Primary intracranial rhabdomyosarcoma of the cerebellopontine angle mimicking a vestibular schwannoma in a child

A rare presentation of a bilateral intracranial parameningeal embryonal rhabdomyosarcoma mimicking vestibular schwannoma in a two-year-old child: a case report

Intracranial parameningeal rhabdomyosarcomas are rare, aggressive, rapidly progressive paediatric malignancies that carry a poor prognosis. The authors report a case of a 2-year-old boy who initially presented with a left facial palsy, ataxia and, shortly after, bloody otorrhoea. MRI imaging was initially suggestive of a vestibular schwannoma. However, there was rapid progression of symptoms and further MRI imaging showed very rapid increase in tumour size with mass effect and development of a similar tumour on the contralateral side. A histological diagnosis of bilateral parameningeal embryonal rhabdomyosarcoma was made. Despite treatment, progression led to hydrocephalus and diffuse leptomeningeal disease, from which the patient did not survive. Few intracranial parameningeal rhabdomyosarcomas have previously been reported and these report similar presenting symptoms and rapid disease progression. However, this is the first reported case of a bilateral intracranial parameningeal embryonal rhabdomyosarcoma which, on initial presentation and imaging, appeared to mimic a vestibular schwannoma.

Diagnosis and management of intraparenchymal rhabdomyosarcoma

BACKGROUND

Intracranial rhabdomyosarcomas represent a rare condition, posing a diagnostic challenge to physicians. Brain intraparenchymal rhabdomyosarcomas are exceptionally rare with poorly understood pathogenesis.

METHODS

Here we report the first adult case of intraparenchymal rhabdomyosarcoma (RMS) with brainstem and cranial nerve involvement. We conducted a literature search using Embase, MEDLINE, and PubMed for published cases of patients with rhabdomyosarcoma of the brain. The keywords used were 'rhabdomyosarcoma' combined with 'intraparenchymal', 'parenchymal', 'cerebral' or 'brain' for title/abstract. Included cases were adult patients (>18 years of age).

RESULTS

A 59-year-old man presents with multiple cranial nerve palsies. MRI revealed a solitary pontine lesion that was not responsive to steroids. No systemic lesions were identified with an extensive imaging workup. A wide range of serum and cerebrospinal fluid tests were non-diagnostic during a ten-month workup until, ultimately, the patient died as a result of aspiration pneumonia. At autopsy, pathological examination on whole-brain autopsy revealed RMS, centred in the left side of pons with extension to the left side of the midbrain and the right side of pons with multiple cranial nerve involvement. There are only 20 adult cases of primary intraparenchymal RMS reported in the literature. Our present case is the first reported adult RMS in this location, with novel molecular information, providing some insight into the pathogenesis of this rare diagnosis.

CONCLUSIONS

Intraparenchymal rhabdomyosarcoma without evidence of systemic primary disease is extremely rare, resulting in delayed diagnosis in some cases, particularly those not amenable to biopsy. The diagnostic challenge posed by this complementary case highlights the importance of maintaining a differential of neoplasm in the face of non-diagnostic investigations to the contrary.

Treatment strategy and long-term outcomes of primary intracranial rhabdomyosarcoma: a single-institution experience and systematic review

OBJECTIVE

Primary intracranial rhabdomyosarcoma (PIRMS) is rare, and the effects of the treatment strategy on overall survival (OS) are unclear. This study aimed to evaluate risk factors pertinent to OS and to propose an optimal treatment strategy.

METHODS

Clinical data of patients with PIRMS treated at Beijing Tiantan Hospital and from the English-language literature between 1946 and 2018 were reviewed. A literature review was performed via Ovid, MEDLINE, Embase, PubMed, Web of Science, and Cochrane databases using the terms "rhabdomyosarcoma," "intracranial," "cerebral," and "brain." Previously published data were processed and used according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

There were 8 males (66.7%) and 4 females with PIRMS at our institution, with a mean age of 24.3 years. Gross-total resection was achieved in 4 patients (33.3%), and adjuvant radiation and chemotherapy were administered in 5 (45.5%) and 3 (27.3%) patients, respectively. After a mean follow-up period of 13.7 months, all patients developed local-regional recurrence and died of the disease. Twenty-nine cases (14 female and 15 male) were reported in the literature with a median age of 9.0 years. After a mean follow-up duration of 18.6 months, 13 patients (44.8%) developed recurrences, 7 patients (24.1%) had extracranial metastasis, and 14 patients (48.3%) died. In the pooled cases, adjuvant radiation (hazard ratio [HR] 0.089, 95% confidence interval [CI] 0.027-0.288, p < 0.001) and age < 10 years (HR 0.227, 95% CI 0.077-0.666, p = 0.007) were independent predictors of good local-regional progression-free survival (LR-PFS). Adjuvant radiation therapy (HR 0.301, 95% CI 0.110-0.828, p = 0.020) and age < 10 years (HR 0.359, 95% CI 0.131-0.983, p = 0.046) were significant predictors for favorable OS in the multivariate model.

CONCLUSIONS

Due to the rarity of the disease, a poor outcome of PIRMS was demonstrated based on the pooled cohort. Use of radiation was associated with improved outcomes and should be considered to improve OS/LR-PFS. Further study is required to identify the optimal treatment regimen.Systematic review no.: CRD42019121249 (crd.york.ac.uk/PROSPERO/).

Intracranial Rhabdomyosarcoma of the Cerebellopontine Angle in a 6-year-old Child: A Case Report

Rhabdomyosarcoma (RMS) is the most common soft-tissue malignancy in children under 15 years of age. Approximately, 35% of RMS cases originate from the head and neck region. Among various sites in the head and neck region, intracranial extension is more likely to occur with parameningeal tumors, which is also considered an unfavorable prognostic factor in children with RMS. About 20% of RMS occurs in a parameningeal site. Intracranial RMS are rare tumors that usually arise from parameningeal sites or metastasis from an extracranial site. Primary intracranial types are even rarer, with only 50 reported cases of primary intracranial RMS in the literature.

Hereby, we report the case of a 6-year-old boy who presented with clinical and radiologic features of a cerebellopontine angle lesion, which turned out to be a RMS.

Two cases of primary supratentorial intracranial rhabdomyosarcoma with DICER1 mutation which may belong to a "spindle cell sarcoma with rhabdomyosarcoma-like feature, DICER1 mutant"

Rhabdomyosarcoma is the most common soft-tissue sarcoma affecting children and adolescents. It is defined as a malignant neoplasm characterized by morphologic, immunohistochemical, ultrastructural, or molecular genetic evidence of primary skeletal muscle differentiation, usually in the absence of any other pattern of differentiation. Primary intracranial rhabdomyosarcoma (PIRMS) is an extremely rare neoplasm, with only 60 cases reported in the literature, and generally has poor prognosis with an overall survival of only 9.1 months. The DICER1 gene encodes an RNA endoribonuclease that plays a key role in gene expression regulation through the production of small RNAs. Herein, we report two cases of PIRMS with somatic DICER1 mutation showing morphological and immunohistochemical evidence of primary skeletal muscle differentiation; the two cases share common clinical features, including young age, supratentorial tumor, and onset of intratumoral bleeding. Although methylation profiling was not performed, both cases shared clinical and pathological characteristics in common with recently proposed methylation entity "spindle cell sarcoma with rhabdomyosarcoma-like features, DICER1 mutant (SCS-RMSlike-DICER1)''. Our cases provide further evidence of the link between primary intracranial sarcoma and DICER1 mutation which may form a distinct entity.

Primary intracranial spindle cell sarcoma with rhabdomyosarcoma-like features share a highly distinct methylation profile and DICER1 mutations

Patients with DICER1 predisposition syndrome have an increased risk to develop pleuropulmonary blastoma, cystic nephroma, embryonal rhabdomyosarcoma, and several other rare tumor entities. In this study, we identified 22 primary intracranial sarcomas, including 18 in pediatric patients, with a distinct methylation signature detected by array-based DNA-methylation profiling. In addition, two uterine rhabdomyosarcomas sharing identical features were identified. Gene panel sequencing of the 22 intracranial sarcomas revealed the almost unifying feature of DICER1 hotspot mutations (21/22; 95%) and a high frequency of co-occurring TP53 mutations (12/22; 55%). In addition, 17/22 (77%) sarcomas exhibited alterations in the mitogen-activated protein kinase pathway, most frequently affecting the mutational hotspots of KRAS (8/22; 36%) and mutations or deletions of NF1 (7/22; 32%), followed by mutations of FGFR4 (2/22; 9%), NRAS (2/22; 9%), and amplification of EGFR (1/22; 5%). A germline DICER1 mutation was detected in two of five cases with constitutional DNA available. Notably, none of the patients showed evidence of a cancer-related syndrome at the time of diagnosis. In contrast to the genetic findings, the morphological features of these tumors were less distinctive, although rhabdomyoblasts or rhabdomyoblast-like cells could retrospectively be detected in all cases. The identified combination of genetic events indicates a relationship between the intracranial tumors analyzed and DICER1 predisposition syndrome-associated sarcomas such as embryonal rhabdomyosarcoma or the recently described group of anaplastic sarcomas of the kidney. However, the intracranial tumors in our series were initially interpreted to represent various tumor types, but rhabdomyosarcoma was not among the typical differential diagnoses considered. Given the rarity of intracranial sarcomas, this molecularly clearly defined group comprises a considerable fraction thereof. We therefore propose the designation "spindle cell sarcoma with rhabdomyosarcoma-like features, DICER1 mutant" for this intriguing group.