Follicular Mucinosis: A Detailed Morphologic and Immunopathologic Study

Two patients with benign follicular mucinosis (FM) were studied using light and electron microscopy, direct immunofluorescence, and immunoperoxidase cell marker techniques. Light microscopy showed degenerative changes in the follicular outer root sheath and sebaceous gland epithelium, with benign inflammatory cells. Electron microscopy revealed close associations between disattached keratinocytes, macrophages, and Langerhans cells. Direct immunofluorescence highlighted complement (C3) and fibrinogen/fibrin in degenerated areas. Immunoperoxidase studies indicated an increase in T cells, macrophages, and Langerhans cells in the affected follicular epithelium, suggesting a role for cell-mediated immune mechanisms in the disease's pathogenesis.