Malignant diseases of the orbit include primary and metastatic tumors. Most primary malignant tumors of the orbit in childhood are sarcomas. Tumors of epithelial origin are extremely rare.
The most common primary orbital malignant tumor in children is rhabdomyosarcoma, which is thought to originate from undifferentiated mesenchymal cells. The incidence of this disease (which is found in approximately 5% of pediatric orbital biopsies) exceeds that of all other sarcomas combined. The orbit is the origin of 10% of rhabdomyosarcomas; 25% of these tumors arise elsewhere in the head and neck, occasionally involving the orbit secondarily. The average age at onset is 5–7 years, but rhabdomyosarcoma can occur at any age. Rhabdomyosarcoma in infancy is more aggressive and carries a poorer prognosis.
Although ocular rhabdomyosarcoma usually originates in the orbit, it occasionally arises in the conjunctiva, eyelid, or anterior uveal tract. Presenting signs and symptoms include proptosis (80%–100% of cases), globe displacement (80%), blepharoptosis (30%–50%) (Fig 18-15), conjunctival and eyelid swelling (60%), palpable mass (25%), and pain (10%). Onset of symptoms and signs is usually rapid. Acute, rapidly progressive proptosis with an absence of pain are suggestive of orbital rhabdomyosarcoma. Imaging shows an irregular but well-circumscribed mass of uniform density.
A biopsy is required for confirmation of the diagnosis whenever rhabdomyosarcoma is suspected. The most common histologic type is embryonal, which shows few cells containing characteristic cross-striations. Second in frequency is the prognostically unfavorable alveolar pattern, showing poorly differentiated tumor cells compartmentalized by orderly connective tissue septa. Botryoid (grapelike) or well-differentiated pleomorphic tumors are rarely found in the orbit but may originate in the conjunctiva.
Figure 18-15 Rhabdomyosarcoma in a 4-year-old boy presenting with right upper eyelid ptosis of 3 weeks’ duration and a palpable subcutaneous mass.
Small encapsulated or otherwise well-localized rhabdomyosarcomas should be totally excised when possible. Usually, chemotherapy and radiation are used in conjunction with surgery. Exenteration of the orbit is seldom indicated. Primary orbital rhabdomyosarcoma has a relatively good prognosis. The 5-year survival rates are 74% and 94% for patients with alveolar cell type and those with embryonal cell type, respectively.
Osteosarcoma, chondrosarcoma, and fibrosarcoma can develop in the orbit during childhood. The risk of sarcoma is increased in children with a history of heritable retinoblastoma, particularly when external-beam radiation treatment has been given.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.