation of Erdheim-Chester disease with intramuscular lipogranuloma. The patient was a 66-year-old man who noted a soft tissue mass in the right quadriceps femoris muscle. Radiographs revealed symmetrical osteosclerosis in the diametaphysis of both femora and tibiae. An open biopsy revealed a proliferation of lipid-laden histiocytes in the femoral bone marrow and the quadriceps femoris muscle. To our knowledge, this is the second case of Erdheim-Chester disease involving muscle. Received: 4 October 1999 Revision requested: 18 November 1999 Revision received: 1 December 1999 Accepted: 2 December 1999