Primary cutaneous peripheral T‐cell lymphoma, not otherwise specified, associated with lymphomatoid papulosis after a 9‐year follow up: A case report

Lymphomatoid papulosis (LyP) is a self-limiting cutaneous T-cell lymphoproliferative disorder that may progress into malignant lymphoma. Most of the previously reported associated lymphomas are primary cutaneous anaplastic large-cell lymphoma and mycosis fungoides with a low mortality rate. We report a case of primary cutaneous peripheral T-cell lymphoma, not otherwise specified (pcPTCL-NOS), associated with LyP after long-term follow up. The patient was a 79-year old Japanese man followed up for 9 years. He suddenly developed a 3-cm ulcerated lesion on his forehead, which was diagnosed as an exacerbation of LyP. The lesion regressed after conservative treatment, but the patient soon developed multifocal pcPTCL-NOS. Thereafter, the patient developed pneumonia and cerebral infarction and died within a few months of the onset of malignant lymphoma. Aggressive cutaneous lymphoma may develop in LyP patients. The present case re-emphasizes the need for careful follow up of patients with persistent LyP.