Imaging features and differences among the three primary malignant non-Wilms tumors in children

Abstract

Background The pathology, treatment and prognosis of malignant non-Wilms tumors (NWTs) are different, so it is necessary to differentiate these types of tumors. The purpose of this study was to review the clinical and imaging features of malignant NWTs and features of tumor metastasis. Methods We retrospectively analyzed the CT images of 65 pediatric patients with NWTs from March 2008 to July 2020, mainly including clear cell sarcoma of the kidney (CCSK), malignant rhabdomyoma tumor of the kidney (MRTK) and renal cell carcinoma (RCC). Available pretreatment contrast-enhanced abdominal CT examinations were reviewed. The clinical features of the patients, imaging findings of the primary mass, and locoregional metastasis patterns were evaluated in correlation with pathological and surgical findings. Results The study included CCSK (22 cases), MRTK (27 cases) and RCC (16 cases). There were no significant differences observed among the sex ratios of CCSK, MRTK and RCC (all P > 0.05). Among the three tumors, the onset age of MRTK patients was the smallest, while that of RCC patients was the largest (all P < 0.05). The tumor diameter of CCSK was larger than that of MRTK and RCC (all P < 0.001). For hemorrhage and necrosis, the proportion of MRTK patients was larger than that of the other two tumors (P = 0.017). For calcification in tumors, the proportion of calcification in RCC was highest (P = 0.009). Only MRTK showed subcapsular fluid (P < 0.001). In the arterial phase, the proportion of slight enhancement in RCC was lower than that in the other two tumors (P = 0.007), and the proportion of marked enhancement was the highest (P = 0.002). In the venous phase, the proportion of slight enhancement in RCC was lower than that in the other two tumors (P < 0.001). Only CCSK had bone metastasis. There was no liver and lung metastasis in RCC. Conclusions NWTs have their own imaging and clinical manifestations. CCSK can cause vertebral metastasis, MRTK can cause subcapsular effusion, and RCC tumor density is usually high and calcification. These diagnostic points can play a role in clinical diagnosis.

Çocuklarda Wilms tümörü dışındaki böbrek tümörlerinde risk grubunun sağkalıma etkisi

“…One patient in our study was diagnosed with PNET histopathologically via mass excision during nephrectomy; however, despite the surgery and subsequent chemotherapy, the patient died due to the disease progression. MRT (41.6%) was found to be the most common, followed by CCSK (33.8%) and RCC (24.6%) 13 .…”

Similarities and controversies in imaging of pediatric renal tumors: A SIOP‐RTSG and COG collaboration

“…Besides clinical presentation, mainly based on age or unusual metastatic patterns, imaging findings that are uncommon for WTs (as defined in the SIOP‐RTSG 2016 UMBRELLA protocol, which is further referred to as the UMBRELLA protocol) include numerous calcifications, voluminous lymphadenopathy, nonvisible renal parenchyma, and/or the identification of a near‐complete extra‐renal process 7,14 . Apart from these characteristics, the discrimination of pediatric renal tumors based on solely CT or MRI characteristics remains challenging 11,33 …”

“…The most important differentiation for both the COG and SIOP‐RTSG is between WTs and non‐WTs, and this remains challenging with current imaging modalities. The challenge to discriminate WTs from non‐WTs is mainly due to the high incidence and heterogeneous appearance of WTs 14,33 . However, certain imaging features can suggest a diagnosis other than WT.…”

“…For example, numerous calcifications are often mentioned as indicative for non‐WTs, and are best identified on US and CT 34–37 . In case of a synchronous intracranial tumor, an RTK should be strongly considered, as well as in case of pulmonary metastases at young age 3,11,33,36,38 . While some studies have suggested that subcapsular fluid is indicative of RTKs, this finding maybe seen with WT as well 11,36 .…”

“…While some studies have suggested that subcapsular fluid is indicative of RTKs, this finding maybe seen with WT as well 11,36 . CCSK is highly suspected when bone metastases are detected on cross‐sectional for staging of a renal mass, nevertheless, these are still rather infrequently observed 33,39–42 . In addition, CCSKs may show a similar presentation to stromal WTs, given their stromal pattern with fine vasculature 43 .…”