[An atypical presentation of primary cutaneous diffuse B-cell lymphoma, leg type]

Primary cutaneous diffuse B-cell lymphoma, leg type, are rare and aggressive tumours frequently affecting elderly patients. We present a case of a 53-year-old woman with an atypical presentation of primary cutaneous diffuse B-cell lymphoma, leg type.

Eight years after complete excision of a Jessner-Kanof lymphocytic infiltration on the right shoulder, the patient developed a primary cutaneous diffuse B-cell lymphoma, leg type at the same site. The isolated lesion was treated using local radiotherapy. One year later, the patient presented headache associated with a temporal lesion, and biopsy confirmed a relapse. Cerebral CT scan showed an osteolytic temporal lesion while the other investigations revealed no extracutaneous extension. She was treated with R-CHOP chemotherapy and intrathecal methotrexate due to the osteolytic lesion.

The particularity of this case consists in the age of this woman, who was younger than the average, the two atypical localizations on the shoulder, then the temple, and osteolysis, which is not the most frequent extension. Furthermore, to our knowledge, transformation of a Jessner-Kanof lesion into local aggressive primary cutaneous diffuse B-cell lymphoma, leg type, has not been yet described.