martedì 12 dicembre 2000
CT(I-) axial and coronal images show bilateral proptosis, left greater than right, and bilateral extraconal soft tissue density masses in both the anterior and posterior portions of the orbit. The masses are contiguous with the lacrimal glands. No gross evidence of bony destruction.
Diagnosis: Orbital lymphoma
The extra nodal presentation of non-Hodgkin's lymphoma is common. Lymphoid masses account for approximately 10 to 15% of all orbital masses. Lymphoid neoplasms of the orbit include a wide range of classifications ranging from reactive lymphoid hyperplasias to benign pseudotumors to malignant lymphomas. Approximately 75% of patients with orbital lymphoma have or will have systemic lymphoma. The most common cytologic forms of malignant lymphoma involving the orbit are the histiocytic and lymphocytic types. Whether malignant lymphomas actually originate in the orbit and disseminate to the rest of the body or whether they represent metastatic sites remains unknown.
Lymphoid neoplasms of the orbit most commonly present in the sixth or seventh decades. True lymphoid tissue in the orbit is found in both the lacrimal glands and the subconjunctival tissue. Most of the lymphoid neoplasms occur at these two sites. Lymphomas tend to occur in the anterior portions of the orbit, most commonly involving the lacrimal glands, the eyelids and the subconjunctiva. In patients with lymphoma, the development of symptoms tends to be indolent and progressive. Symptomatology depends on whether the disease involves the anterior or retrobulbar portion of the orbit. With retrobulbar disease, patients may present with proptosis, eyelid swelling and pain.
In contrast, patients with pseudo-lymphoma (pseudotumor) present at a younger age with symptoms that develop suddenly and progress rapidly. Extensive signs of inflammation, eyelid erythema, pain, visual loss and motility disturbance may be present. Orbital cellulitis is an important consideration in the differential diagnosis.
CT shows homogeneous, sharply marginated, mildly enhancing mass or masses of soft-tissue density which frequently mold to preexisting structures. No bony erosion or enlargement of the orbit.