Primary cutaneous marginal zone lymphoma

PCMZL; primary cutaneous MALT lymphoma (deprecated); cutaneous immunocytoma

PCMZL is an indolent extranodal marginal zone B-cell lymphoma confined to the skin, the second commonest primary cutaneous B-cell lymphoma. It presents with red, violaceous or skin-coloured papules, plaques or nodules on the trunk or upper extremities, often multifocal. Histology shows a mixture of small B cells, lymphoplasmacytoid cells and reactive germinal centres with light-chain restriction. Borrelia burgdorferi has been implicated in a subset of European cases. Although cutaneous recurrence is common (~50%), transformation is rare and 5-year disease-specific survival exceeds 98%.

CurrentLast reviewed 15 May 2026

Clinical features

Solitary or multifocal red-violaceous papules, plaques or small nodules.
Preferential sites — trunk and upper extremities (in contrast to PCFCL which favours head and neck).
Median age 50–60; slight male predominance.
Lesions evolve slowly; ulceration unusual.

Histology and immunophenotype

Nodular dermal infiltrate of small B cells (marginal-zone cells), lymphoplasmacytoid cells, plasma cells and reactive germinal centres; Grenz zone preserved.
Immunophenotype — CD20+, CD79a+, BCL2+, BCL6-, CD10-; plasma-cell component shows κ or λ light-chain restriction.
IgH clonality detectable.
IgG4-related variant recognised; IgH/MALT1 translocations are rare in cutaneous MZL (unlike gastric MALT lymphoma).

Borrelia association

Borrelia burgdorferi DNA detectable in a minority of European PCMZL cases — clearer association in central/eastern Europe than in the UK.
Borrelia serology and PCR considered in patients with relevant exposure or atypical features.
Borrelia-positive PCMZL has responded to doxycycline 100 mg twice daily for 3–4 weeks.

Staging and workup

ISCL-EORTC TNM staging for cutaneous lymphomas.
Baseline — full skin and nodal examination, FBC, LDH, β2-microglobulin, hepatitis serology, CT NCAP to exclude systemic MALT lymphoma, bone-marrow biopsy in selected cases.
Borrelia serology / PCR in cases with relevant exposure.

Management

Asymptomatic or limited disease — observation often appropriate.
Localised disease — localised radiotherapy 24–30 Gy in 12–15 fractions OR surgical excision.
Multifocal disease — intralesional or systemic rituximab; intralesional steroids in selected lesions.
Borrelia-positive cases — doxycycline 100 mg BD × 3–4 weeks first-line.
Chemoimmunotherapy is rarely required.

Prognosis and follow-up

5-year disease-specific survival > 98% — excellent.
Cutaneous recurrence in ~ 50% but does not adversely affect survival.
Transformation to high-grade lymphoma is rare.
Follow-up — annual skin examination, bloods; imaging only if clinical concern.

References

Senff NJ et al. EORTC/ISCL recommendations for cutaneous B-cell lymphomas. Blood; 2008;112:1600–9.

Willemze R et al. WHO-EORTC classification update. Blood; 2019;133:1703–14.

Gilson D et al. British Association of Dermatologists and U.K. Cutaneous Lymphoma Group guidelines for the management of primary cutaneous lymphomas 2018. Br J Dermatol; 2019;180:496–526.