Primary cutaneous marginal zone B-cell lymphoma with anetoderma: spontaneous involution plus de novo clonal expansion

Recurrent primary cutaneous marginal zone lymphoma: a comparative study of initial tumours, recurrences, and outcomes in 61 patients

AIMS

Primary cutaneous marginal zone lymphoma (PCMZL) is considered a lymphoproliferative disorder (International Consensus Classification, ICC) or an overt lymphoma (WHO-HAEM5). Seeking evidence for a reactive process or true lymphoma, we retrieved recurrent PCMZLs from the French Study Group of Cutaneous Lymphoma (GFELC) database.

METHODS

Histology, phenotype (light-chain restriction, immunoglobulin, and immune-receptor translocation-associated protein-1 [IRTA1] expression) and B-cell clonality at diagnosis and recurrence were compared according to recurrence site (local, locoregional, or distant) and outcomes.

RESULTS

Initial lesions of the 61 patients (mean age 52) were mostly isolated on the trunk (48%) and classified T1 (70%). Times to first recurrence for local, locoregional, and distant recurrences, were 20, 29, and 37 months, respectively. Light-chain restriction type did not differ significantly between local/locoregional recurrences and distal recurrences (P = 0.06; n = 60). The same B-cell clones were identified for 23/42 local/locoregional recurrences, while 5/19 distant recurrences showed different clonal profiles (P = 0.0003). No tumour expressed IRTA1. Fifty-eight tumours were heavy-chain (IgG/IgG4) class-switched PCMZLs and 3 IgM+/IgD- PCMZLs. All IgM+ tumours underwent either transformation (skin or brain) into diffuse large B-cell lymphomas (DLBCLs) and extracutaneous spreading.

CONCLUSION

As suggested by WHO-HAEM5, immunoglobulin phenotype assessment (IgM alongside IgD) appears to be a possible valuable tool in the initial diagnosis of PCMZL to differentiate between the indolent class-switched PCMZL (IgM-negative) and IgM+ (IgD-) PCMZL, which has an uncertain prognosis. The variation in B-cell rearrangements and light chain restriction observed in distant recurrences of PCMZL may suggest different antigen-driven stimulation processes.

Cutaneous marginal zone lymphomas

Primary cutaneous marginal zone lymphoma (CMZL) is one of the major primary B-cell lymphomas of skin. Two types are recognized: a more common class-chain switched CMZL, and a much less common IgM+ CMZL. The extremely indolent course, together with other features distinct from most other MALT lymphomas, has led some to question whether at least the class-switched cases should be considered an overt lymphoma.

Cutaneous primary B-cell lymphomas: from diagnosis to treatment

Primary cutaneous B-cell lymphomas are a heterogeneous group of mature B-cells neoplasms with tropism for the skin, whose biology and clinical course differ significantly from the equivalent nodal lymphomas. The most indolent forms comprise the primary cutaneous marginal zone and follicle center B-cell lymphomas that despite the excellent prognosis have cutaneous recurrences very commonly. The most aggressive forms include the primary cutaneous large B-cell lymphomas, consisting in two major groups: the leg type, with poor prognosis, and others, the latter representing a heterogeneous group of lymphomas from which specific entities are supposed to be individualized over time, such as intravascular large B-cell lymphomas. Treatment may include surgical excision, radiotherapy, antibiotics, corticosteroids, interferon, monoclonal antibodies and chemotherapy, depending on the type of lymphoma and on the type and location of the skin lesions. In subtypes with good prognosis is contraindicated overtreatment and in those associated with a worse prognosis the recommended therapy relies on CHOP-like regimens associated with rituximab, assisted or not with local radiotherapy. We review the primary cutaneous B-cell lymphomas, remembering the diagnostic criteria, differential diagnosis, classification, and prognostic factors and presenting the available therapies.