A rare case of embryonal rhabdomyosarcoma of the parapharyngeal space

CT and MR imaging features of soft tissue rhabdoid tumor: compared with rhabdomyosarcoma in children

Objective

To assess the computed tomography (CT) and magnetic resonance (MR) imaging characteristics of soft tissue rhabdoid tumors (RT) and compare them with those of rhabdomyosarcoma (RMS).

Methods

We conducted a retrospective analysis of 49 pediatric patients from 2011 to 2022, comprising 16 patients with soft tissue RT and 33 patients with RMS who underwent CT or MRI scans. Key imaging features, as well as clinical and pathological data, were compared between the two groups. The multivariate logistic regression analysis was used to determine independent differential factors for distinguishing soft tissue RT from RMS, and the model was established. The final prediction model was visualized by nomograms and verified internally by using a bootstrapped resample 1,000 times. The diagnostic accuracy of the combined model was assessed in terms of discrimination, calibration, and clinical utility.

Results

Age, sex, number of lesions, and primary locations were similar in both groups. The imaging characteristics, including margin, calcification, surrounding blood vessels, and rim enhancement, were associated with the two groups of soft tissue tumors, as determined by univariate analysis (all p < 0.05). On multivariate logistic regression analysis, the presence of unclear margin (p-value, adjusted odds ratio [95% confidence interval]: 0.03, 7.96 [1.23, 51.67]) and calcification (0.012, 30.37 [2.09, 440.70]) were independent differential factors for predicting soft tissue RT over RMS. The presence of rim enhancement (0.007, 0.05 [0.01, 0.43]) was an independent differential factor for predicting RMS over soft tissue RT. The comprehensive model established by logistic regression analysis showed an AUC of 0.872 with 81.8% specificity and 81.3% sensitivity. The decision curve analysis (DCA) curve displayed that the model achieved a better net clinical benefit.

Conclusion

Our study revealed that the image features of calcification, indistinct margins, and a lack of rim enhancement on CT and MRI might be reliable to distinguish soft tissue RT from RMS.

Embryonal Rhabdomyosarcoma of the Tongue in Adults

(1) Background: Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the first two decades of life. One third of cases appear in the head and neck, with 60% of these being embryonal type. RMS is extremely rare in adults, comprising only 1% of adult malignancies, and of those, only 3.3% are rhabdomyosarcomas. (2) Case report: A 46 y.o. male presented with a 1 cm exophytic pediculated painless lesion on the dorsum of his tongue, with progressive growth for 3 months. An excisional biopsy revealed an "embryonal rhabdomyosarcoma with fusocellular areas, with negative rearrangement for gen FOXO1A, negative MDM2 (only focal positivity), and positive INI-1". Subsequent contrast-enhanced MRI concluded the presence of a lesion with imprecise margins in the right half-tongue, 15 × 8 × 7 mm (longitudinal × transverse × craniocaudal), compatible with a sarcoma. The patient underwent a partial centrolingual glossectomy followed by reconstruction with a buccinator muscle local flap. After surgery, he received chemotherapy with eight cycles of VAC (vincristine, actinomycin, and cyclophosphamide) protocol. The patient is now disease free after 42 months, with good tongue function. (3) Discussion and conclusions: Embryonal RMS is an extremely rare sarcoma in adults, and the location in the tongue is even more exceptional (only two more similar cases are reported in the literature). The prognosis in adults is significantly poorer than in children. A complete margin-free resection with an adequate chemotherapy protocol is the treatment of choice in cases such as these.

Fisher discriminant model based on LASSO logistic regression for computed tomography imaging diagnosis of pelvic rhabdomyosarcoma in children

Computed tomography (CT) has been widely used for the diagnosis of pelvic rhabdomyosarcoma (RMS) in children. However, it is difficult to differentiate pelvic RMS from other pelvic malignancies. This study aimed to analyze and select CT features by using least absolute shrinkage and selection operator (LASSO) logistic regression and established a Fisher discriminant analysis (FDA) model for the quantitative diagnosis of pediatric pelvic RMS. A total of 121 pediatric patients who were diagnosed with pelvic neoplasms were included in this study. The patients were assigned to an RMS group (n = 36) and a non-RMS group (n = 85) according to the pathological results. LASSO logistic regression was used to select characteristic features, and an FDA model was constructed for quantitative diagnosis. Leave-one-out cross-validation and receiver operating characteristic (ROC) curve analysis were used to evaluate the diagnostic ability of the FDA model. Six characteristic variables were selected by LASSO logistic regression, all of which were CT morphological features. Using these CT features, the following diagnostic models were established: (RMS group)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${G}_{1}=-14.283+6.613{x}_{1}+5.333{x}_{2}+5.753{x}_{3}+12.361{x}_{4}+8.095{x}_{5}-0.715{x}_{6}$$\end{document}G1=-14.283+6.613x1+5.333x2+5.753x3+12.361x4+8.095x5-0.715x6; (Non-RMS group)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${G}_{2}=-2.008+3.539{x}_{1}+1.080{x}_{2}+1.154{x}_{3}+2.307{x}_{4}+1.656{x}_{5}+1.380{x}_{6}$$\end{document}G2=-2.008+3.539x1+1.080x2+1.154x3+2.307x4+1.656x5+1.380x6, where \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${x}_{1}$$\end{document}x1, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${x}_{2}$$\end{document}x2, … and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${x}_{6}$$\end{document}x6 are lower than normal muscle density (1 = yes; 0 = no), multinodular fusion (1 = yes; 0 = no), enhancement at surrounding blood vessels (1 = yes; 0 = no), heterogeneous progressive centripetal enhancement (1 = yes; 0 = no), ring enhancement (1 = yes; 0 = no), and hemorrhage (1 = yes; 0 = no), respectively. The calculated area under the ROC curve (AUC) of the model was 0.992 (0.982–1.000), with a sensitivity of 94.4%, a specificity of 96.5%, and an accuracy of 95.9%. The calculated sensitivity, specificity and accuracy values were consistent with those from cross-validation. An FDA model based on the CT morphological features of pelvic RMS was established and could provide an easy and efficient method for the diagnosis and differential diagnosis of pelvic RMS in children.

Surgical Interventions for Advanced Parameningeal Rhabdomyosarcoma of Children and Adolescents

Owing to its rarity, rhabdomyosarcoma of the head and neck (HNRMS) has seldom been discussed in the literature. As most of the data is based only on the retrospective experiences of tertiary healthcare centers, there are difficulties in formulating a standard treatment protocol. Moreover, the disease is poorly understood at its pathological, genetic, and molecular levels. For instance, 20% of all histological assessment is inaccurate; even an experienced pathologist can confuse rhabdomyosarcoma (RMS) with neuroblastoma, Ewing’s sarcoma, and lymphoma. RMS can occur sporadically or in association with genetic syndromes associated with predisposition to other cancers such as Li-Fraumeni syndrome and neurofibromatosis type 1 (von Recklinghausen disease). Such associations have a potential role in future gene therapies but are yet to be fully confirmed. Currently, chemotherapies are ineffective in advanced or metastatic disease and there is lack of targeted chemotherapy or biological therapy against RMS. Also, reported uses of chemotherapy for RMS have not produced reasonable responses in all cases. Despite numerous molecular and biological studies during the past three decades, the chemotherapeutic regimen remains unchanged. This vincristine, actinomycin, cyclophosphamide (VAC) regime, described in Kilman, et al. (1973) and Koop, et al. (1963), has achieved limited success in controlling the progression of RMS. Thus, the pathogenesis of RMS remains poorly understood despite extensive modern trials and more than 30 years of studies exploring the chemotherapeutic options. This suggests a need to explore surgical options for managing the disease. Surgery is the single most critical therapy for pediatric HNRMS. However, very few studies have explored the surgical management of pediatric HNRMS and there is no standard surgical protocol. The aim of this review is to explore and address such issues in the hope of maximizing the number of options available for young patients with HNRMS.