The clinical and histological features of 16 patients with a primary cutaneous immunocytoma and 10 patients with a secondary cutaneous immunocytoma are reported. In all cases the diagnosis was based on the presence of monotypic plasma cells or lymphoplasmacytoid cells. Our data show that primary cutaneous immunocytomas are a distinct type of cutaneous lymphoma, characterized by (a) the presence of solitary or localized skin lesions (13 of 16 cases); (b) preferential localization on arms and legs (15 of 16 cases); (c) excellent response to local treatment (15 of 16 cases) and (d) a favourable prognosis. Histologically, these primary cutaneous immunocytomas are characterized by the presence of nodular or diffuse infiltrates with monotypic lymphoplasmacytoid/plasma cells located at the periphery of the infiltrates. Important clinical and histological differences were noted between primary and secondary immunocytomas. In the latter group more widespread skin disease was seen, often in the presence of paraproteins and/or autoimmune diseases. In contrast with the peripheral localization of the monotypic cells in primary cutaneous immunocytomas the monotypic lymphoplasmacytoid/plasma cells in secondary immunocytomas formed diffuse infiltrates or these cells were found dispersed throughout the infiltrate. There were no differences in clinical presentation or course between the different subtypes of cutaneous immunocytomas (lymphoplasmacytic, lymphoplasmacytoid and polymorphic immunocytomas). The differential diagnosis between primary cutaneous immunocytomas and cutaneous plasmacytomas, primary follicular centre cell lymphomas and cutaneous 'pseudolymphomas' is discussed.

Both RT and CHOP PCT are highly effective modes of treatment for PCFCCL. In localized PCFCCL, RT is the treatment of choice. In patients with multiple tumors involving anatomic nonrelated parts of the skin, CHOP rather than COP PCT is the preferred mode of treatment. PCFCCL on the lower legs, a subgroup that characteristically occur in elderly patients, have a higher relapse rate and a less favorable prognosis than PCFCCL presenting on the head or trunk.

The histologic features of 20 patients with cutaneous pseudo‐T‐cell lymphomas other than actinic reticuloid and lymphomatoid papulosis were investigated. Two histologic types of cutaneous pseudo‐T‐cell lymphomas were designated. The band‐like (MF‐like) pattern that simulated mycosis fungoides (MF) and a nodular pattern that mimicked cutaneous T‐cell lymphomas (CTCL) other than MF. Both patterns showed histologic features that generally are not found in CTCL and thus may be helpful in the differential diagnosis from CTCL. However, at present the differential diagnosis between pseudo‐T‐cell lymphomas and CTCL should be based on a combination of clinical and histologic data.

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The authors report the clinical and histologic features of 22 cases of lymphadenosis benigna cutis (LBC) and 35 cases of primary cutaneous follicular center cell (FCC) lymphoma. The differential diagnostic accuracy of criteria generally used for differentiating between benign and malignant cutaneous lymphoid infiltrates was evaluated. The clinical and histologic findings in these two groups showed many similarities. Except for a characteristic clinical presentation of patients with a primary cutaneous FCC lymphoma on the trunk, there was no single clinical or histologic criterion that reliably differentiated between both conditions in all cases. Follow-up data showed that only a small number of patients of the malignant group developed (four of 35 cases) or died of (two of 35 cases) systemic lymphoma. The favorable prognosis of this type of cutaneous lymphoma implies that lack of systemic lymphoma after a five-year follow-up cannot be used as a diagnostic criterion in retrospective studies.