Primary cerebral diffuse large B-cell lymphoma relapsed solely in the skin with the same clonal origin

Area of Science:

• Oncology
• Neurology
• Dermatology

Background:

• Diffuse large B-cell lymphoma is the most common primary central nervous system lymphoma (PCNSL), often associated with a poor prognosis.
• Relapses typically occur early and within the central nervous system; isolated systemic relapse, particularly in the skin, is exceptionally rare.

Observation:

• An 82-year-old male patient presented with a unique case of PCNSL.
• The patient experienced two consecutive relapses exclusively in the skin, with no concurrent local failure or other systemic involvement.
• Histological and immunophenotypic analysis of all specimens revealed identical lymphoma cells (CD20+, IgM+, bcl-2+, bcl-6+, MUM1+).

Findings:

• B-cell clonality studies confirmed that the brain and subsequent skin tumors originated from the same clone.
• This represents the first documented case of PCNSL relapsing solely in the skin with confirmed clonal identity.

Implications:

• This case expands the known spectrum of PCNSL relapse patterns.
• Highlights the importance of considering cutaneous involvement in PCNSL follow-up, even in the absence of other systemic disease.
• Further research into the mechanisms driving isolated skin relapse in PCNSL may be warranted.