Primary cutaneous follicle center lymphoma mimicking folliculitis.

Primary cutaneous follicle center lymphoma (PCFCL) is the most common type of cutaneous B-cell lymphoma. The cutaneous manifestations of PCFCL typically include solitary erythematous or violaceous plaques, nodules, or tumors of varying sizes. Grouped lesions also may be observed, but multifocal disease is rare. We report the case of a 54-year-old woman diagnosed with PCFCL with an unusual clinical presentation resembling folliculitis or Grover disease. Histologic studies demonstrated extensive lymphoma cells in a nodular and diffuse pattern. Immunohistochemical studies demonstrated that the neoplastic cells were positive for CD20, CD79a, BCL-2, and BCL-6; CD3, CD5, and cyclin D1 were negative. These findings were consistent with PCFCL. Further evaluation for systemic disease via positron emission tomography-computed tomography and bone marrow biopsy was unremarkable. Increased awareness of this presentation of PCFCL can facilitate earlier diagnosis and intervention, which may result in improved patient outcomes.