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

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.