Clinical and Histopathological Characteristics of Cutaneous Lymphoid Hyperplasia: A Comparative Study According to Causative Factors.

Cutaneous lymphoid hyperplasia (CLH) is a heterogeneous type of reactive lymphocytic infiltration resembling cutaneous lymphoma clinically and histopathologically. Few studies describe the relationship between the causative agents and histopathological and immunohistochemical characteristics of CLH. We investigated the clinical and histopathological characteristics of 50 patients with cutaneous CLH and analyzed them according to causative factors and predominant cell types (B or T cells). We retrospectively reviewed medical records to identify causative agents, and histopathological and immunohistochemical features. The majority of infiltrating lymphocytes were T cells (60%). T cell-dominant CLH showed papuloplaque lesions, whereas B cell-dominant CLH lesions were nodular. The infiltration pattern differed between T and B cells. In terms of prognosis, B-cell-predominant lesions tended to respond better to treatment than T-cell-predominant lesions. Hair dyes tended to be associated with multiple CLH lesions in older patients. CLH lesions associated with drugs were located on the head and neck. Insect bites were likely to cause a solitary papular lesion. Histopathologically, infiltration depth was located more superficially than other causes and featured intense eosinophilic infiltration. Thus, our study demonstrated that CLH presents different clinicopathological features according to causative agents and predominant lymphocytic types.