2851 - Moderate Hypofractionated Radiation Therapy for Rosai-Dorfman Disease

Purpose/Objective(s):

Rosai–Dorfman disease (RDD) is a rare non–Langerhans cell histiocytic disorder. Although asymptomatic patients are often managed with observation, treatment is indicated for those with symptomatic or clinically threatening disease. Surgical resection is generally preferred for localized, resectable lesions. However, many patients present with disease that is not technically resectable or for which surgery would be associated with substantial morbidity. Radiation therapy (RT) represents a potential therapeutic option in this setting, yet published experience is limited. Existing national guidelines lack granular recommendations, including optimal radiation dose. Herein, we report a small series of patients treated in a uniform manner using a moderately hypofractionated radiation regimen.

Materials/Methods:

All adult patients (=18 years) with pathologically confirmed RDD who were treated with RT at our institution between 2022 and 2026 were evaluated. Given the limited sample size, analyses were descriptive with summary statistics.

Results:

We identified 5 patients treated to 6 sites during the time period (Table). Localized disease was present in 4 patients and multifocal disease in 1 (both sites treated with RT). Prior treatment had been administered to 4/5 patients including systemic therapy (n=4), surgery (n=2), low-dose RT (n=1), and/or curettage (n=1). RT consisted of IMRT in 4 and 3D-CRT in 2. All patients received 3 Gy fractions to 36-39 Gy. Clinical and radiological outcomes are shown in the enclosed table. With the exception of ovarian dysfunction in one patient, there were no other long-term complications from RT. No patients have progressed symptomatically or radiologically at the treated site.

Conclusion:

The optimal management of RDD remains unclear. Patients are increasingly referred for consideration of RT. While initial results with this hypofractionated approach are promising, further follow-up is needed.

Patient	Site	Symptom	RT Dose	Clinical Response	Imaging Response	Follow-up
72F	Ilium/sacrum	Back/hip pain	36 Gy/3 Gy	Resolution of pain	CR (PET-CT)	2y
75F	Hilum	Dyspnea	36 Gy/3 Gy	Resolution of dyspnea	PR (PET-CT)	2y
	Cranial nerves	Pain/Decreased sensation	36 Gy/3 Gy	Resolution of pain/ Stable paresthesias	SD (MRI)	8m
54M	Tibia	Knee pain/Leg weakness	39 Gy/3 Gy	Stable symptoms	CR (PET-CT)	1y
38F	Pre-sacral mass	GI bleed/Pelvic pain	36 Gy/3 Gy	Resolution of bleeding and pain	SD (PET-CT)	3m
38M	Orbit	Proptosis/Diplopia	36 Gy/3 Gy	Pending	Pending	Pending