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R A McLeod

Publications and source records attributed to R A McLeod.

At least 19 recordsLinked to original sources
PubMed1992

Aneurysmal bone cyst. A clinicopathologic study of 238 cases.

Aneurysmal bone cyst (ABC) is a nonneoplastic expansile bone lesion that mainly affects children and young adults. Primary ABC is relatively rare, with an incidence one half that of giant cell tumor of bone. In 238 patients with ABC studied in the Mayo Clinic files, more than 80% of the lesions were in long bones, flat bones, or the spinal column. Of the lesions initially treated at the Mayo Clinic, 95% were typical ABC; the rest were "solid" variants. Except for the absence of obvious cavernous channels and spaces, there was no significant histologic difference between solid variant and typical ABC. Radiographically, ABC is an eccentric expansile lesion commonly located at the metaphysis of long bones. Computed tomography and magnetic resonance imaging may show multiple internal septations or fluid levels. In the 153 patients treated, 19% had recurrence after curettage (intralesional excision). Recurrence was most common during the first 2 postoperative years.

Adolescent↗
PubMed1991

MR imaging of synovial sarcoma.

The MR imaging findings in 12 cases of synovial sarcoma are illustrated. The MR appearance most indicative of the tumor is an inhomogeneous septated mass with infiltrative margins located close to a joint, a tendon, or bursae, especially if soft-tissue calcification can be seen on CT scans or plain radiographs.

Adolescent↗
PubMed1991

Sacral insufficiency fractures: an often unsuspected cause of low back pain.

We describe a patient with sacral insufficiency fractures presenting as acute onset low back pain without antecedent trauma. Sacral insufficiency fractures are an often unsuspected cause of low back pain. The clinical presentation and plain radiograph findings can mimic metastatic disease, leading to unnecessary investigations and treatment. However, the location, linearity, and appearance of these fractures on computed tomography is very characteristic and obviates the need for further evaluation.

Aged↗
PubMed1991

Telangiectatic osteosarcoma.

Telangiectatic osteosarcoma is a rare variant of osteosarcoma. In the original report from the authors' institution, a poor prognosis was noted. The authors have updated their experience with this entity. The prognosis for patients with telangiectatic osteosarcoma has improved remarkably. The prognosis in the present series seems to be the same as that for conventional osteosarcoma. Adjuvant chemotherapy seems to help in salvaging patients with metastatic disease. However, in this small series, survival of patients without metastasis is apparently not influenced by whether they received chemotherapy.

Adolescent↗
PubMed1990

Chondrosarcoma of bone in children.

Chondrosarcoma of bone rarely occurs in children. This report analyzes the clinicopathologic features in a series of 47 patients with conventional chondrosarcoma who were less than 17 years of age. Of the 47 cases, 14 were from the Mayo Clinic files, and 33 were from our consultation files. Most of the lesions occurred in the trunk and upper ends of the long bones, with the humerus being the most frequent skeletal site. Twelve of the 47 tumors were secondary. The radiographic findings were the same as those seen in adult chondrosarcoma. Pathologically, the tumors were low grade. En bloc resection is the treatment of choice because of the high incidence of local recurrence with lesser surgical margins. Prognosis in childhood chondrosarcoma is no different from that in adult chondrosarcoma. None of the patients with follow-up data had metastasis.

Adolescent↗
PubMed1990

Low-grade intraosseous osteosarcoma.

A study of 80 well-differentiated osteosarcomas, 16 from the Mayo Clinic files and 64 from our consultation files, revealed that males and females were about equally affected, most of the patients were young adults, and skeletal distribution was similar to the distribution seen in conventional osteosarcoma. Radiographs generally showed poor margination, suggestive of malignancy. Histologically, the tumors were composed of spindle cells with only minimal atypia. Some tumors had bone spicules similar to those seen in fibrous dysplasia. An invasive growth pattern was the most helpful feature in differentiating low-grade osteosarcoma from fibrous dysplasia. Initial treatment was highly variable. Local excision was almost always associated with recurrence. Wide excision was almost never followed by recurrence. The recurrent tumor was a high-grade, conventional osteosarcoma in 15% of the patients, and this was associated with a poor prognosis. Wide excision seems to be the treatment of choice for this very rare variant of osteosarcoma.

Adolescent↗
PubMed1990

Case report 628: Low-grade central osteosarcoma.

In summary, low-grade central osteosarcoma is a clinically recognizable rare subtype of osteosarcoma, representing 1.9% of all osteosarcomas found at the Mayo Clinic. The lesion is locally aggressive but also has the potential for metastasis, particularly after local recurrence. The tumor may be difficult to distinguish radiographically and histologically from benign conditions, particularly fibrous dysplasia. This difficulty has led to inadequate treatment. In most cases, a wide surgical margin achieved by either local resection or amputation should result in a cure. Because of the low metastatic potential of the initial lesion, there seems to be no need for adjuvant chemotherapy.

Adult↗
PubMed1990

Masses of the hand and wrist: detection and characterization with MR imaging.

To assess the value of MR imaging in the detection, delineation, and characterization of mass lesions of the hand and wrist, we reviewed the MR imaging findings of 38 patients referred for evaluation of such lesions. Twenty-five patients had a palpable mass. In an additional 13 patients an occult mass lesion was suspected as the cause of distal ulnar neuropathy. Twenty-two mass lesions (16 benign and six malignant) were detected by MR. All were correctly predicted to be benign or malignant. In nine (56%) of the 16 benign mass lesions, the specific diagnosis was suggested. In the remaining seven benign mass lesions and in the six malignant tumors, the MR findings were not specific enough to permit a diagnosis. Of the 14 patients referred for evaluation of a distal ulnar neuropathy, an occult ganglionic cyst compressing the ulnar nerve was revealed with MR imaging in three. MR imaging of the hand and wrist is accurate in the detection of mass lesions and can correctly distinguish benign from malignant tumors in the majority of cases. Specific diagnoses can be made in certain benign lesions. Occult mass lesions can be confirmed or excluded as the cause of distal ulnar neuropathy with MR imaging.

Adolescent↗
PubMed1990

MR imaging of tumor and tumorlike lesions of bone and soft tissue.

This review examines the role of MR imaging in the diagnosis and staging of tumors and tumorlike lesions of bone and soft tissue. For tumors of bone, the plain radiograph is not only the least expensive diagnostic test but is the most reliable predictor of the histologic nature of a given lesion. Consequently, it should be the first procedure performed and serve as the basis for determining the next step in the patient's evaluation. MR imaging is the examination of choice for staging bone tumors. CT is preferred to MR imaging only when the characteristics of the lesion are inadequately defined on plain radiographs, as may occur in flat bones. Although MR imaging is of limited value in predicting the histology of bone tumors, it is a useful tool for distinguishing round-cell tumors and metastases from stress fractures and medullary infarcts in symptomatic patients with normal radiographs. For depiction of soft-tissue masses, MR imaging is unrivaled. The histologic nature of a soft-tissue mass may, in some instances, be predicted on the basis of its MR appearance and multicentricity. Biopsy of bone and soft-tissue tumors should follow and not precede MR imaging. MR imaging reliably shows change in tumor volume after radiation or chemotherapy. It is less reliable in predicting the amount of tumor necrosis.

Bone Neoplasms↗
PubMed1985

Chondrosarcoma of the chest wall: factors affecting survival.

The cases of 96 patients (55 male and 41 female) with primary chondrosarcoma of the chest wall were reviewed. Ages ranged from 17 to 78 years (median, 53.5 years). The tumor involved the rib in 78 patients and the sternum in 18. Seventy-two patients had treatment at the Mayo Clinic, 28 by wide resection, 25 by local excision, and 19 by palliative excision. There was 1 operative death. Follow-up ranged from 1 to 46 years. Recurrent chondrosarcoma developed in 37 patients. All had local recurrence, and 14 also had metastases. Within 10 years, recurrence had developed in 50% of patients who had local excision and in 17% of patients who had wide resection. Ten-year chondrosarcoma survival (Kaplan-Meier) for patients treated by wide resection was 96%; by local excision, 65%; and by palliative excision, 14% (p less than 0.0001). Tumor grade, tumor diameter, tumor location, and date of operation all had a significant influence on survival. This report documents the natural history of chest wall chondrosarcoma and demonstrates that early wide resection is the treatment of choice.

Adolescent↗
PubMed1979

Renal stones in Wilson's disease.

Fifty-four patients with Wilson's disease were studied with regard to renal stones. Seven of the 45 patients (16 per cent) who underwent roentgenographic procedures of the urinary tract had unequivocal evidence of renal stones. In four of the seven patients with Wilson's disease who had renal stones, the stones were discovered at the time or before the diagnosis of Wilson's disease was made. Of the several possible factors that may predispose patients with Wilson's disease to renal stone formation, the renal tubular acidosis pattern of abnormality in acid-base excretion is probably the most significant. In general, patients with renal stones and unexplained neurologic, bony or hepatic abnormalities should be screened for Wilson's disease by slit-lamp examination, determination of serum copper and ceruloplasmin concentrations, and urinary excretion of copper, particularly if they have relatively alkaline urine.

Acid-Base Equilibrium↗
PubMed1979

Benign tumors.

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Bone Cysts↗
PubMed1979

Hamartoma (mesenchymoma) of the chest wall in infancy.

Chest wall hamartoma, commonly known as mesenchymoma, is very rare in infants and usually present at birth. This lesion is a focal overgrowth of normal skeletal elements, Histologically, it is benign. The radiographic appearance is that of a partially mineralized extrapleural mass involving one or more ribs. Surgical ablation seems to be the proper treatment and is curative. Nine cases of this condition are presented, including long-term follow-up in 4.

Bone Neoplasms↗
PubMed1979

Loop of Henle bicarbonate accumulation in vivo in the rat.

We have carried out perfusion studies on hydropenic and bicarbonate-loaded rats to provide direct in vivo observations on bicarbonate accumulation in the short loops of Henle. Analysis of early distal tubular fluid was made during bicarbonate-free saline perfusion from the end proximal to the early distal site, documenting accumulation of "new" bicarbonate. During perfusion in hydropenic rats, steady-state bicarbonate concentrations were suggested by early distal values of approximately equal to mM, which were independent of perfusion rate and virtually indistinguishable from bicarbonate concentration measured during free flow when filtered bicarbonate was allowed to enter the loop. Thus, loop bicarconate accumulation was apparently sufficient to allow new bicarbonate to enter at a rate comparable to that delivered to the early distal site during free flow, recognizing of course that free-flow delivery rates are the result of complex components of filtration and bidirectional fluxes. In bicarbonate-loaded rats, however, bicarbonate accumulation rates although higher than in hydropenia, were much lower than free-flow delivery rates. Furthermore, early distal bicarbonate concentrations during bicarbonate loading fell as perfusion rate increased, presumably because of a limitation to increasing ionic bicarbonate entry.

Animals↗