Pathology teach and tell: solid variant alveolar rhabdomyosarcoma of the orbit

Orbital rhabdomyosarcomas: A review

Rhabdomyosarcoma (RMS) is a highly malignant tumor and is one of the few life-threatening diseases that present first to the ophthalmologist. It is the most common soft-tissue sarcoma of the head and neck in childhood with 10% of all cases occurring in the orbit. RMS has been reported from birth to the seventh decade, with the majority of cases presenting in early childhood. Survival has changed drastically over the years, from 30% in the 1960's to 90% presently, with the advent of new diagnostic and therapeutic modalities. The purpose of this review is to provide a general overview of primary orbital RMS derived from a literature search of material published over the last 10 years, as well as to present two representative cases of patients that have been managed at our institute.

Multidisciplinary management of adult orbital rhabdomyosarcoma*

We report the case of a 52-year-old man who presented with a 10-day history of right eye and eyelid inflammation and intermittent diplopia following blunt trauma to the right eyebrow. The CT and MRI scans revealed an extraconal soft tissue mass on the orbital floor with maxillary and ethmoid sinus wall destruction, which on orbital biopsy was proven to be an Alveolar Rhabdomyosarcoma. The patient had a central retinal vein occlusion due to mass effect that resulted in total visual loss at 2 months. He was referred to oncologists who treated him according to the paediatric RMS protocol and is still in remission at 2-year follow-up. Rhabdomyosarcoma is a rare tumour in adults which requires multi-disciplinary management. This highlights the necessity of considering rhabdomyosarcoma in the differential diagnosis of orbital tumours in any age group.

FOXO1-FGFR1 fusion and amplification in a solid variant of alveolar rhabdomyosarcoma

Rhabdomyosarcoma is the most common pediatric soft tissue malignancy. Two major subtypes, alveolar rhabdomyosarcoma and embryonal rhabdomyosarcoma, constitute 20 and 60% of all cases, respectively. Approximately 80% of alveolar rhabdomyosarcoma carry two signature chromosomal translocations, t(2;13)(q35;q14) resulting in PAX3-FOXO1 fusion, and t(1;13)(p36;q14) resulting in PAX7-FOXO1 fusion. Whether the remaining cases are truly negative for gene fusion has been questioned. We are reporting the case of a 9-month-old girl with a metastatic neck mass diagnosed histologically as solid variant alveolar rhabdomyosarcoma. Chromosome analysis showed a t(8;13;9)(p11.2;q14;9q32) three-way translocation as the sole clonal aberration. Fluorescent in situ hybridization (FISH) demonstrated a rearrangement at the FOXO1 locus and an amplification of its centromeric region. Single-nucleotide polymorphism-based microarray analysis illustrated a co-amplification of the FOXO1 gene at 13q14 and the FGFR1 gene at 8p12p11.2, suggesting formation and amplification of a chimerical FOXO1-FGFR1 gene. This is the first report to identify a novel fusion partner FGFR1 for the known anchor gene FOXO1 in alveolar rhabdomyosarcoma.

Solid variant of alveolar rhabdomyosarcoma mimicking non-Hodgkin lymphoma: case report and review of literature

Alveolar rhabdomyosarcoma is a high-grade neoplasm, which forms about 30% of rhabdomyosarcomas. A rare solid variant has been described. A 14-year-old girl presented with inguinal lymph nodal mass and was treated with 6 cycles of CHOP chemotherapy and local radiation. After 3 months, she presented with generalized lymphadenopathy, pleural and pericardial effusions. A histopathologic diagnosis of solid variant of alveolar rhabdomyosarcoma was made. The skeletal muscle origin was confirmed by positive immunostaining for desmin. A primary site was identified in the lower limb muscles. The patient was treated with salvage chemotherapy but had progressive disease. The pediatric and adolescent cases of this rare tumor reported in English language literature are reviewed. In addition, the importance of biopsy in the diagnosis of suspected lymphomas and the pitfalls of needle aspirations are briefly discussed.