A Case of Transformation of Primary Cutaneous Follicle Center Lymphoma to Diffuse Large B-Cell Lymphoma Involving the Parotid Gland and Cervical Lymph Nodes.

BACKGROUND Transformation of primary cutaneous follicle center lymphoma (PCFCL), a low-grade B-cell non-Hodgkin lymphoma (NHL), into a high-grade NHL is rare with uncertain prognosis and treatment. A case is reported of a 40-year-old man who presented with a scalp mass that was diagnosed histologically as PCFCL. Imaging of the head and neck identified diffuse large B-cell lymphoma (DLBCL) involving the parotid gland and cervical lymph nodes, which responded well to radiation therapy. CASE REPORT A 40-year-old African American man presented with a two-year history of a progressively enlarging scalp mass that measured 10.5×7.1×6.6 cm. Histology showed a low-grade lymphoma with a follicular pattern. Immunohistochemistry was positive for B-cell markers and Bcl-6, consistent with a diagnosis of PCFCL. Computed tomography (CT) identified a 4.9×3.7×3.4 cm mass in the left parotid gland with bilateral cervical lymphadenopathy that had been present for the previous two or three months. The diagnosis of DLBCL was made on histology from a needle biopsy. Treatment began with rituximab, etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin (R-EPOCH) chemotherapy, followed by radiation therapy to the scalp, both sides of the neck, and left parotid gland. At four-month follow-up, combined positron emission tomography (PET) and CT showed only diffuse low-level uptake in the scalp and parotid gland. CONCLUSIONS Transformation of low-grade PCFCL to high-grade DLBCL is rare, and the approach to treatment varies. This case showed a good response to chemotherapy and radiation therapy.

Accuracy and precision of cone-beam computed tomography guided intensity modulated radiation therapy.

PURPOSE: To assess the accuracy and precision of cone-beam computed tomography (CBCT)-guided intensity modulated radiation therapy (IMRT). METHODS AND MATERIALS: A 7-field intensity modulated radiation therapy plan was constructed for an anthropomorphic head phantom loaded with a custom cassette containing radiochromic film. The phantom was positioned on the treatment table at 9 locations: 1 "correct" position and 8 "misaligned" positions along 3 orthogonal axes. A commercial kilovoltage cone-beam computed tomography (kV-CBCT) system (VolumeView, Elekta AB, Stockholm, Sweden) was then used to align the phantom prior to plan delivery. The treatment plan was delivered using the radiation therapy delivery system (Infinity; Elekta AB) 3 times for each of the 9 positions, allowing film measurement of the delivered dose distribution in 3 orthogonal planes. Comparison of the planned and delivered dose profiles along the major axes provided an estimate of the accuracy and precision of CBCT-guided IMRT. RESULTS: On average, targeting accuracy was found to be within 1 mm in all 3 major anatomic planes. Over all 54 measured dose profiles, the means and standard errors of the displacement of the center of the field between the measured and calculated profiles for each of the right-left, anterior-posterior, and superior-inferior axes were +0.08 ± 0.07 mm, +0.60 ± 0.08 mm, and +0.78 ± 0.16 mm, respectively. Agreement between planned and measured 80% profiles was less than 0.4 mm on either side along the right-left axis. A systematic shift of the measured profile of slightly less than 1 mm in anterior and superior directions was noted along the anterior-posterior and superior-inferior axes, respectively. CONCLUSIONS: Submillimeter targeting accuracy can be achieved using a commercial kV-CBCT IGRT system.