giovedì 13 maggio 2010
Poorly differentiated orbital malignant lymphoma
Figure 1: Axial CT through the orbital floors at the level of the inferior orbital foramen demonstrates an erosive mass, containing calcifications, with expansion through the floor of the orbit and into the maxillary sinus.
Figure 2: Contrast enhanced coronal CT image demonstrates a heterogeneously enhancing, soft tissue mass involving the floor of the orbit, with bony invasion.
Diagnosis: Poorly differentiated orbital malignant lymphoma (Non-Hodgkin's type) (biopsy proven)
In the adult population the differential diagnosis of malignant orbital tumors differs from that of children. Whereas, carcinoma is the frequently enountered in adults (often from contiguous spread from the paranasal sinus, etc), metastatic neuroblastoma is the more frequently encountered malignant neoplasm in children.
Neoplasms of the paranasal sinuses are uncommon, but frequently extend to involve the orbit when they do occur. Benign tumors tend to push the periorbital tissues aside, while malignant lesions tend to invade the periosteum.
Evaluation of the paranasal sinus mass is best done utilizing multidetector CT, because of its ability to detect bony destruction and possible intracranial extension of disease. CT usually demonstrates a homogeneous mass with well-defined borders that demonstrates heterogeneous enhancement.
Lymphoid tumors are one of the most common orbital tumors despite the orbit not containing lymph nodes or a well defined lymphatic vasculature. Ocular malignant lymphomas are uncommon. The incidence ranges from 1-4%. Involvement of the orbit as a presenting sign is rare and few such cases are seen in the literature. Although most orbital lymphomas are localized to the orbit at diagnosis, many patients will develop systemic lymphoma over time. Orbital lymphoma is an adult disease, usually presenting in patients between the age of 50-70 years. The course is usually of an anterior mass that causes painless proptosis over several weeks to months.
Radiation therapy is the mainstay of treatment since surgical resection plays a limited role. Response rate and prognosis depends upon cell type, the extent of disease and whether the orbital disease represents the primary site or the site of spread of disease from an extra-ocular primary. Five year survival rates range from 54-78%.