Non-Hodgkin lymphoma of the skin excluding mycosis fungoides and cutaneous involvement of adult T-cell leukemia/lymphoma.

Forty-nine cases of cutaneous malignant lymphoma were reviewed in order to analyze the clinicopathological features of these neoplasms. Excluding 13 cases of mycosis fungoides and 4 cases of cutaneous involvement of proven adult T-cell lymphoma/leukemia, the remaining 32 cases were further classified according to their pathological and clinical features. There were 12 primary cutaneous lymphomas, 15 cases of secondary cutaneous involvement of systemic lymphoma, and 5 cases of concurrent skin and lymph node involvement. Histologically, large cell lymphoma predominated in both primary and secondary cutaneous lymphomas. Immunohistochemical study using monoclonal antibodies reactive with B- and T-cells in paraffin sections revealed the cellular lineage in 30 cases. Nineteen cases were of T-cell origin and 11 cases were of B-cell derivation. The prognosis of these patients was rather poor; 25 patients died within 5 years. The predominance of T-cell lymphoma contrasts with a higher frequency of cutaneous B-cell lymphoma in Western countries. As the clinicopathological features of cutaneous lymphomas are diverse, it is suggested that cutaneous lymphomas should be classified and studied in a similar way to their nodal counterparts.