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.