Cutaneous lymphoid hyperplasia presenting as a solitary facial nodule: clinical, histopathological, immunophenotypical, and molecular studies

Abstract

Objective: To elucidate the clinicopathological, immunophenotypical, and molecular characteristics of cutaneous lymphoid hyperplasia presenting as a solitary facial nodule.

Design: Retrospective study.

Setting: University dermatology department.

Patients: Three patients with a solitary facial nodule were studied clinically, histologically, immunophenotypically, and molecularly for T-cell receptor and immunoglobulin heavy chain gene rearrangements.

Main outcome measures: Histological, immunophenotypical, and molecular characteristics in relation to the clinical outcome.

Results: Histologically, dense diffuse lymphocytic infiltrates were present throughout the dermis, occasionally extending into the subcutaneous fat and the epidermis and hair follicles. Small lymphocytes predominated, but in 2 cases there were also medium to large atypical lymphocytes, with some blastlike lymphocytes. The lymphocytic population was mixed with more CD3(+) T cells than CD20(+) B cells, without germinal centers. There were more CD4(+) than CD8(+) cells, and some of the T cells stained for the memory T-cell marker CD45RO. Numerous CD68(+) histiocytes were scattered or formed small aggregates, and in 1 case small granulomas and many scattered S100 protein-positive and CD1a(+)dendritic cells were present. In addition, several polytypic plasma cells, eosinophils, and extravasated erythrocytes were found. Immunostaining for CD10, CD21, CD30, CD56, and BCL6 was negative. The Ki-67 proliferation index was relatively low (5%-10%). Results of the T-cell receptor gene rearrangement studies were positive in 2 cases, 1 of which also harbored clonal B cells. Serologic test results for Borrelia burgdorferi, Borrelia afzelii, and Borrelia garinii were negative in all 3 cases. Two lesions regressed spontaneously after an incisional biopsy, and none of the cases showed recurrence or extracutaneous spread during a follow-up period of 5.0 to 5.5 years.

Conclusions: Cutaneous lymphoid hyperplasia that presents as a solitary facial nodule may share clinical, cytological, immunophenotypical, and molecular features with both benign reactive lymphocytic infiltrates and cutaneous lymphomas, and therefore a careful clinical and therapeutic approach is warranted.