Intramuscular diffuse-type giant cell tumor within the hamstring muscle

Incidental findings in the skeletal musculature on computed tomography

OBJECTIVE

The purpose of this study was to analyze intramuscular incidental findings identified on CT in a large patient cohort.

METHODS

In the time period from 2010 to 2015, a total of 44,794 patients with several diagnoses were investigated by CT. Only those patients who underwent body CT including the neck, thorax, abdomen and pelvic regions after the i.v. application of a contrast medium were involved in the study. There were 4085 patients. On further analysis, only patients with intramuscular findings (IFs) incidentally detected on CT were included. Osseous or soft-tissue lesions with invasion into the musculature were excluded from the study. Patients with known or clinically suspicious muscle disorders were also excluded. Overall, 639 (15.64% of the 4085 analyzed cases) patients, 253 females and 386 males, with mean age 72.43 ± 12.02 years, were identified. Collected data were evaluated by means of descriptive statistics.

RESULTS

In the 639 patients, 917 IFs were identified. More often, several benign disorders were diagnosed (n = 803, 87.6%). There were hernias (33.5%), atrophy of different muscles (22%), lipomas (21%), intramuscular calcifications (8.7%), bursitis (1.2%) and intramuscular bleeding (1.1%). Malignant IFs (n = 114, 12.4%) included intramuscular metastases (11.9%) and lymphomas (0.6%). Most frequently, the identified IFs were localized in the abdominal wall musculature, paravertebral and gluteal muscles. In 657 cases (71.6% of all IFs), the identified muscle findings were not diagnosed by the radiologist who initially assessed the investigation.

CONCLUSION

CT can detect different incidental disorders within the skeletal musculature. Most of them were benign. However, malignant lesions can also occur. Therefore, skeletal muscles should be carefully evaluated on CT performed for other reasons. Advances in knowledge: IFs occur in 15.6% of CT investigations. Benign findings represent 87.6% and malignant lesions can be identified in 12.4%.

Nonsurgical giant cell tumour of the tendon sheath or of the diffuse type: are MRI or 18F-FDG PET/CT able to provide an accurate prediction of long-term outcome?

PURPOSE

To investigate whether MRI (RECIST 1.1, WHO criteria and the volumetric approach) or (18)F-FDG PET/CT (PERCIST 1.0) are able to predict long-term outcome in nonsurgical patients with giant cell tumour of the tendon sheath or of the diffuse type (GCT-TS/DT).

METHODS

Fifteen "nonsurgical" patients with a histological diagnosis of GCT-TS/DT were divided into two groups: symptomatic patients receiving targeted therapy and asymptomatic untreated patients. All 15 patients were evaluated by MRI of whom 10 were treated, and a subgroup of 7 patients were evaluated by PET/CT of whom 4 were treated. Early evolution was assessed according to MRI and PET/CT scans at baseline and during follow-up. Cohen's kappa coefficient was used to evaluate the degree of agreement between PERCIST 1.0, RECIST 1.1, WHO criteria, volumetric approaches and the reference standard (long-term outcome, delay 505 ± 457 days). The response rate in symptomatic patients with GCT-TS/DT receiving targeted therapy was also assessed in a larger population that included additional patients obtained from a review of the literature.

RESULTS

The kappa coefficients for agreement between RECIST/WHO/volumetric criteria and outcome (15 patients) were respectively: 0.35 (p = 0.06), 0.26 (p = 0.17) and 0.26 (p = 0.17). In the PET/CT subgroup (7 patients), PERCIST was in perfect agreement with the late symptomatic evolution (kappa = 1, p < 0.05). In the treated symptomatic group including the additional patients from the literature the response rates to targeted therapies according to late symptomatic assessment, and PERCIST and RECIST criteria were: 65 % (22/34), 77 % (10/13) and 26 % (10/39).

CONCLUSION

(18)F-FDG PET/CT with PERCIST is a promising approach to the prediction of the long-term outcome in GCT-TS/DT and may avoid unnecessary treatments, toxicity and costs. On MRI, WHO and volumetric approaches are not more effective than RECIST using the current thresholds.

Infiltration of the pes anserinus complex by an extraarticular diffuse-type giant cell tumor (D-TGCT)

This report describes the case of a 26-year-old woman with a recurrent extraarticular diffuse-type tenosynovial giant cell tumor (D-TGCT) of the medial region of the knee affecting the pes anserinus and hamstring tendons. Presurgical MRI did not exclude infiltrative properties of the tumor. In the histological evaluation, the tumor showed an aggressive dispersion by infiltrating the collagenous tissue of the hamstring tendons. The treatment included a resection of the pes anserinus complex with distal semitendinosus and gracilis tendons. Regarding extraarticular D-TGCT a review of the literature showed a predominant affection of the medial region of the knee and thigh.