Adult embryonal rhabdomyosarcoma of the nose and paranasal sinuses misdiagnosed as an orbital cellulitis: a case report

¹ENT and Maxillo-Facial Department, University Hospital Center Mohammed VI, Oujda, Morrocco

^&Corresponding author
Mahmoud Hamou, ENT and Maxillo-Facial Department, University Hospital Center Mohammed VI, Oujda, Morrocco

Introduction    

Rhabdomyosarcoma (RMS) is a malignant tumor. It arises from mesenchymal origin and belongs to soft tissue sarcomas with striated muscle differentiation. This tumor is seen mainly in children and adolescents. It is rarely diagnosed in adulthood, representing less than 1% of all solid malignant tumors in adults [1]. We report the case of a 22-year-old young woman with embryonic rhabdomyosarcoma localized in the nasal cavity with orbital invasion. Rhabdomyosarcoma can appear in the paranasal sinuses and secondarily affect the orbit. Thus, it can perfectly reproduce the classic picture of orbital cellulitis with a sinus starting point. Early diagnosis and adequate management are essential in these special situations.

Patient and observation     

A 22-years-old woman, without medical history, pregnant at 15 weeks of amenorrhea, who consulted her treating doctor for a left orbital tumefaction with local inflammatory signs and purulent rhinorrhea evolving since 3 weeks, associated with left lateral cervical lymphadenopathy. Initially, the diagnosis of orbital cellulitis was made and the patient was treated by probabilistic antibiotic therapy. The evolution was marked by the appearance of a non-axil exophthalmia with a progressive decrease in visual acuity (Figure 1). A sino-nasal and orbital MRI was performed showing an expansive lesional process with an heterogeneous contrast enhacement. This process completely fills the left nasal cavity. It extends laterally to the homolateral maxillary sinus through the middle meatus. At the top, it invades the orbit with compression of the optic nerve, and approaches the lower part of the frontal lobe through a bone lysis of the anterior skull base (Figure 2, Figure 3). The patient underwent a biopsy of the endo-nasal tumor. Histopathological examination revealed a diagnosis of embryonal rhabdomyosarcoma by demonstrating a chorion massively infiltrated by an undifferentiated proliferation made of small round cells with irregularly contoured nuclei and an abundant cytoplasm (Figure 4). Immunohistochemistry was positive for anti-myogenin (Figure 5). A medical interruption of pregnancy was decided. In view of the unresectability of the tumor, she received a concomitant radio-chemotherapy. Unfortunately, the patient died after 2 months of treatment.

Discussion     

RMS is a primary malignant tumor. It is the most frequent and common soft tissue sarcoma in the pediatric population, with a specific predilection for the head and neck region [2], exceptional in adults [3]. Concerning the paranasal sinus location, it represents 10% to 15% of RMS of the head and neck in adults [2,3]. RMS is presented under three histological subtypes: embryonal, alveolar and pleomorphic. The embryonic type remains the most frequently encountered subtype and described in ENT pathology with a better prognosis, in 25% of cases, it is located in the nasopharynx or developed in a paranasal sinus cavity [4]. Unlike embryonal RMS, the worst prognosis is attributed to the alveolar subtype that remains the most common in paranasal localization, and pleomorphic RMS is more often found in adults [3,5,6]. Our case reports an embryonic RMS of the adult which is therefore an exceptional clinical presentation. The primary clinical diagnosis of a facial RMS remains difficult. It can easily be mistaken for an abscess or an infection. However, antibiotic resistance, failure of external drainage, and the significant increased volume of the process eventually leads to a biopsy and possible diagnosis of the neoplasm [7], as in our patient's case. RMS has no specific clinical symptoms. Sinus involvement occurs in the form of several episodes of early and repetitive epistaxis associated with exophthalmos or ophthalmoplegia [3]. Imaging does not determine diagnosis. It makes it possible to evaluate the locoregional extension. The CT shows the margins of the process and the ratio of the mass to the vital structures. MRI shows a heterogeneous signal of the process, equal to or more intense than the muscle, it is highly recommended for para-sinusial locations, pterygopalatine fossa and infratemporal fossa for tumor extension [3]. There is a much higher rate of distant metastases in adults than in pediatric groups, positron emission tomography (PET) scanning is highly recommended.

Endoscopy and biopsy are required to confirm the diagnosis. There are not any pathognomonic endoscopic findings in RMS except for the embryonic form, which may have the aspect of a gelatinous nasal polyp [4]. Only histology with immunohistochemistry gives definitive diagnosis, desmin and myogenin seem to be the specific markers for RMS [2,3]. Ideally, the basis of treatment is a combination of surgery and postoperative chemo-radiotherapy [2,3]. The Intergroup Rhabdomyosarcoma study recommends, for operable ENT forms, initial surgical treatment followed by an adapted chemotherapy protocol [6]. When the patient is operable and the mass is surgically resecable, the patient´s prognosis is better. Unfortunately, radical surgery is often impossible due to the proximity of the tumors to a vital structure and postoperative cosmetic morbidity. Radiotherapy may be considered as a therapeutic alternative due to the radiosensitivity of adult RMS. Whatever the treatment, prognosis is extremely poorer in adults than children, it also depends on the primary development site, the histological subtype and the size of the tumor [8]. RMS of the orbit has also been described with a better prognosis. Para-meningeal localization is linked to a high recurence rate with much earlier metastases due to the possibility of intracerebral extension [9]. Distant metastasis occurs, in adults, at the time of diagnosis in 60% of cases. The five-year survival rate is 56% to 65% [9]. The predictive factors for a good prognosis are: an age of less than 20 years, a tumor of less than 5 cm in the major axis, the absence of distant metastases and negative surgical margins [10].

Conclusion     

RMS is a very rare tumor in adults, but this diagnosis should not be ruled out because of its aggressiveness and invasiveness, which requires both urgent diagnostic and adapted treatment. Its risk of metastasis and recurrence requires prolonged clinical and radiological monitoring.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

All the authors have read and agreed to the final manuscript.

Figures     

Figure 1: left eye exophthalmos

Figure 2: MRI axial T1-weighted gadolinium

Figure 3: MRI coronal T1-weighted gadolinuim

Figure 4: anatomopathologic examination of sinus RMS: dense eosinophil aspect of the cytoplasm of certain tumor cells

Figure 5: nuclear tumor cell anti-myogenin antibody immunomarking

References