Nonepidermotropic cutaneous lymphomas. A histopathological and immunohistological study of 52 cases.

ABSTRACT

We report the detailed histological and immunohistological findings in 52 cases of nonepidermotropic cutaneous lymphoma, as revealed by cutaneous lesions. The patients presented mainly with cutaneous nodules and, more rarely, with infiltrated plaques, annular erythema, or erythroderma. The staging procedure following the diagnosis revealed lymph node and/or bone marrow involvement in half of the cases. Nearly 60% of the nonepidermotropic cutaneous lymphomas were of the large-cell type. The reticular dermis was involved in all of the cases, and the papillary dermis was involved in only 11 of them. Nonepidermotropic cutaneous lymphomas were of the B-cell, T-cell, and non-B-, non-T-cell type in 38, 13, and 1 case(s), respectively. A monotypic immunoglobulin light chain expression was detected in 33 of 35 tested cases of the B-cell lymphomas, and a loss of one or several pan-T-cell antigens was observed in all of the cases of the T-cell lymphomas. In seven cases (13%), the diagnosis of malignancy was based only on these immunohistological criteria. This study shows that nonepidermotropic cutaneous lymphomas are B-cell lymphomas in 75% of the cases, most often of the large-cell type. It also emphasizes the value of immunohistochemistry to firmly establish malignancy when routine light microscopical findings are questionable.