Ultrastructure of fibrous papule of the nose.

Abstract

ABSTRACTThree cases of fibrous papule of the nose (FPN) were studied by electron microscopy. All three showed similar ultrastructural features; in the overlying epidermis, a number of large and small vacuoles without limiting membranes were observed within the keratinocytes, and melanocytes and melanosome‐complexes in the keratinocytes were increased in number; in the dermis, a number of mono‐ and binuclear mesenchymal cells which may well be regarded as fibrohistiocytic cells, proliferation and dilation of capillaries and venules, and a considerable number of Zebra bodies were seen. Neither melanocytes nor nevus cells were found in the dermis. These findings suggest that the large pale cells seen in the epidermis by light microscopy are vacuolated keratinocytes and that FPN has characteristics not of a nevocellular nevus but of an angiofibromatous tumor similar to so‐called adenoma sebaceum of Pringle's disease.