Background/Objectives: Clear cell sarcoma (CCS) is a very uncommon, aggressive soft-tissue sarcoma (STS) with a dismal prognosis. In the current literature, there are very limited data focused on the radiological features of CCS. Our study’s objective was to describe CCS pre-treatment’s peculiar imaging characteristics (MRI above all) and to assess if some radiologic features may predict patients’ outcomes with regard to the occurrence of distant metastases. Methods: Our single-center experience includes all the patients with a histological diagnosis of CCS and available radiological and clinical data: 14 patients (8M, 6F, mean age 39.4 years old) were included. The available pre-treatment MRI or contrast-enhanced computed tomography (CECT) studies were examined using an analytical grid that incorporated characteristics from the most recent STS research. The occurrence of metastatic disease was matched with radiological features from baseline imaging studies. Results: MRI was available in 13 patients and CECT in 1 patient. The mean longest diameter (LD) was 50.5 mm ± 29.2. In 10 cases (71.4%), the tumor was deeply seated. MRI revealed a slightly high signal intensity (SI) on T1-WI and a high SI on T2-WI in every subject. At baseline, metastases were already present in 5/14 (35.7%) patients, 3 more developed metastases during the following 5 years (8/14, 57.1%), and 2 additional developed late-onset metastasis after more than 5 years from the diagnosis (total of 10/14 metastatic patients 71.4%). LD and metastasis at diagnosis were significantly correlated (Pearson correlation = 72%, p-value = 0.004). A pre-treatment LD > 4 cm was significantly associated with the development of distant metastases within 5 years from diagnosis and in subsequent follow-up (p = 0.0003). LD > 4 cm represents an increase in risk of metastatic disease within 5 years and during the course of follow-up (OR = 195.00, 95%CI: 3.36–11285.55, p = 0.01). The presence of MRI signs of macroscopic necrosis represented an increase in risk of metastatic disease within 5 years (OR = 15.00, 95%CI: 1.03–218.31—p = 0.04). Conclusions: The identification of MRI features of aggressive biology is a key element for an early referral to sarcoma centers. In our study, a LD > 4 cm and the presence of MRI signs of macroscopic necrosis at the baseline images resulted in being a predictor of metastatic disease.

Background: Adamantinoma is a very rare primary malignant bone tumor. A histopathological grading is still lacking, and as a result, metastatic risk stratification at diagnosis is challenging. Due to this, imaging could play a role in prognosis prediction and treatment strategy assessment. We aimed to evaluate baseline imaging features and their correlation with the development of metastatic disease. Methods: We retrospectively collected clinical (metastatic disease) and radiological data at baseline (Conventional Radiography, CT, MRI) of all consecutive patients with a histopathological diagnosis of adamantinoma at our sarcoma center between 2006 and 2022. Tumor location, dimensions, main radiological pattern (lytic, sclerotic, mixed), Lodwick–Madewell grading, periosteal reaction, multifocality, soft-tissue extraskeletal component, peritumoral edema, peritumoral enhancement, and vascular invasion were analyzed. Associations between the above-mentioned radiological features and metastatic disease at diagnosis or during follow-up were assessed. Results: Twenty-two patients were included (15 [68.2%] women, median age 27 years old, range 7–58 years old). Six out of twenty-two patients (27.3%) developed distant metastases (only two of them were dedifferentiated adamantinoma): two patients (9%) presented with metastatic disease at diagnosis, while four patients developed metastases during follow-up (18.2%). The following radiological features represent a significant risk for metastatic disease (p = 0.01): (i) presence of an extra-skeletal component (Odds Ratio [OR] = 75.40; 95% CI = 3.15–1802.71), (ii) vascular invasion (OR = 121.00; 95% CI = 4.28–3424.73), (iii) diffuse peritumoral edema (OR = 75.40; 95% CI = 3.15–1802.71), (iv) peritumoral enhancement (OR = 84.33; 95% CI = 2.93–2423.26). All other features analyzed were not significantly associated with the onset of distant metastases. Based on these above-mentioned MRI features, we built two risk models for metastatic disease (excluding peritumoral enhancement, which was not available in five patients, to be applicable on unenhanced MRIs): Model (A) = simultaneous presence of two of those three features (2/3) with a sensitivity of 100% (54.07–100%) and a specificity of 93.75% (69.67–99.84%). Model (B) = simultaneous presence of all three features (3/3) with a sensitivity of 83.33% (35.88–99.58%) and a specificity of 100% (74.1–100%). Conclusions: An accurate evaluation of baseline imaging studies (particularly MRI) in patients affected by adamantinoma may significantly aid in prognosis prediction and the selection of high-metastatic-risk patients. For these patients, strict follow-up controls and more aggressive treatments should be suggested after multidisciplinary discussions in sarcoma centers.