Ocular adnexal lymphoma

Neurological examination computed tomography (CT): Homogeneous. Isodense or slightly hyperdense to extraocular muscles (EOMs).

Lesions usually sculpt themselves to adjacent structures without bony erosion.

Heterogeneous lesions with bony destruction suggest high-grade histology.

Mild to moderate postcontrast enhancement similar to EOM or lacrimal gland (LG).

Calcifications are rarely seen.

Usually has an extraconal epicenter (see Figures 17-1 and 17-2 ) but may extend intraconally.

May involve the lacrimal sac and EOMs.

Irregular infiltration of retrobulbar fat may cause a streaky or “dirty fat” appearance.

Bilateral lesions suggest the presence of systemic disease.

Some say that CT is better than other imaging techniques for demonstrating bone destruction, a feature frequently found in high-grade lymphomas.

Magnetic resonance imaging (MRI) is the preferred method of assessment.

T1 is isointense to hyperintense to cerebral cortex ( Figures 17-2 see , A, and 17-3 , A ).

• T2 is usually homogeneous and isointense to cerebral cortex (see Figure 17-3 , C ).

  

T1 Gd shows homogeneous enhancement with a similar signal to EOM (see Figures 17-2, B, and 17-3, B ).

Demonstrates restricted diffusion with bright diffusion weighted imaging (DWI) images. ^,

OALs have lower ADCs than healthy orbital tissues.

OALs demonstrate the lowest ADCs of most orbital masses, invoking a crucial imaging sign: the “ADC black hole sign” of OL. ^,

Variations in ADC for 1 ^o central nervous system (CNS) lymphoma and glioblastoma can predict clinical outcomes. ^,

The ADC may represent a noninvasive surrogate biomarker for OAL response to therapy. ^,

Using ADC variation as a predictor of therapy response may lessen untoward side effects from ineffective regimens.

OAL, like Sherman often spares nothing in its path. As history records, Sherman’s “March to the Sea” destroyed everything in its path. We suggest “Sherman sign” (see Figures 17-2 and 17-3 ).

Fludeoxyglucose positron emission tomography (FDG-PET) may sometimes demonstrate extranodal lymphomatous sites that cannot be detected by conventional imaging. ^,

PET has a higher sensitivity than CT in these cases.

25% of patients show salmon red patch of swollen conjunctiva.

75% of patients demonstrate diplopia, exopthalmos, ptosis, and restricted ocular movement with an orbital mass.

The orbital mass is more frequently found in the superolateral quadrant adjacent to the LG (although Figures 17-1, 17-2, and 17-3 are located medially or inferiorly).

Generally the mass is painless, but some patients show pain, erythema, and swelling, suggesting an inflammatory etiology.

There is an association between Chlamydia psittaci infection and OAL mucosa associated lymphoid tissue (MALT) lymphoma.

Infection by C. psittaci is usually secondary to infected birds and/or household pets.

The association of C. psittaci and MALT lymphoma varies across different geographical locations.

The incidence of OAL increases with advancing age.