Clinical History
An 8-year-old Caucasian male patient presented with a large, swollen, left-sided facial mass and proptosis of the left eye.
Imaging Findings
We present the case of a previously healthy child, who presented to our Accident & Emergency department with a left facial mass, which extended into the left eye.
CT and MRI imaging revealed a destructive tumour occupying the left anterior ethmoid cells and upper nasal cavity. The tumour mass extended laterally into the left upper part of the orbit and also involved the medial part of the left maxillary antrum. Further extension was seen across the midline into the right anterior ethmoid sinuses.
After the patient was examined by the otolaryngologist, a biopsy was performed. Histology and immunohistochemistry confirmed a diagnosis of extrarenal rhabdoid tumour.
The specific imaging characteristics of such soft tissue rhabdoid tumours have yet to be determined because of both their rarity and relatively recent recognition.
Discussion
Malignant rhabdoid tumours are rare and aggressive malignancies that consist of both renal and extrarenal subtypes, and make up 2 % of paediatric malignancies [1].
They were initially described in 1978 as a rhabdomyosarcomatoid variant of Wilms’ tumour, in the National Wilms' Tumor Study - a comprehensive databank of paediatric renal tumours. As the tumour resembled rhabdomyosarcoma under the light microscope, but lacked rhabdomyoblastic features, it was identified as “rhabdoid” tumour.
The commonest documented extrarenal sites of this disease entity are thymus, liver, paravertebral region, central nervous system, heart, prostate, pelvis, chest wall, tongue, neck. extremities and soft tissues [2]. There is no apparent correlation of age and site predilection, and these tumours occur in both adults and children.
The histopathological diagnosis of an extra-renal rhabdoid tumour is based on the presence of specific cytological features, similar to those demonstrated in malignant rhabdoid tumour of the kidney. Large oval to polygonal cells with abundant eosinophilic cytoplasm, large vesicular nuclei with prominent nucleoli and conspicuous filamentous cytoplasmic inclusions are seen [3]. Even though these criteria form the primary basis for the diagnosis of an extra-renal rhabdoid tumour, they are non-specific and have been reported in other tumours e.g. melanoma, rhabdomyosarcoma, colonic adenocarcinoma and several benign conditions [2].
Immunohistochemistry is also helpful to diagnose an extra-renal rhabdoid tumour. This shows rhabdoid cells, which are positive for cytokeratin, vimentin and epithelial membrane antigen. Extra-renal rhabdoid tumours are an heterogeneous group of neoplasms comprising unrelated tumours with rhabdoid cells, tumours of apparent neuroectodermal derivation with polyphenotypic features and a small group of primitive neoplasms that are difficult to categorise. The most frequent cause of death is pulmonary metastases, followed by local invasion from intra-abdominal tumours [2].
The management of these tumours is variable, dependant upon severity. The recommended chemotherapy regimen consists of vincristine, actinomycin D and doxorubicin given at 3 week intervals for a total of 1 year. The evidence available indicates that despite the extremely poor prognosis associated with extra-renal rhabdoid tumours, an aggressive surgical excision and radiation therapy in the setting of localised disease can result in long-term survival [4].
Differential diagnosis for the described patient include orbital rhabdomyosarcoma, which presents as a space-occupying lesion, and may mimic other neoplastic or inflammatory masses; this tumour has predilection for the superior nasal quadrant of the orbit. Imaging demonstrates bone invasion, and extension of the tumour into the intracranial cavity and paranasal sinuses [5].
Differential Diagnosis List
Malignant extra-renal rhabdoid tumour.
Rhabdomyosarcoma
Nonrhabdomyosarcoma soft tissue sarcomas
Final Diagnosis
Malignant extra-renal rhabdoid tumour.
