Is there a role for radiation therapy in the treatment of a lymphoproliferative disorder involving the orbit?

The great majority of lymphoproliferative disorders of the orbit turn out to be NHL when subjected to sophisticated pathologic evaluation, but even those which are considered benign lymphoid hyperplasia (LH) are often and successfully treated with radiotherapy. The dose of RT for low-grade lymphoma and certainly for LH has decreased in recent years to 20-24 GY, 1.8- 2 Gy per fraction. For benign LH 20 Gy is appropriate. Typically the field encompasses the entire orbit. Don't miss! At that dose, the main side effect is radiation cataracts, fortunately, easy to correct surgically. A good recent review of LH may be found in Andrew et al., PMID 27127077

When I don't have pathology/flow/PCR reports diagnostic of malignancy, I have treated patients with "lymphoid atypia", "atypical lymphoid infiltrate", or "lymphoproliferative disorder" with symptomatic disease to 4 Gy in 2 fractions. I have a collection of such patients (about a dozen), almost all of whom have remained disease free. My goal in this setting where I have no diagnosis of malignancy is to minimize risk with a regimen that may provide benefit. Challenging area to manage.

To confirm the diagnosis of orbital lesion, biopsy (monoclonal small B cell lymphoma) is needed. To differentiate the reactive LH from the atypical forms (IgG related diseases), advanced molecular tests such as IHC and PCR (rearrangement of IG heavy chain gene (JH) and/or light chain gene, [J kappa] and monoclonal V-J recombination of JH) are performed to confirm the BLH of orbit. Radiation is the treatment of choice for the BLH of the orbit (20-30 Gy in 10-15 fractions) and has proven to reduce the local recurrence of BLH and improve OS (Keleti et al., PMID 1524043). Though RT is the treatment of choice, some atypical forms can infiltrate into choroid or orbit or can transform to NHL over the years and thus need Rituxan or oral steroids. R...

IgG4 related disease is also a potential cause of lymphoproliferative disorder, as noted in Dr. @Dr. First Last's answer.

If a patient has IgG4 disease, would you still recommend radiation therapy, or suggest other treatment?