Orbital rhabdomyosarcoma, a common soft tissue sarcoma
Rhabdomyosarcoma (RMS) is a highly malignant tumour that is one of the few life-threatening diseases that first manifests itself to an ophthalmologist. It is the most common soft-tissue sarcoma of the head and neck in childhood, accounting for 10% of all cases. Orbital rhabdomyosarcoma has been reported in people ranging in age from birth to the seventh decade, with the majority of cases presenting in childhood. With the introduction of new diagnostic and therapeutic modalities, survival has increased dramatically over the years, from 30% in the 1960s to 90% today.
Malignant orbital tumours are becoming more common in general
Rhabdomyosarcoma (RMS) is a highly malignant tumour that arises from pluripotent mesenchyme. It is the most common soft-tissue sarcoma of the head and neck in childhood, accounting for 4% of all paediatric malignancies, with the orbit accounting for 10% of all cases. The majority of these tumours develop during the first decade of life, but RMS has been reported from birth to the eighth decade.
Malignant orbital tumours are becoming more common in general. Turner et al. reported an annual percentage increase of 1.16% and statistically unchanged 5-year survival over the past 30 years in a study of population-based incidence and survival in head and neck RMS, despite advances in treatment modalities; however, other studies have reported improved survival. Relative survival (RS) was determined by the extent of disease rather than the primary site, and it was discovered that most orbital RMS tumours (60.6%) presented with localised disease, resulting in a 5-year survival rate of about 84.3%, which is higher when compared to other sites in the head and neck. Other factors that contributed to survival included younger age, less than 10 years, female sex, and embryonal histology.
Ocular RMS refers to tumours that develop in the orbit or, in rare cases, in other ocular adnexal structures or within the eye. 2 The goal of this review is to provide a general overview of primary orbital RMS based on a literature search of material published in the last decade, as well as to present two representative cases of patients managed at our institute.
Because orbital RMS is one of the few life-threatening diseases that present first to an ophthalmologist, prompt diagnosis and treatment is critical. As a result, understanding the clinical, histopathological, and radiographic features of this entity, as well as recent advances in its management, is critical.
Case study
A previously healthy 8-year-old boy presented to the emergency department complaining of painless swelling of the right lower eyelid for two weeks. Physical examination revealed that the swelling was present during primary gaze (Panel A) but diminished during downward gaze (see video). Within the eyelid, a fixed mass measuring 1.5 cm by 2.5 cm was palpable. When the right eyelid was lifted, erythematous subconjunctival tissue protruded from beneath the lower eyelid (Panel B). The patient was diagnosed with orbital rhabdomyosarcoma.
Both eyes’ visual acuity and extraocular movements were normal. Magnetic resonance imaging of the orbits revealed a heterogeneous, circumscribed, T1-hypointense, T2-hyperintense mass along the right globe’s anteroinferior portion (Panel C, T1 fat-suppression sequence with contrast medium). Histopathological examination revealed dense sheets of small, round, blue cells stained positive for myogenin after an incisional biopsy (Panel D). The most common primary malignant orbital tumour in children, embryonal rhabdomyosarcoma, was diagnosed. Following a staging evaluation, the patient underwent mass debulking, adjuvant chemotherapy, and radiotherapy.
Three months later, imaging revealed no signs of disease, and the patient’s vision remained normal. Eyelid swelling that varies with eye movement, as in this case, should raise suspicion for an extraocular muscle condition, including malignant tumours.
Source: NEJM
