PO09: Treatment of Facial Folliculotropic Mycosis Fungoides with High Dose Rate Brachytherapy in Two Fractions

Abstract

<h3>Purpose</h3> To describe the treatment and outcomes for the treatment of folliculotropic mycosis fungoides (FMF) with high dose rate (HDR) brachytherapy in the facial area with complex topography. <h3>Materials and Methods</h3> A 68-year-old male with past medical history of morbid obesity status post gastric bypass, diabetes mellitus, hypertension, and atrial fibrillation was diagnosed with FMF of the face, scalp, trunk and extremities. Patient was referred to radiation therapy due to severe burning pain and pruritus of facial lesions on the nose, upper lip, and left temple after no response with UVA therapy. Electron beam therapy was initially chosen with a prescription of 3600 cGy in 20 fractions, but the resulting treatment plans were highly non-conformal with large dose heterogeneity and poor target coverage. HDR brachytherapy was pursued as an alternate treatment option with a prescription dose of 800 cGy in 2 fractions. Patient setup for simulation included a custom Freiburg flap applicator on an Aquaplast mask using 18 catheters to cover all lesions. Patient was scanned with pink bolus in the nostrils, a lead shield under the lip, and a bite block. Treatment planning was performed using Oncentra (Elekta, Stockholm, Sweden). HDR treatment was delivered using an Elekta Flexitron remote afterloader unit. Bilateral internal tungsten eye shields (Civco, Orange City, IA) were placed prior to treatment to reduce ocular dose. <h3>Results</h3> The drawn target was 25.2cc along the upper lip, bilateral nose, right medial canthus, and left temple. Achieved target coverage was V90% = 98.6%, D90% = 100.5%, and D95% = 95.9%. Skin V150% was 0.12cc. Without eye shield placement, right and left eye D0.01cc were 117.9% and 78.2%, respectively. Right and left lens doses were 99.1% and 69.4%, respectively. Average fractional delivery time was 603.5 seconds with an air kerma strength of 39.0 mGy*m²/s (apparent activity 9.7 Ci). Patient tolerated treatment without complications. At two week follow up, patient showed grade 1 dermatitis of the treatment area with erythema and mild desquamation. Patient has been asymptomatic six months post treatment. <h3>Conclusions</h3> Low dose HDR brachytherapy can be an effective treatment for facial FMF lesions with complex topography. It allows for suitable target coverage and normal tissue sparing, a shorter treatment course when compared to electron beam radiotherapy, and is associated with minimal adverse effects and rapid clinical response. It also allows sparing total skin electron therapy for the future in case of disease progression as the volume of tissue receiving radiation is very small. Figure 1a: Oncentra treatment plan in axial, sagittal, and coronal planes, with 3D rendering show in bottom right. Target volume in light blue, right eye in green, and left eye in blue. 1b shows wires outlining the target volume (top); pre-mask setup with pink bolus, bite block, gauze in the nostrils, and bilateral eye shields (middle); and final treatment setup with mask (bottom). 1c shows the pre-treatment lesions, and 1d shows the same area four months post treatment.