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4 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
Primary cutaneous marginal zone lymphoma is a very slow-growing lymphoma that appears as pink or purple lumps in the skin, usually on the arms or trunk, and almost never spreads inside the body. WHO-HAEM5 now calls it a lymphoproliferative disorder because it behaves so well; surgery or radiotherapy clears most lesions, and relapses in the skin are common but harmless.
WHO-HAEM5 renamed this entity primary cutaneous marginal zone lymphoproliferative disorder to reflect its indolent behaviour, keeping it beside the other marginal zone lymphomas; it was once called immunocytoma because of its plasmacytic differentiation (Alaggio 2022). In 137 patients, 51 percent had a solitary lesion, 29 percent regional and 20 percent generalised skin disease; surgical excision, local radiotherapy or both were the initial treatment in 86 percent, complete remission followed in 88 percent (93 percent of solitary or localised and 71 percent of multifocal cases), and cutaneous relapses occurred in 44 percent without loss of survival (J Am Acad Dermatol 2013). Unlike other marginal zone lymphomas, 39 percent of primary cutaneous cases with plasmacytic differentiation express IgG4, the highest rate in any B-cell lymphoma, against 1 of 120 non-cutaneous cases (Modern Pathology 2013).
How it differs from its parent: it is confined to the skin at diagnosis, is treated by dermatologists with excision or radiotherapy rather than systemic therapy, and its relapses are skin-only; extracutaneous spread is the exception. Borrelia infection has been implicated in some European cases.
| Setting | Approach | Guideline |
|---|---|---|
| Solitary or localised | Excision or low-dose radiotherapy. | not mapped |
| Multifocal | Observation, intralesional steroids or rituximab; systemic therapy only for extracutaneous spread. | not mapped |