Primary cutaneous lymphomas (PCL) and skin involvement occur as part of generalized lymphomas originating from other parts than the skin. PCL is defined as lymphomas assumed to arise in skin and which primarily manifest only in skin.
Of PCL arising from T cells (ca. 70 % off PCL), mycosis fungoides dominates followed by cutaneous large cell anaplastic CD30+ T-cell lymphoma, lymphomatoid papulous and peripheral T cell lymphomas. Treatment of PCL arising from T cells is summarized elsewhere. Of PCL arising from B cells (ca. 30 % of PCL), marginal zone lymphomas and DLBCL are the most common. The histological profile correlates poorer with the clinical profile than for other lymphomas. Large cell anaplastic T cell lymphoma and subgroups of DLBCL isolated in skin have relatively good prognosis. The skin area of the primary localization is significant for the prognosis since DLBCL, leg type, has a poorer prognosis tham PCL of type DLBCL.
- For MF, radiation therapy is often part of multiple local measures. Depending on the size of the area and danger of delayed cosmetic disfiguring in the skin, fractionation in 2 Gy x 15 or 3 Gy x 8 is often chosen. Internationally, fractionation down to 2 Gy x 4 is also recommended for single lesions. For generalized disease in the skin that is not treatable by other local measures, total skin electron irradiation is an option.
- CD30+ ALCL is often localized to one or more areas in the skin, and is often suitable for local radiation therapy as 30–40 Gy in fractions of 2 Gy, as recommended in the literature. With more extensive skin involvement, the disease is considered generalized (stage IV) and treated with chemotherapy. Radiation therapy is given to any residual lesions as 2 Gy x 20.
- CD30- ALCL and PTL have -even with primary involvement in skin- a poorer prognosis and are treated with chemotherapy such as aggressive T cell lymphomas, followed sometimes by radiation therapy. For localized involvement (stage PeI), 3 CHOP-based cycles are given followed by radiation therapy as 2 Gy x 20, or only radiation therapy alone. With more advanced skin involvement, the disease is considered generalized (stage IV), and is treated with 6–8 courses and radiation therapy is given to any residual lesions as 2 Gy x 20.
- Indolent PCL of B celle origin (marginal zone lymphoma, folicular lymphoma) with localized disease (stage PeI) or few areas of involvement in skin is treated radiation therapy alone as 2 Gy x 15. For advanced disease in skin (stage IV), treatment can be postponed or possibly given to symptomatic or cosmetically disfigured areas. Systemic treatment is used only if local treatment does not provide adequate control of symptoms.
- For aggressive PCL of B cell origin (DLBCL), radiation therapy is given at the end of chemotherapy according to the stage-adapted arrangement. With local involvement (stage PeI), 3 CHOP-based cycles are given along with radiation therapy as 2 Gy x 20. For extensive skin involvement (stage IV) 6-8 cycles is given, possibly followed by radiation therapy to remaining residual lesions.