Haematoxylin-eosin鈥搒tained sections demonstrated a moderately dense infiltrate of lymphohistiocytic cells extending from the papillary to the midreticular dermis. Immunocytochemical staining of the lymphocytic infiltrate revealed a predominance of T cells, but some B cells were also identified. Many of the cells stained with the histiocytic markers Mac-387 and CD68. Staining was negative for S100 protein.
On electron microscopy, a population of histiocytes was identified, but no Birbeck granules (specific for Langerhans cells) were present. Dense bodies and comma-shaped bodies were identified in some of the cells.